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| |
| <h4 class="subsection">3.17.34 IBM RS/6000 and PowerPC Options</h4> |
| |
| <p><a name="index-RS_002f6000-and-PowerPC-Options-1908"></a><a name="index-IBM-RS_002f6000-and-PowerPC-Options-1909"></a> |
| These ‘<samp><span class="samp">-m</span></samp>’ options are defined for the IBM RS/6000 and PowerPC: |
| <dl> |
| <dt><code>-mpowerpc-gpopt</code><dt><code>-mno-powerpc-gpopt</code><dt><code>-mpowerpc-gfxopt</code><dt><code>-mno-powerpc-gfxopt</code><dt><code>-mpowerpc64</code><dt><code>-mno-powerpc64</code><dt><code>-mmfcrf</code><dt><code>-mno-mfcrf</code><dt><code>-mpopcntb</code><dt><code>-mno-popcntb</code><dt><code>-mpopcntd</code><dt><code>-mno-popcntd</code><dt><code>-mfprnd</code><dt><code>-mno-fprnd</code><dt><code>-mcmpb</code><dt><code>-mno-cmpb</code><dt><code>-mmfpgpr</code><dt><code>-mno-mfpgpr</code><dt><code>-mhard-dfp</code><dt><code>-mno-hard-dfp</code><dd><a name="index-mpowerpc_002dgpopt-1910"></a><a name="index-mno_002dpowerpc_002dgpopt-1911"></a><a name="index-mpowerpc_002dgfxopt-1912"></a><a name="index-mno_002dpowerpc_002dgfxopt-1913"></a><a name="index-mpowerpc64-1914"></a><a name="index-mno_002dpowerpc64-1915"></a><a name="index-mmfcrf-1916"></a><a name="index-mno_002dmfcrf-1917"></a><a name="index-mpopcntb-1918"></a><a name="index-mno_002dpopcntb-1919"></a><a name="index-mpopcntd-1920"></a><a name="index-mno_002dpopcntd-1921"></a><a name="index-mfprnd-1922"></a><a name="index-mno_002dfprnd-1923"></a><a name="index-mcmpb-1924"></a><a name="index-mno_002dcmpb-1925"></a><a name="index-mmfpgpr-1926"></a><a name="index-mno_002dmfpgpr-1927"></a><a name="index-mhard_002ddfp-1928"></a><a name="index-mno_002dhard_002ddfp-1929"></a>You use these options to specify which instructions are available on the |
| processor you are using. The default value of these options is |
| determined when configuring GCC. Specifying the |
| <samp><span class="option">-mcpu=</span><var>cpu_type</var></samp> overrides the specification of these |
| options. We recommend you use the <samp><span class="option">-mcpu=</span><var>cpu_type</var></samp> option |
| rather than the options listed above. |
| |
| <p>Specifying <samp><span class="option">-mpowerpc-gpopt</span></samp> allows |
| GCC to use the optional PowerPC architecture instructions in the |
| General Purpose group, including floating-point square root. Specifying |
| <samp><span class="option">-mpowerpc-gfxopt</span></samp> allows GCC to |
| use the optional PowerPC architecture instructions in the Graphics |
| group, including floating-point select. |
| |
| <p>The <samp><span class="option">-mmfcrf</span></samp> option allows GCC to generate the move from |
| condition register field instruction implemented on the POWER4 |
| processor and other processors that support the PowerPC V2.01 |
| architecture. |
| The <samp><span class="option">-mpopcntb</span></samp> option allows GCC to generate the popcount and |
| double-precision FP reciprocal estimate instruction implemented on the |
| POWER5 processor and other processors that support the PowerPC V2.02 |
| architecture. |
| The <samp><span class="option">-mpopcntd</span></samp> option allows GCC to generate the popcount |
| instruction implemented on the POWER7 processor and other processors |
| that support the PowerPC V2.06 architecture. |
| The <samp><span class="option">-mfprnd</span></samp> option allows GCC to generate the FP round to |
| integer instructions implemented on the POWER5+ processor and other |
| processors that support the PowerPC V2.03 architecture. |
| The <samp><span class="option">-mcmpb</span></samp> option allows GCC to generate the compare bytes |
| instruction implemented on the POWER6 processor and other processors |
| that support the PowerPC V2.05 architecture. |
| The <samp><span class="option">-mmfpgpr</span></samp> option allows GCC to generate the FP move to/from |
| general-purpose register instructions implemented on the POWER6X |
| processor and other processors that support the extended PowerPC V2.05 |
| architecture. |
| The <samp><span class="option">-mhard-dfp</span></samp> option allows GCC to generate the decimal |
| floating-point instructions implemented on some POWER processors. |
| |
| <p>The <samp><span class="option">-mpowerpc64</span></samp> option allows GCC to generate the additional |
| 64-bit instructions that are found in the full PowerPC64 architecture |
| and to treat GPRs as 64-bit, doubleword quantities. GCC defaults to |
| <samp><span class="option">-mno-powerpc64</span></samp>. |
| |
| <br><dt><code>-mcpu=</code><var>cpu_type</var><dd><a name="index-mcpu-1930"></a>Set architecture type, register usage, and |
| instruction scheduling parameters for machine type <var>cpu_type</var>. |
| Supported values for <var>cpu_type</var> are ‘<samp><span class="samp">401</span></samp>’, ‘<samp><span class="samp">403</span></samp>’, |
| ‘<samp><span class="samp">405</span></samp>’, ‘<samp><span class="samp">405fp</span></samp>’, ‘<samp><span class="samp">440</span></samp>’, ‘<samp><span class="samp">440fp</span></samp>’, ‘<samp><span class="samp">464</span></samp>’, ‘<samp><span class="samp">464fp</span></samp>’, |
| ‘<samp><span class="samp">476</span></samp>’, ‘<samp><span class="samp">476fp</span></samp>’, ‘<samp><span class="samp">505</span></samp>’, ‘<samp><span class="samp">601</span></samp>’, ‘<samp><span class="samp">602</span></samp>’, ‘<samp><span class="samp">603</span></samp>’, |
| ‘<samp><span class="samp">603e</span></samp>’, ‘<samp><span class="samp">604</span></samp>’, ‘<samp><span class="samp">604e</span></samp>’, ‘<samp><span class="samp">620</span></samp>’, ‘<samp><span class="samp">630</span></samp>’, ‘<samp><span class="samp">740</span></samp>’, |
| ‘<samp><span class="samp">7400</span></samp>’, ‘<samp><span class="samp">7450</span></samp>’, ‘<samp><span class="samp">750</span></samp>’, ‘<samp><span class="samp">801</span></samp>’, ‘<samp><span class="samp">821</span></samp>’, ‘<samp><span class="samp">823</span></samp>’, |
| ‘<samp><span class="samp">860</span></samp>’, ‘<samp><span class="samp">970</span></samp>’, ‘<samp><span class="samp">8540</span></samp>’, ‘<samp><span class="samp">a2</span></samp>’, ‘<samp><span class="samp">e300c2</span></samp>’, |
| ‘<samp><span class="samp">e300c3</span></samp>’, ‘<samp><span class="samp">e500mc</span></samp>’, ‘<samp><span class="samp">e500mc64</span></samp>’, ‘<samp><span class="samp">e5500</span></samp>’, |
| ‘<samp><span class="samp">e6500</span></samp>’, ‘<samp><span class="samp">ec603e</span></samp>’, ‘<samp><span class="samp">G3</span></samp>’, ‘<samp><span class="samp">G4</span></samp>’, ‘<samp><span class="samp">G5</span></samp>’, |
