diff options
Diffstat (limited to 'erts/emulator/beam/jit/x86/instr_common.cpp')
| -rw-r--r-- | erts/emulator/beam/jit/x86/instr_common.cpp | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/erts/emulator/beam/jit/x86/instr_common.cpp b/erts/emulator/beam/jit/x86/instr_common.cpp index e0dd4d792b..8d046db40e 100644 --- a/erts/emulator/beam/jit/x86/instr_common.cpp +++ b/erts/emulator/beam/jit/x86/instr_common.cpp @@ -25,10 +25,15 @@ * one byte shorter than instructions that use 64-bits registers * (e.g. rax). This does not apply to registers r8-r15 beacuse they'll * always need a rex prefix. The `and`, `or`, and `cmp` instructions - * are even shorter than operating on the RETb (al) register. The + * are even shorter when operating on the RETb (al) register. The * `test` instruction with an immediate second operand is shorter * when operating on an 8-bit register. * + * When loading an immediate value to a register, storing to the + * 32-bit register in one or two bytes shorter than storing to + * the corresponding 64-bit register. The mov_imm() helper + * will automatically choose the shortest instruction. + * * On both Unix and Windows, instructions can be shortened by using * RETd, ARG1d, or ARG2d instead of RET, ARG1, or ARG2, respectively. * On Unix, but not on Windows, ARG3d and ARG4d will also result in |