Binary literals in c36 comments
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RX Options , Previous: RL78 Options , Up: 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 -mpowerpc-gpopt allows GCC to use the optional PowerPC architecture instructions in the General Purpose group, including floating-point square root. Specifying -mpowerpc-gfxopt allows GCC to use the optional PowerPC architecture instructions in the Graphics group, including floating-point select.
The -mpowerpc64 option allows GCC to generate the additional bit instructions that are found in the full PowerPC64 architecture and to treat GPRs as bit, doubleword quantities.
GCC defaults to -mno-powerpc 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. On AIX, the -maltivec and -mpowerpc64 options are not enabled or disabled by the -mcpu option at present because AIX does not have full support for these options. If both are specified, the code generated uses the architecture and registers set by -mcpu , but the scheduling parameters set by -mtune.
Generate PowerPC64 code for the medium model: The TOC and other static data may be up to a total of 4G in size. This is the default for bit Linux. 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 bit address space. 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. That is, element zero identifies the leftmost element in a vector register when targeting a big-endian platform, and identifies the rightmost element in a vector register when targeting a little-endian platform. Generate AltiVec instructions using big-endian element order, regardless of whether the target is big- or little-endian.
This is the default when targeting a big-endian platform. Using this option is currently deprecated. Support for this feature will be removed in GCC 9. By default, these match array element order corresponding to the endianness for the target.
Generate AltiVec instructions using little-endian element order, regardless of whether the target is big- or little-endian. This is the default when targeting a little-endian platform. This option is currently ignored when targeting a big-endian platform. Generate code that allows ld and ld. Generate code that uses a BSS. Enable the use disable of the built-in functions that allow direct access to the cryptographic instructions that were added in version 2. Enable disable the use of the built-in functions that allow direct access to the Hardware Transactional Memory HTM instructions that were added in version 2.
Generate code that keeps does not keeps some integer operations adjacent so that the instructions can be fused together on power8 and later processors.
Generate code that uses does not use the vector and scalar instructions that were added in version 2. Also enable the use of built-in functions that allow more direct access to the vector instructions. Generate code that uses does not use the non-atomic quad word memory instructions. The -mquad-memory option requires use of bit mode.
Generate code that uses does not use the atomic quad word memory instructions. The -mquad-memory-atomic option requires use of bit mode. If you use the ISA 3. Otherwise, if you do not specify to generate ISA 3. The bit environment sets int, long and pointer to 32 bits and generates code that runs on any PowerPC variant. The bit environment sets int to 32 bits and long and pointer to 64 bits, and generates code for PowerPC64, as for -mpowerpc The -mfull-toc option is selected by default.
However, only 16, entries are available in the TOC. 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 -mno-fp-in-toc and -mno-sum-in-toc options.
You may specify one or both of these options. If you still run out of space in the TOC even when you specify both of these options, specify -mminimal-toc instead.
You may wish to use this option only on files that contain less frequently-executed code. Specifying -maix64 implies -mpowerpc64 , while -maix32 disables the bit ABI and implies -mno-powerpc GCC defaults to -maix 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 bit long double value is properly rounded when comparing values and converting to double.
Use XL symbol names for long double support routines. 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. Link an application written to use message passing with special startup code to enable the application to run.
The Parallel Environment does not support threads, so the -mpe option and the -pthread option are incompatible. On bit Darwin, natural alignment is the default, and -malign-power is not supported. Generate code that does not use uses the floating-point register set. Software floating-point emulation is provided if you use the -msoft-float option, and pass the option to GCC when linking. Generate code for single- or double-precision floating-point operations.
Do not generate sqrt and div instructions for hardware floating-point unit. Specify type of floating-point unit. Generate code that uses does not use the load multiple word instructions and the store multiple word instructions.
Do not use -mmultiple on little-endian PowerPC systems, since those instructions do not work when the processor is in little-endian mode.
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 -mno-update , 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.
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. 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. Generate code that uses does not use the half-word multiply and multiply-accumulate instructions on the IBM , , and processors. These instructions are generated by default when targeting those processors.
This instruction is generated by default when targeting those processors. For example, by default a structure containing nothing but 8 unsigned bit-fields of length 1 is aligned to a 4-byte boundary and has a size of 4 bytes. By using -mno-bit-align , the structure is aligned to a 1-byte boundary and is 1 byte in size. 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. For this to work, all objects linked together must be compiled with -mrelocatable or -mrelocatable-lib. Like -mrelocatable , -mrelocatable-lib generates a. Objects compiled with -mrelocatable-lib may be linked with objects compiled with any combination of the -mrelocatable options.
The -mlittle-endian option is the same as -mlittle. The -mbig-endian option is the same as -mbig. 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. 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.
This option controls the priority that is assigned to dispatch-slot restricted instructions during the second scheduling pass. This option controls which dependences are considered costly by the target during instruction scheduling. This option controls which NOP insertion scheme is used during the second scheduling pass. The argument scheme takes one of the following values:. 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. Insert number NOPs to force an insn to a new group. Select the type of traceback table. Extend the current ABI with a particular extension, or remove such extension.