| ‘<samp><span class="samp">titan</span></samp>’, ‘<samp><span class="samp">power3</span></samp>’, ‘<samp><span class="samp">power4</span></samp>’, ‘<samp><span class="samp">power5</span></samp>’, ‘<samp><span class="samp">power5+</span></samp>’, |
| ‘<samp><span class="samp">power6</span></samp>’, ‘<samp><span class="samp">power6x</span></samp>’, ‘<samp><span class="samp">power7</span></samp>’, ‘<samp><span class="samp">power8</span></samp>’, ‘<samp><span class="samp">powerpc</span></samp>’, |
| ‘<samp><span class="samp">powerpc64</span></samp>’, and ‘<samp><span class="samp">rs64</span></samp>’. |
| |
| <p><samp><span class="option">-mcpu=powerpc</span></samp>, and <samp><span class="option">-mcpu=powerpc64</span></samp> specify pure 32-bit |
| PowerPC and 64-bit PowerPC architecture machine |
| types, with an appropriate, generic processor model assumed for |
| scheduling purposes. |
| |
| <p>The other options specify a specific processor. Code generated under |
| those options runs best on that processor, and may not run at all on |
| others. |
| |
| <p>The <samp><span class="option">-mcpu</span></samp> options automatically enable or disable the |
| following options: |
| |
| <pre class="smallexample"> -maltivec -mfprnd -mhard-float -mmfcrf -mmultiple |
| -mpopcntb -mpopcntd -mpowerpc64 |
| -mpowerpc-gpopt -mpowerpc-gfxopt -msingle-float -mdouble-float |
| -msimple-fpu -mstring -mmulhw -mdlmzb -mmfpgpr -mvsx |
| </pre> |
| <p>The particular options set for any particular CPU varies between |
| compiler versions, depending on what setting seems to produce optimal |
| code for that CPU; it doesn't necessarily reflect the actual hardware's |
| capabilities. If you wish to set an individual option to a particular |
| value, you may specify it after the <samp><span class="option">-mcpu</span></samp> option, like |
| <samp><span class="option">-mcpu=970 -mno-altivec</span></samp>. |
| |
| <p>On AIX, the <samp><span class="option">-maltivec</span></samp> and <samp><span class="option">-mpowerpc64</span></samp> options are |
| not enabled or disabled by the <samp><span class="option">-mcpu</span></samp> option at present because |
| AIX does not have full support for these options. You may still |
| enable or disable them individually if you're sure it'll work in your |
| environment. |
| |
| <br><dt><code>-mtune=</code><var>cpu_type</var><dd><a name="index-mtune-1931"></a>Set the instruction scheduling parameters for machine type |
| <var>cpu_type</var>, but do not set the architecture type or register usage, |
| as <samp><span class="option">-mcpu=</span><var>cpu_type</var></samp> does. The same |
| values for <var>cpu_type</var> are used for <samp><span class="option">-mtune</span></samp> as for |
| <samp><span class="option">-mcpu</span></samp>. If both are specified, the code generated uses the |
| architecture and registers set by <samp><span class="option">-mcpu</span></samp>, but the |
| scheduling parameters set by <samp><span class="option">-mtune</span></samp>. |
| |
| <br><dt><code>-mcmodel=small</code><dd><a name="index-mcmodel_003dsmall-1932"></a>Generate PowerPC64 code for the small model: The TOC is limited to |
| 64k. |
| |
| <br><dt><code>-mcmodel=medium</code><dd><a name="index-mcmodel_003dmedium-1933"></a>Generate PowerPC64 code for the medium model: The TOC and other static |
| data may be up to a total of 4G in size. |
| |
| <br><dt><code>-mcmodel=large</code><dd><a name="index-mcmodel_003dlarge-1934"></a>Generate PowerPC64 code for the large model: The TOC may be up to 4G |
| in size. Other data and code is only limited by the 64-bit address |
| space. |
| |
| <br><dt><code>-maltivec</code><dt><code>-mno-altivec</code><dd><a name="index-maltivec-1935"></a><a name="index-mno_002daltivec-1936"></a>Generate code that uses (does not use) AltiVec instructions, and also |
| enable the use of built-in functions that allow more direct access to |
| the AltiVec instruction set. You may also need to set |
| <samp><span class="option">-mabi=altivec</span></samp> to adjust the current ABI with AltiVec ABI |
| enhancements. |
| |
| <br><dt><code>-mvrsave</code><dt><code>-mno-vrsave</code><dd><a name="index-mvrsave-1937"></a><a name="index-mno_002dvrsave-1938"></a>Generate VRSAVE instructions when generating AltiVec code. |
| |
| <br><dt><code>-mgen-cell-microcode</code><dd><a name="index-mgen_002dcell_002dmicrocode-1939"></a>Generate Cell microcode instructions. |
| |
| <br><dt><code>-mwarn-cell-microcode</code><dd><a name="index-mwarn_002dcell_002dmicrocode-1940"></a>Warn when a Cell microcode instruction is emitted. An example |
| of a Cell microcode instruction is a variable shift. |
| |
| <br><dt><code>-msecure-plt</code><dd><a name="index-msecure_002dplt-1941"></a>Generate code that allows <samp><span class="command">ld</span></samp> and <samp><span class="command">ld.so</span></samp> |
| to build executables and shared |
| libraries with non-executable <code>.plt</code> and <code>.got</code> sections. |
| This is a PowerPC |
| 32-bit SYSV ABI option. |
| |
| <br><dt><code>-mbss-plt</code><dd><a name="index-mbss_002dplt-1942"></a>Generate code that uses a BSS <code>.plt</code> section that <samp><span class="command">ld.so</span></samp> |
| fills in, and |
| requires <code>.plt</code> and <code>.got</code> |
| sections that are both writable and executable. |
| This is a PowerPC 32-bit SYSV ABI option. |
| |
| <br><dt><code>-misel</code><dt><code>-mno-isel</code><dd><a name="index-misel-1943"></a><a name="index-mno_002disel-1944"></a>This switch enables or disables the generation of ISEL instructions. |
| |
| <br><dt><code>-misel=</code><var>yes/no</var><dd>This switch has been deprecated. Use <samp><span class="option">-misel</span></samp> and |
| <samp><span class="option">-mno-isel</span></samp> instead. |
| |
| <br><dt><code>-mspe</code><dt><code>-mno-spe</code><dd><a name="index-mspe-1945"></a><a name="index-mno_002dspe-1946"></a>This switch enables or disables the generation of SPE simd |
| instructions. |
| |
| <br><dt><code>-mpaired</code><dt><code>-mno-paired</code><dd><a name="index-mpaired-1947"></a><a name="index-mno_002dpaired-1948"></a>This switch enables or disables the generation of PAIRED simd |
| instructions. |
| |
| <br><dt><code>-mspe=</code><var>yes/no</var><dd>This option has been deprecated. Use <samp><span class="option">-mspe</span></samp> and |
| <samp><span class="option">-mno-spe</span></samp> instead. |
| |
| <br><dt><code>-mvsx</code><dt><code>-mno-vsx</code><dd><a name="index-mvsx-1949"></a><a name="index-mno_002dvsx-1950"></a>Generate code that uses (does not use) vector/scalar (VSX) |
| instructions, and also enable the use of built-in functions that allow |
