Platform-Specific Registers

The tables in this section list platform-specific register names for SPARC architecture, x86 architecture, and AMD64 architecture that can be used in expressions.

SPARC Register Information

The following table lists register information for SPARC architecture.

Register Description $g0 through $g7 Global registers $o0 through $o7 “out” registers $l0 through $l7 “local” registers $i0 through $i7 “in” registers $fp Frame pointer, equivalent to register $i6 $sp Stack pointer, equivalent to register $o6 $y Y register $psr Processor state register $wim Window invalid mask register $tbr Trap base register $pc Program counter $npc Next program counter $f0 through $f31 FPU “f” registers $fsr FPU status register $fq FPU queue

The $f0f1 $f2f3 ... $f30f31 pairs of floating-point registers are treated as having C double type (normally $fN registers are treated as C float type). These pairs can also be referred to as $d0 ... $d30.

The following quad floating-point registers are treated as having C long double type, They are available on SPARC V9 hardware:

$q0 $q4 through $q60

The following pairs of registers, which combine the least significant 32 bits of two registers, are available on SPARC V8+ hardware:

$g0g1 through $g6g7
$o0o1 through $o6o7

The following additional registers are available on SPARC V9 and V8+ hardware:

$xg0 through $xg7
$xo0 through $xo7
$xfsr $tstate $gsr
$f32f33 $f34f35 through $f62f63 ($d32 ... $$d62)

See SPARC Architecture Reference Manual and the SPARC Assembly Language Reference Manual for more information on SPARC registers and addressing.

x86 Register Information

The following table lists register information for x86 architecture.

Register Description $gs Alternate data segment register $fs Alternate data segment register $es Alternate data segment register $ds Data segment register $edi Destination index register $esi Source index register $ebp Frame pointer $esp Stack pointer $ebx General register $edx General register $ecx General register $eax General register $trapno Exception vector number $err Error code for exception $eip Instruction pointer $cs Code segment register $eflags Flags $uesp User stack pointer $ss Stack segment register

Commonly used registers are also aliased to their machine independent names.

Register Description $sp Stack pointer; equivalent of $uesp $pc Program counter; equivalent of $eip $fp Frame pointer; equivalent of $ebp $ps

The following table lists registers for the 80386 lower halves (16 bits).

Register Description $ax General register $cx General register $dx General register $bx General register $si Source index register $di Destination index register $ip Instruction pointer, lower 16 bits $flags Flags, lower 16 bits

The first four 80386 16-bit registers can be split into 8-bit parts, as shown in the following table:

Register Description $al Lower (right) half of register $ax $ah Higher (left) half of register $ax $cl Lower (right) half of register $cx $ch Higher (left) half of register $cx $dl Lower (right) half of register $dx $dh Higher (left) half of register $dx $bl Lower (right) half of register $bx $bh Higher (left) half of register $bx

The following table lists registers for 80387 halves:.

Register Description $fctrl Control register $fstat Status register $ftag Tag register $fip Instruction pointer offset $fcs Code segment selector $fopoff Operand pointer offset $fopsel Operand pointer selector $st0 through $st7 Data registers

AMD64 Register Information

The following table lists r egister information for AMD64 architecture:

Register Description rax General purpose register - argument passing for function calls rbp General purpose register - stack management/frame pointer rbx General purpose register - callee-saved rcx General purpose register - argument passing for function calls rdx General purpose register - argument passing for function calls rsi General purpose register - argument passing for function calls rdi General purpose register - argument passing for function calls rsp General purpose register - stack management/stack pointer r8 General purpose register - argument passing for function calls r9 General purpose register - argument passing for function calls r10 General purpose register - temporary r11 General purpose register - temporary r12 General purpose register - callee-saved r13 General purpose register - callee-saved r14 General purpose register - callee-saved r15 General purpose register - callee-saved rflags Flags register rip Instruction pointer mmx0/st0 64-bit media and floating-point register mmx1/st1 64-bit media and floating-point register mmx2/st2 64-bit media and floating-point register mmx3/st3 64-bit media and floating-point register mmx4/st4 64-bit media and floating-point register mmx5/st5 64-bit media and floating-point register mmx6/st6 64-bit media and floating-point register mmx7/st7 64-bit media and floating-point register xmm0 128-bit media register xmm1 128-bit media register xmm2 128-bit media register xmm3 128-bit media register xmm4 128-bit media register xmm5 128-bit media register xmm6 128-bit media register xmm7 128-bit media register xmm8 128-bit media register xmm9 128-bit media register xmm10 128-bit media register xmm11 128-bit media register xmm12 128-bit media register xmm13 128-bit media register xmm14 128-bit media register xmm15 128-bit media register cs Segment register es Segment register fs Segment register gs Segment register os Segment register ss Segment register fcw fxsave and fxstor memory image control word fsw fxsave and fxstor memory image status word ftw fxsave and fxstor memory image tag word fop fxsave and fxstor memory image last x87 op code frdp fxsave and fxstor memory image 64-bit offset into the date segment frip fxsave and fxstor memory image 64-bit offset into the code segment mxcsr fxsave and fxstor memory image 128 media instruction control and status register mxcsr_mask set bits in mxcsr_mask indicate supported feature bits in mxcsr ymmo 256–bit advanced vector register ymm1 256–bit advanced vector register ymm2 256–bit advanced vector register ymm3 256–bit advanced vector register ymm4 256–bit advanced vector register ymm5 256–bit advanced vector register ymm6 256–bit advanced vector register ymm7 256–bit advanced vector register ymm8 256–bit advanced vector register ymm9 256–bit advanced vector register ymm10 256–bit advanced vector register ymm11 256–bit advanced vector register ymm12 256–bit advanced vector register ymm13 256–bit advanced vector register ymm14 256–bit advanced vector register ymm15 256–bit advanced vector register

The fields of an advanced vector (AVX) register (ymm0 through ymm15) can be treated as having C int, float, or double types.