| more direct access to the VSX instruction set. |
| |
| <br><dt><code>-mfloat-gprs=</code><var>yes/single/double/no</var><dt><code>-mfloat-gprs</code><dd><a name="index-mfloat_002dgprs-1951"></a>This switch enables or disables the generation of floating-point |
| operations on the general-purpose registers for architectures that |
| support it. |
| |
| <p>The argument <var>yes</var> or <var>single</var> enables the use of |
| single-precision floating-point operations. |
| |
| <p>The argument <var>double</var> enables the use of single and |
| double-precision floating-point operations. |
| |
| <p>The argument <var>no</var> disables floating-point operations on the |
| general-purpose registers. |
| |
| <p>This option is currently only available on the MPC854x. |
| |
| <br><dt><code>-m32</code><dt><code>-m64</code><dd><a name="index-m32-1952"></a><a name="index-m64-1953"></a>Generate code for 32-bit or 64-bit environments of Darwin and SVR4 |
| targets (including GNU/Linux). The 32-bit environment sets int, long |
| and pointer to 32 bits and generates code that runs on any PowerPC |
| variant. The 64-bit environment sets int to 32 bits and long and |
| pointer to 64 bits, and generates code for PowerPC64, as for |
| <samp><span class="option">-mpowerpc64</span></samp>. |
| |
| <br><dt><code>-mfull-toc</code><dt><code>-mno-fp-in-toc</code><dt><code>-mno-sum-in-toc</code><dt><code>-mminimal-toc</code><dd><a name="index-mfull_002dtoc-1954"></a><a name="index-mno_002dfp_002din_002dtoc-1955"></a><a name="index-mno_002dsum_002din_002dtoc-1956"></a><a name="index-mminimal_002dtoc-1957"></a>Modify generation of the TOC (Table Of Contents), which is created for |
| every executable file. The <samp><span class="option">-mfull-toc</span></samp> option is selected by |
| default. In that case, GCC allocates at least one TOC entry for |
| each unique non-automatic variable reference in your program. GCC |
| also places floating-point constants in the TOC. However, only |
| 16,384 entries are available in the TOC. |
| |
| <p>If you receive a linker error message that saying you have overflowed |
| the available TOC space, you can reduce the amount of TOC space used |
| with the <samp><span class="option">-mno-fp-in-toc</span></samp> and <samp><span class="option">-mno-sum-in-toc</span></samp> options. |
| <samp><span class="option">-mno-fp-in-toc</span></samp> prevents GCC from putting floating-point |
| constants in the TOC and <samp><span class="option">-mno-sum-in-toc</span></samp> forces GCC to |
| generate code to calculate the sum of an address and a constant at |
| run time instead of putting that sum into the TOC. You may specify one |
| or both of these options. Each causes GCC to produce very slightly |
| slower and larger code at the expense of conserving TOC space. |
| |
| <p>If you still run out of space in the TOC even when you specify both of |
| these options, specify <samp><span class="option">-mminimal-toc</span></samp> instead. This option causes |
| GCC to make only one TOC entry for every file. When you specify this |
| option, GCC produces code that is slower and larger but which |
| uses extremely little TOC space. You may wish to use this option |
| only on files that contain less frequently-executed code. |
| |
| <br><dt><code>-maix64</code><dt><code>-maix32</code><dd><a name="index-maix64-1958"></a><a name="index-maix32-1959"></a>Enable 64-bit AIX ABI and calling convention: 64-bit pointers, 64-bit |
| <code>long</code> type, and the infrastructure needed to support them. |
| Specifying <samp><span class="option">-maix64</span></samp> implies <samp><span class="option">-mpowerpc64</span></samp>, |
| while <samp><span class="option">-maix32</span></samp> disables the 64-bit ABI and |
| implies <samp><span class="option">-mno-powerpc64</span></samp>. GCC defaults to <samp><span class="option">-maix32</span></samp>. |
| |
| <br><dt><code>-mxl-compat</code><dt><code>-mno-xl-compat</code><dd><a name="index-mxl_002dcompat-1960"></a><a name="index-mno_002dxl_002dcompat-1961"></a>Produce code that conforms more closely to IBM XL compiler semantics |
| when using AIX-compatible ABI. Pass floating-point arguments to |
| prototyped functions beyond the register save area (RSA) on the stack |
| in addition to argument FPRs. Do not assume that most significant |
| double in 128-bit long double value is properly rounded when comparing |
| values and converting to double. Use XL symbol names for long double |
| support routines. |
| |
| <p>The AIX calling convention was extended but not initially documented to |
| handle an obscure K&R C case of calling a function that takes the |
| address of its arguments with fewer arguments than declared. IBM XL |
| compilers access floating-point arguments that do not fit in the |
| RSA from the stack when a subroutine is compiled without |
| optimization. Because always storing floating-point arguments on the |
| stack is inefficient and rarely needed, this option is not enabled by |
| default and only is necessary when calling subroutines compiled by IBM |
| XL compilers without optimization. |
| |
| <br><dt><code>-mpe</code><dd><a name="index-mpe-1962"></a>Support <dfn>IBM RS/6000 SP</dfn> <dfn>Parallel Environment</dfn> (PE). Link an |
| application written to use message passing with special startup code to |
| enable the application to run. The system must have PE installed in the |
| standard location (<samp><span class="file">/usr/lpp/ppe.poe/</span></samp>), or the <samp><span class="file">specs</span></samp> file |
| must be overridden with the <samp><span class="option">-specs=</span></samp> option to specify the |
| appropriate directory location. The Parallel Environment does not |
| support threads, so the <samp><span class="option">-mpe</span></samp> option and the <samp><span class="option">-pthread</span></samp> |
| option are incompatible. |
| |
| <br><dt><code>-malign-natural</code><dt><code>-malign-power</code><dd><a name="index-malign_002dnatural-1963"></a><a name="index-malign_002dpower-1964"></a>On AIX, 32-bit Darwin, and 64-bit PowerPC GNU/Linux, the option |
| <samp><span class="option">-malign-natural</span></samp> overrides the ABI-defined alignment of larger |
| types, such as floating-point doubles, on their natural size-based boundary. |
| The option <samp><span class="option">-malign-power</span></samp> instructs GCC to follow the ABI-specified |
| alignment rules. GCC defaults to the standard alignment defined in the ABI. |
| |
| <p>On 64-bit Darwin, natural alignment is the default, and <samp><span class="option">-malign-power</span></samp> |
| is not supported. |
| |
| <br><dt><code>-msoft-float</code><dt><code>-mhard-float</code><dd><a name="index-msoft_002dfloat-1965"></a><a name="index-mhard_002dfloat-1966"></a>Generate code that does not use (uses) the floating-point register set. |
| Software floating-point emulation is provided if you use the |
| <samp><span class="option">-msoft-float</span></samp> option, and pass the option to GCC when linking. |
| |
| <br><dt><code>-msingle-float</code><dt><code>-mdouble-float</code><dd><a name="index-msingle_002dfloat-1967"></a><a name="index-mdouble_002dfloat-1968"></a>Generate code for single- or double-precision floating-point operations. |
| <samp><span class="option">-mdouble-float</span></samp> implies <samp><span class="option">-msingle-float</span></samp>. |
| |
| <br><dt><code>-msimple-fpu</code><dd><a name="index-msimple_002dfpu-1969"></a>Do not generate <code>sqrt</code> and <code>div</code> instructions for hardware |
| floating-point unit. |
| |
| <br><dt><code>-mfpu=</code><var>name</var><dd><a name="index-mfpu-1970"></a>Specify type of floating-point unit. Valid values for <var>name</var> are |
| ‘<samp><span class="samp">sp_lite</span></samp>’ (equivalent to <samp><span class="option">-msingle-float -msimple-fpu</span></samp>), |
| ‘<samp><span class="samp">dp_lite</span></samp>’ (equivalent to <samp><span class="option">-mdouble-float -msimple-fpu</span></samp>), |
| ‘<samp><span class="samp">sp_full</span></samp>’ (equivalent to <samp><span class="option">-msingle-float</span></samp>), |
| and ‘<samp><span class="samp">dp_full</span></samp>’ (equivalent to <samp><span class="option">-mdouble-float</span></samp>). |
| |
| <br><dt><code>-mxilinx-fpu</code><dd><a name="index-mxilinx_002dfpu-1971"></a>Perform optimizations for the floating-point unit on Xilinx PPC 405/440. |
| |
| <br><dt><code>-mmultiple</code><dt><code>-mno-multiple</code><dd><a name="index-mmultiple-1972"></a><a name="index-mno_002dmultiple-1973"></a>Generate code that uses (does not use) the load multiple word |
| instructions and the store multiple word instructions. These |
| instructions are generated by default on POWER systems, and not |
| generated on PowerPC systems. Do not use <samp><span class="option">-mmultiple</span></samp> on little-endian |
| PowerPC systems, since those instructions do not work when the |
| processor is in little-endian mode. The exceptions are PPC740 and |
| PPC750 which permit these instructions in little-endian mode. |
| |
| <br><dt><code>-mstring</code><dt><code>-mno-string</code><dd><a name="index-mstring-1974"></a><a name="index-mno_002dstring-1975"></a>Generate code that uses (does not use) the load string instructions |
| and the store string word instructions to save multiple registers and |
| do small block moves. These instructions are generated by default on |
| POWER systems, and not generated on PowerPC systems. Do not use |
| <samp><span class="option">-mstring</span></samp> on little-endian PowerPC systems, since those |
| instructions do not work when the processor is in little-endian mode. |
| The exceptions are PPC740 and PPC750 which permit these instructions |
| in little-endian mode. |
| |
| <br><dt><code>-mupdate</code><dt><code>-mno-update</code><dd><a name="index-mupdate-1976"></a><a name="index-mno_002dupdate-1977"></a>Generate code that uses (does not use) the load or store instructions |
| that update the base register to the address of the calculated memory |
| location. These instructions are generated by default. If you use |
| <samp><span class="option">-mno-update</span></samp>, there is a small window between the time that the |
| stack pointer is updated and the address of the previous frame is |
| stored, which means code that walks the stack frame across interrupts or |
| signals may get corrupted data. |
| |
| <br><dt><code>-mavoid-indexed-addresses</code><dt><code>-mno-avoid-indexed-addresses</code><dd><a name="index-mavoid_002dindexed_002daddresses-1978"></a><a name="index-mno_002davoid_002dindexed_002daddresses-1979"></a>Generate code that tries to avoid (not avoid) the use of indexed load |
| or store instructions. These instructions can incur a performance |
| penalty on Power6 processors in certain situations, such as when |
| stepping through large arrays that cross a 16M boundary. This option |
| is enabled by default when targeting Power6 and disabled otherwise. |
| |
| <br><dt><code>-mfused-madd</code><dt><code>-mno-fused-madd</code><dd><a name="index-mfused_002dmadd-1980"></a><a name="index-mno_002dfused_002dmadd-1981"></a>Generate code that uses (does not use) the floating-point multiply and |
| accumulate instructions. These instructions are generated by default |
| if hardware floating point is used. The machine-dependent |
| <samp><span class="option">-mfused-madd</span></samp> option is now mapped to the machine-independent |
| <samp><span class="option">-ffp-contract=fast</span></samp> option, and <samp><span class="option">-mno-fused-madd</span></samp> is |
| mapped to <samp><span class="option">-ffp-contract=off</span></samp>. |
| |
| <br><dt><code>-mmulhw</code><dt><code>-mno-mulhw</code><dd><a name="index-mmulhw-1982"></a><a name="index-mno_002dmulhw-1983"></a>Generate code that uses (does not use) the half-word multiply and |
| multiply-accumulate instructions on the IBM 405, 440, 464 and 476 processors. |
| These instructions are generated by default when targeting those |
| processors. |
| |
| <br><dt><code>-mdlmzb</code><dt><code>-mno-dlmzb</code><dd><a name="index-mdlmzb-1984"></a><a name="index-mno_002ddlmzb-1985"></a>Generate code that uses (does not use) the string-search ‘<samp><span class="samp">dlmzb</span></samp>’ |
| instruction on the IBM 405, 440, 464 and 476 processors. This instruction is |
| generated by default when targeting those processors. |
| |
| <br><dt><code>-mno-bit-align</code><dt><code>-mbit-align</code><dd><a name="index-mno_002dbit_002dalign-1986"></a><a name="index-mbit_002dalign-1987"></a>On System V.4 and embedded PowerPC systems do not (do) force structures |
| and unions that contain bit-fields to be aligned to the base type of the |
| bit-field. |
| |
| <p>For example, by default a structure containing nothing but 8 |
| <code>unsigned</code> bit-fields of length 1 is aligned to a 4-byte |
| boundary and has a size of 4 bytes. By using <samp><span class="option">-mno-bit-align</span></samp>, |
| the structure is aligned to a 1-byte boundary and is 1 byte in |
| size. |
| |
| <br><dt><code>-mno-strict-align</code><dt><code>-mstrict-align</code><dd><a name="index-mno_002dstrict_002dalign-1988"></a><a name="index-mstrict_002dalign-1989"></a>On System V.4 and embedded PowerPC systems do not (do) assume that |
| unaligned memory references are handled by the system. |
| |
| <br><dt><code>-mrelocatable</code><dt><code>-mno-relocatable</code><dd><a name="index-mrelocatable-1990"></a><a name="index-mno_002drelocatable-1991"></a>Generate code that allows (does not allow) a static executable to be |
| relocated to a different address at run time. A simple embedded |
| PowerPC system loader should relocate the entire contents of |
| <code>.got2</code> and 4-byte locations listed in the <code>.fixup</code> section, |
| a table of 32-bit addresses generated by this option. For this to |
| work, all objects linked together must be compiled with |
| <samp><span class="option">-mrelocatable</span></samp> or <samp><span class="option">-mrelocatable-lib</span></samp>. |
| <samp><span class="option">-mrelocatable</span></samp> code aligns the stack to an 8-byte boundary. |
| |
| <br><dt><code>-mrelocatable-lib</code><dt><code>-mno-relocatable-lib</code><dd><a name="index-mrelocatable_002dlib-1992"></a><a name="index-mno_002drelocatable_002dlib-1993"></a>Like <samp><span class="option">-mrelocatable</span></samp>, <samp><span class="option">-mrelocatable-lib</span></samp> generates a |
| <code>.fixup</code> section to allow static executables to be relocated at |
| run time, but <samp><span class="option">-mrelocatable-lib</span></samp> does not use the smaller stack |
| alignment of <samp><span class="option">-mrelocatable</span></samp>. Objects compiled with |
| <samp><span class="option">-mrelocatable-lib</span></samp> may be linked with objects compiled with |
| any combination of the <samp><span class="option">-mrelocatable</span></samp> options. |
| |
| <br><dt><code>-mno-toc</code><dt><code>-mtoc</code><dd><a name="index-mno_002dtoc-1994"></a><a name="index-mtoc-1995"></a>On System V.4 and embedded PowerPC systems do not (do) assume that |
| register 2 contains a pointer to a global area pointing to the addresses |
| used in the program. |
| |
| <br><dt><code>-mlittle</code><dt><code>-mlittle-endian</code><dd><a name="index-mlittle-1996"></a><a name="index-mlittle_002dendian-1997"></a>On System V.4 and embedded PowerPC systems compile code for the |
| processor in little-endian mode. The <samp><span class="option">-mlittle-endian</span></samp> option is |
| the same as <samp><span class="option">-mlittle</span></samp>. |
| |
| <br><dt><code>-mbig</code><dt><code>-mbig-endian</code><dd><a name="index-mbig-1998"></a><a name="index-mbig_002dendian-1999"></a>On System V.4 and embedded PowerPC systems compile code for the |
| processor in big-endian mode. The <samp><span class="option">-mbig-endian</span></samp> option is |
| the same as <samp><span class="option">-mbig</span></samp>. |
| |
| <br><dt><code>-mdynamic-no-pic</code><dd><a name="index-mdynamic_002dno_002dpic-2000"></a>On Darwin and Mac OS X systems, compile code so that it is not |
| relocatable, but that its external references are relocatable. The |
| resulting code is suitable for applications, but not shared |
| libraries. |
| |
| <br><dt><code>-msingle-pic-base</code><dd><a name="index-msingle_002dpic_002dbase-2001"></a>Treat the register used for PIC addressing as read-only, rather than |
| loading it in the prologue for each function. The runtime system is |
| responsible for initializing this register with an appropriate value |
| before execution begins. |
| |
| <br><dt><code>-mprioritize-restricted-insns=</code><var>priority</var><dd><a name="index-mprioritize_002drestricted_002dinsns-2002"></a>This option controls the priority that is assigned to |
| dispatch-slot restricted instructions during the second scheduling |
| pass. The argument <var>priority</var> takes the value ‘<samp><span class="samp">0</span></samp>’, ‘<samp><span class="samp">1</span></samp>’, |
| or ‘<samp><span class="samp">2</span></samp>’ to assign no, highest, or second-highest (respectively) |
| priority to dispatch-slot restricted |
| instructions. |
| |
| <br><dt><code>-msched-costly-dep=</code><var>dependence_type</var><dd><a name="index-msched_002dcostly_002ddep-2003"></a>This option controls which dependences are considered costly |
| by the target during instruction scheduling. The argument |
| <var>dependence_type</var> takes one of the following values: |
| |
| <dl> |
| <dt>‘<samp><span class="samp">no</span></samp>’<dd>No dependence is costly. |
| |
| <br><dt>‘<samp><span class="samp">all</span></samp>’<dd>All dependences are costly. |
| |
| <br><dt>‘<samp><span class="samp">true_store_to_load</span></samp>’<dd>A true dependence from store to load is costly. |
| |
| <br><dt>‘<samp><span class="samp">store_to_load</span></samp>’<dd>Any dependence from store to load is costly. |
| |
| <br><dt><var>number</var><dd>Any dependence for which the latency is greater than or equal to |
| <var>number</var> is costly. |
| </dl> |
| |
| <br><dt><code>-minsert-sched-nops=</code><var>scheme</var><dd><a name="index-minsert_002dsched_002dnops-2004"></a>This option controls which NOP insertion scheme is used during |
| the second scheduling pass. The argument <var>scheme</var> takes one of the |
| following values: |
| |
| <dl> |
| <dt>‘<samp><span class="samp">no</span></samp>’<dd>Don't insert NOPs. |
| |
| <br><dt>‘<samp><span class="samp">pad</span></samp>’<dd>Pad with NOPs any dispatch group that has vacant issue slots, |
| according to the scheduler's grouping. |
| |
| <br><dt>‘<samp><span class="samp">regroup_exact</span></samp>’<dd>Insert NOPs to force costly dependent insns into |
| separate groups. Insert exactly as many NOPs as needed to force an insn |
| to a new group, according to the estimated processor grouping. |
| |
| <br><dt><var>number</var><dd>Insert NOPs to force costly dependent insns into |
| separate groups. Insert <var>number</var> NOPs to force an insn to a new group. |
| </dl> |
| |
| <br><dt><code>-mcall-sysv</code><dd><a name="index-mcall_002dsysv-2005"></a>On System V.4 and embedded PowerPC systems compile code using calling |
| conventions that adhere to the March 1995 draft of the System V |
| Application Binary Interface, PowerPC processor supplement. This is the |
| default unless you configured GCC using ‘<samp><span class="samp">powerpc-*-eabiaix</span></samp>’. |
| |
| <br><dt><code>-mcall-sysv-eabi</code><dt><code>-mcall-eabi</code><dd><a name="index-mcall_002dsysv_002deabi-2006"></a><a name="index-mcall_002deabi-2007"></a>Specify both <samp><span class="option">-mcall-sysv</span></samp> and <samp><span class="option">-meabi</span></samp> options. |
| |
| <br><dt><code>-mcall-sysv-noeabi</code><dd><a name="index-mcall_002dsysv_002dnoeabi-2008"></a>Specify both <samp><span class="option">-mcall-sysv</span></samp> and <samp><span class="option">-mno-eabi</span></samp> options. |
| |
| <br><dt><code>-mcall-aixdesc</code><dd><a name="index-m-2009"></a>On System V.4 and embedded PowerPC systems compile code for the AIX |
| operating system. |
| |
| <br><dt><code>-mcall-linux</code><dd><a name="index-mcall_002dlinux-2010"></a>On System V.4 and embedded PowerPC systems compile code for the |
| Linux-based GNU system. |
| |
| <br><dt><code>-mcall-freebsd</code><dd><a name="index-mcall_002dfreebsd-2011"></a>On System V.4 and embedded PowerPC systems compile code for the |
| FreeBSD operating system. |
| |
| <br><dt><code>-mcall-netbsd</code><dd><a name="index-mcall_002dnetbsd-2012"></a>On System V.4 and embedded PowerPC systems compile code for the |
| NetBSD operating system. |
| |
| <br><dt><code>-mcall-openbsd</code><dd><a name="index-mcall_002dnetbsd-2013"></a>On System V.4 and embedded PowerPC systems compile code for the |
| OpenBSD operating system. |
| |
| <br><dt><code>-maix-struct-return</code><dd><a name="index-maix_002dstruct_002dreturn-2014"></a>Return all structures in memory (as specified by the AIX ABI). |
| |
| <br><dt><code>-msvr4-struct-return</code><dd><a name="index-msvr4_002dstruct_002dreturn-2015"></a>Return structures smaller than 8 bytes in registers (as specified by the |
| SVR4 ABI). |
| |
| <br><dt><code>-mabi=</code><var>abi-type</var><dd><a name="index-mabi-2016"></a>Extend the current ABI with a particular extension, or remove such extension. |
| Valid values are <var>altivec</var>, <var>no-altivec</var>, <var>spe</var>, |
| <var>no-spe</var>, <var>ibmlongdouble</var>, <var>ieeelongdouble</var>. |
| |
| <br><dt><code>-mabi=spe</code><dd><a name="index-mabi_003dspe-2017"></a>Extend the current ABI with SPE ABI extensions. This does not change |
| the default ABI, instead it adds the SPE ABI extensions to the current |
| ABI. |
| |
| <br><dt><code>-mabi=no-spe</code><dd><a name="index-mabi_003dno_002dspe-2018"></a>Disable Book-E SPE ABI extensions for the current ABI. |
| |
| <br><dt><code>-mabi=ibmlongdouble</code><dd><a name="index-mabi_003dibmlongdouble-2019"></a>Change the current ABI to use IBM extended-precision long double. |
| This is a PowerPC 32-bit SYSV ABI option. |
| |
| <br><dt><code>-mabi=ieeelongdouble</code><dd><a name="index-mabi_003dieeelongdouble-2020"></a>Change the current ABI to use IEEE extended-precision long double. |
| This is a PowerPC 32-bit Linux ABI option. |
| |
| <br><dt><code>-mprototype</code><dt><code>-mno-prototype</code><dd><a name="index-mprototype-2021"></a><a name="index-mno_002dprototype-2022"></a>On System V.4 and embedded PowerPC systems assume that all calls to |
| variable argument functions are properly prototyped. Otherwise, the |
| compiler must insert an instruction before every non-prototyped call to |
| set or clear bit 6 of the condition code register (<var>CR</var>) to |
| indicate whether floating-point values are passed in the floating-point |
| registers in case the function takes variable arguments. With |
| <samp><span class="option">-mprototype</span></samp>, only calls to prototyped variable argument functions |
| set or clear the bit. |
| |
| <br><dt><code>-msim</code><dd><a name="index-msim-2023"></a>On embedded PowerPC systems, assume that the startup module is called |
| <samp><span class="file">sim-crt0.o</span></samp> and that the standard C libraries are <samp><span class="file">libsim.a</span></samp> and |
| <samp><span class="file">libc.a</span></samp>. This is the default for ‘<samp><span class="samp">powerpc-*-eabisim</span></samp>’ |
| configurations. |
| |
| <br><dt><code>-mmvme</code><dd><a name="index-mmvme-2024"></a>On embedded PowerPC systems, assume that the startup module is called |
| <samp><span class="file">crt0.o</span></samp> and the standard C libraries are <samp><span class="file">libmvme.a</span></samp> and |
| <samp><span class="file">libc.a</span></samp>. |
| |
| <br><dt><code>-mads</code><dd><a name="index-mads-2025"></a>On embedded PowerPC systems, assume that the startup module is called |
| <samp><span class="file">crt0.o</span></samp> and the standard C libraries are <samp><span class="file">libads.a</span></samp> and |
| <samp><span class="file">libc.a</span></samp>. |
| |
| <br><dt><code>-myellowknife</code><dd><a name="index-myellowknife-2026"></a>On embedded PowerPC systems, assume that the startup module is called |
| <samp><span class="file">crt0.o</span></samp> and the standard C libraries are <samp><span class="file">libyk.a</span></samp> and |
| <samp><span class="file">libc.a</span></samp>. |
| |
| <br><dt><code>-mvxworks</code><dd><a name="index-mvxworks-2027"></a>On System V.4 and embedded PowerPC systems, specify that you are |
| compiling for a VxWorks system. |
| |
| <br><dt><code>-memb</code><dd><a name="index-memb-2028"></a>On embedded PowerPC systems, set the <var>PPC_EMB</var> bit in the ELF flags |
| header to indicate that ‘<samp><span class="samp">eabi</span></samp>’ extended relocations are used. |
| |
| <br><dt><code>-meabi</code><dt><code>-mno-eabi</code><dd><a name="index-meabi-2029"></a><a name="index-mno_002deabi-2030"></a>On System V.4 and embedded PowerPC systems do (do not) adhere to the |
| Embedded Applications Binary Interface (EABI), which is a set of |
| modifications to the System V.4 specifications. Selecting <samp><span class="option">-meabi</span></samp> |
| means that the stack is aligned to an 8-byte boundary, a function |
| <code>__eabi</code> is called from <code>main</code> to set up the EABI |
| environment, and the <samp><span class="option">-msdata</span></samp> option can use both <code>r2</code> and |
| <code>r13</code> to point to two separate small data areas. Selecting |
| <samp><span class="option">-mno-eabi</span></samp> means that the stack is aligned to a 16-byte boundary, |
| no EABI initialization function is called from <code>main</code>, and the |
| <samp><span class="option">-msdata</span></samp> option only uses <code>r13</code> to point to a single |
| small data area. The <samp><span class="option">-meabi</span></samp> option is on by default if you |
| configured GCC using one of the ‘<samp><span class="samp">powerpc*-*-eabi*</span></samp>’ options. |
| |
| <br><dt><code>-msdata=eabi</code><dd><a name="index-msdata_003deabi-2031"></a>On System V.4 and embedded PowerPC systems, put small initialized |
| <code>const</code> global and static data in the ‘<samp><span class="samp">.sdata2</span></samp>’ section, which |
| is pointed to by register <code>r2</code>. Put small initialized |
| non-<code>const</code> global and static data in the ‘<samp><span class="samp">.sdata</span></samp>’ section, |
| which is pointed to by register <code>r13</code>. Put small uninitialized |
| global and static data in the ‘<samp><span class="samp">.sbss</span></samp>’ section, which is adjacent to |
| the ‘<samp><span class="samp">.sdata</span></samp>’ section. The <samp><span class="option">-msdata=eabi</span></samp> option is |
| incompatible with the <samp><span class="option">-mrelocatable</span></samp> option. The |
| <samp><span class="option">-msdata=eabi</span></samp> option also sets the <samp><span class="option">-memb</span></samp> option. |
| |
| <br><dt><code>-msdata=sysv</code><dd><a name="index-msdata_003dsysv-2032"></a>On System V.4 and embedded PowerPC systems, put small global and static |
| data in the ‘<samp><span class="samp">.sdata</span></samp>’ section, which is pointed to by register |
| <code>r13</code>. Put small uninitialized global and static data in the |
| ‘<samp><span class="samp">.sbss</span></samp>’ section, which is adjacent to the ‘<samp><span class="samp">.sdata</span></samp>’ section. |
| The <samp><span class="option">-msdata=sysv</span></samp> option is incompatible with the |
| <samp><span class="option">-mrelocatable</span></samp> option. |
| |
| <br><dt><code>-msdata=default</code><dt><code>-msdata</code><dd><a name="index-msdata_003ddefault-2033"></a><a name="index-msdata-2034"></a>On System V.4 and embedded PowerPC systems, if <samp><span class="option">-meabi</span></samp> is used, |
| compile code the same as <samp><span class="option">-msdata=eabi</span></samp>, otherwise compile code the |
| same as <samp><span class="option">-msdata=sysv</span></samp>. |
| |
| <br><dt><code>-msdata=data</code><dd><a name="index-msdata_003ddata-2035"></a>On System V.4 and embedded PowerPC systems, put small global |
| data in the ‘<samp><span class="samp">.sdata</span></samp>’ section. Put small uninitialized global |
| data in the ‘<samp><span class="samp">.sbss</span></samp>’ section. Do not use register <code>r13</code> |
| to address small data however. This is the default behavior unless |
| other <samp><span class="option">-msdata</span></samp> options are used. |
| |
| <br><dt><code>-msdata=none</code><dt><code>-mno-sdata</code><dd><a name="index-msdata_003dnone-2036"></a><a name="index-mno_002dsdata-2037"></a>On embedded PowerPC systems, put all initialized global and static data |
| in the ‘<samp><span class="samp">.data</span></samp>’ section, and all uninitialized data in the |
| ‘<samp><span class="samp">.bss</span></samp>’ section. |
| |
| <br><dt><code>-mblock-move-inline-limit=</code><var>num</var><dd><a name="index-mblock_002dmove_002dinline_002dlimit-2038"></a>Inline all block moves (such as calls to <code>memcpy</code> or structure |
| copies) less than or equal to <var>num</var> bytes. The minimum value for |
| <var>num</var> is 32 bytes on 32-bit targets and 64 bytes on 64-bit |
| targets. The default value is target-specific. |
| |
| <br><dt><code>-G </code><var>num</var><dd><a name="index-G-2039"></a><a name="index-smaller-data-references-_0028PowerPC_0029-2040"></a><a name="index-g_t_002esdata_002f_002esdata2-references-_0028PowerPC_0029-2041"></a>On embedded PowerPC systems, put global and static items less than or |
| equal to <var>num</var> bytes into the small data or BSS sections instead of |
| the normal data or BSS section. By default, <var>num</var> is 8. The |
| <samp><span class="option">-G </span><var>num</var></samp> switch is also passed to the linker. |
| All modules should be compiled with the same <samp><span class="option">-G </span><var>num</var></samp> value. |
| |
| <br><dt><code>-mregnames</code><dt><code>-mno-regnames</code><dd><a name="index-mregnames-2042"></a><a name="index-mno_002dregnames-2043"></a>On System V.4 and embedded PowerPC systems do (do not) emit register |
| names in the assembly language output using symbolic forms. |
| |
| <br><dt><code>-mlongcall</code><dt><code>-mno-longcall</code><dd><a name="index-mlongcall-2044"></a><a name="index-mno_002dlongcall-2045"></a>By default assume that all calls are far away so that a longer and more |
| expensive calling sequence is required. This is required for calls |
| farther than 32 megabytes (33,554,432 bytes) from the current location. |
| A short call is generated if the compiler knows |
| the call cannot be that far away. This setting can be overridden by |
| the <code>shortcall</code> function attribute, or by <code>#pragma |
| longcall(0)</code>. |
| |
| <p>Some linkers are capable of detecting out-of-range calls and generating |
| glue code on the fly. On these systems, long calls are unnecessary and |
| generate slower code. As of this writing, the AIX linker can do this, |
| as can the GNU linker for PowerPC/64. It is planned to add this feature |
| to the GNU linker for 32-bit PowerPC systems as well. |
| |
| <p>On Darwin/PPC systems, <code>#pragma longcall</code> generates <code>jbsr |
| callee, L42</code>, plus a <dfn>branch island</dfn> (glue code). The two target |
| addresses represent the callee and the branch island. The |
| Darwin/PPC linker prefers the first address and generates a <code>bl |
| callee</code> if the PPC <code>bl</code> instruction reaches the callee directly; |
| otherwise, the linker generates <code>bl L42</code> to call the branch |
| island. The branch island is appended to the body of the |
| calling function; it computes the full 32-bit address of the callee |
| and jumps to it. |
| |
| <p>On Mach-O (Darwin) systems, this option directs the compiler emit to |
| the glue for every direct call, and the Darwin linker decides whether |
| to use or discard it. |
| |
| <p>In the future, GCC may ignore all longcall specifications |
| when the linker is known to generate glue. |
| |
| <br><dt><code>-mtls-markers</code><dt><code>-mno-tls-markers</code><dd><a name="index-mtls_002dmarkers-2046"></a><a name="index-mno_002dtls_002dmarkers-2047"></a>Mark (do not mark) calls to <code>__tls_get_addr</code> with a relocation |
| specifying the function argument. The relocation allows the linker to |
| reliably associate function call with argument setup instructions for |
| TLS optimization, which in turn allows GCC to better schedule the |
| sequence. |
| |
| <br><dt><code>-pthread</code><dd><a name="index-pthread-2048"></a>Adds support for multithreading with the <dfn>pthreads</dfn> library. |
| This option sets flags for both the preprocessor and linker. |
| |
| <br><dt><code>-mrecip</code><dt><code>-mno-recip</code><dd><a name="index-mrecip-2049"></a>This option enables use of the reciprocal estimate and |
| reciprocal square root estimate instructions with additional |
| Newton-Raphson steps to increase precision instead of doing a divide or |
| square root and divide for floating-point arguments. You should use |
| the <samp><span class="option">-ffast-math</span></samp> option when using <samp><span class="option">-mrecip</span></samp> (or at |
| least <samp><span class="option">-funsafe-math-optimizations</span></samp>, |
| <samp><span class="option">-finite-math-only</span></samp>, <samp><span class="option">-freciprocal-math</span></samp> and |
| <samp><span class="option">-fno-trapping-math</span></samp>). Note that while the throughput of the |
| sequence is generally higher than the throughput of the non-reciprocal |
| instruction, the precision of the sequence can be decreased by up to 2 |
| ulp (i.e. the inverse of 1.0 equals 0.99999994) for reciprocal square |
| roots. |
| |
| <br><dt><code>-mrecip=</code><var>opt</var><dd><a name="index-mrecip_003dopt-2050"></a>This option controls which reciprocal estimate instructions |
| may be used. <var>opt</var> is a comma-separated list of options, which may |
| be preceded by a <code>!</code> to invert the option: |
| <code>all</code>: enable all estimate instructions, |
| <code>default</code>: enable the default instructions, equivalent to <samp><span class="option">-mrecip</span></samp>, |
| <code>none</code>: disable all estimate instructions, equivalent to <samp><span class="option">-mno-recip</span></samp>; |
| <code>div</code>: enable the reciprocal approximation instructions for both single and double precision; |
| <code>divf</code>: enable the single-precision reciprocal approximation instructions; |
| <code>divd</code>: enable the double-precision reciprocal approximation instructions; |
| <code>rsqrt</code>: enable the reciprocal square root approximation instructions for both single and double precision; |
| <code>rsqrtf</code>: enable the single-precision reciprocal square root approximation instructions; |
| <code>rsqrtd</code>: enable the double-precision reciprocal square root approximation instructions; |
| |
| <p>So, for example, <samp><span class="option">-mrecip=all,!rsqrtd</span></samp> enables |
| all of the reciprocal estimate instructions, except for the |
| <code>FRSQRTE</code>, <code>XSRSQRTEDP</code>, and <code>XVRSQRTEDP</code> instructions |
| which handle the double-precision reciprocal square root calculations. |
| |
| <br><dt><code>-mrecip-precision</code><dt><code>-mno-recip-precision</code><dd><a name="index-mrecip_002dprecision-2051"></a>Assume (do not assume) that the reciprocal estimate instructions |
| provide higher-precision estimates than is mandated by the PowerPC |
| ABI. Selecting <samp><span class="option">-mcpu=power6</span></samp>, <samp><span class="option">-mcpu=power7</span></samp> or |
| <samp><span class="option">-mcpu=power8</span></samp> automatically selects <samp><span class="option">-mrecip-precision</span></samp>. |
| The double-precision square root estimate instructions are not generated by |
| default on low-precision machines, since they do not provide an |
| estimate that converges after three steps. |
| |
| <br><dt><code>-mveclibabi=</code><var>type</var><dd><a name="index-mveclibabi-2052"></a>Specifies the ABI type to use for vectorizing intrinsics using an |
| external library. The only type supported at present is <code>mass</code>, |
| which specifies to use IBM's Mathematical Acceleration Subsystem |
| (MASS) libraries for vectorizing intrinsics using external libraries. |
| GCC currently emits calls to <code>acosd2</code>, <code>acosf4</code>, |
| <code>acoshd2</code>, <code>acoshf4</code>, <code>asind2</code>, <code>asinf4</code>, |
| <code>asinhd2</code>, <code>asinhf4</code>, <code>atan2d2</code>, <code>atan2f4</code>, |
| <code>atand2</code>, <code>atanf4</code>, <code>atanhd2</code>, <code>atanhf4</code>, |
| <code>cbrtd2</code>, <code>cbrtf4</code>, <code>cosd2</code>, <code>cosf4</code>, |
| <code>coshd2</code>, <code>coshf4</code>, <code>erfcd2</code>, <code>erfcf4</code>, |
| <code>erfd2</code>, <code>erff4</code>, <code>exp2d2</code>, <code>exp2f4</code>, |
| <code>expd2</code>, <code>expf4</code>, <code>expm1d2</code>, <code>expm1f4</code>, |
| <code>hypotd2</code>, <code>hypotf4</code>, <code>lgammad2</code>, <code>lgammaf4</code>, |
| <code>log10d2</code>, <code>log10f4</code>, <code>log1pd2</code>, <code>log1pf4</code>, |
| <code>log2d2</code>, <code>log2f4</code>, <code>logd2</code>, <code>logf4</code>, |
| <code>powd2</code>, <code>powf4</code>, <code>sind2</code>, <code>sinf4</code>, <code>sinhd2</code>, |
| <code>sinhf4</code>, <code>sqrtd2</code>, <code>sqrtf4</code>, <code>tand2</code>, |
| <code>tanf4</code>, <code>tanhd2</code>, and <code>tanhf4</code> when generating code |
| for power7. Both <samp><span class="option">-ftree-vectorize</span></samp> and |
| <samp><span class="option">-funsafe-math-optimizations</span></samp> must also be enabled. The MASS |
| libraries must be specified at link time. |
| |
| <br><dt><code>-mfriz</code><dt><code>-mno-friz</code><dd><a name="index-mfriz-2053"></a>Generate (do not generate) the <code>friz</code> instruction when the |
| <samp><span class="option">-funsafe-math-optimizations</span></samp> option is used to optimize |
| rounding of floating-point values to 64-bit integer and back to floating |
| point. The <code>friz</code> instruction does not return the same value if |
| the floating-point number is too large to fit in an integer. |
| |
| <br><dt><code>-mpointers-to-nested-functions</code><dt><code>-mno-pointers-to-nested-functions</code><dd><a name="index-mpointers_002dto_002dnested_002dfunctions-2054"></a>Generate (do not generate) code to load up the static chain register |
| (<var>r11</var>) when calling through a pointer on AIX and 64-bit Linux |
| systems where a function pointer points to a 3-word descriptor giving |
| the function address, TOC value to be loaded in register <var>r2</var>, and |
| static chain value to be loaded in register <var>r11</var>. The |
| <samp><span class="option">-mpointers-to-nested-functions</span></samp> is on by default. You cannot |
| call through pointers to nested functions or pointers |
| to functions compiled in other languages that use the static chain if |
| you use the <samp><span class="option">-mno-pointers-to-nested-functions</span></samp>. |
| |
| <br><dt><code>-msave-toc-indirect</code><dt><code>-mno-save-toc-indirect</code><dd><a name="index-msave_002dtoc_002dindirect-2055"></a>Generate (do not generate) code to save the TOC value in the reserved |
| stack location in the function prologue if the function calls through |
| a pointer on AIX and 64-bit Linux systems. If the TOC value is not |
| saved in the prologue, it is saved just before the call through the |
| pointer. The <samp><span class="option">-mno-save-toc-indirect</span></samp> option is the default. |
| </dl> |
| |
| </body></html> |
| |
