Correction: It doesn't ignore REX.W, it just happens that default size is 64 bits, and REX.W forces size to 64 bits, so it makes no difference. You could probably make a difference by combining REX.W with the operand size prefix (0x66).
On Mon, Jun 22, 2009 at 10:26 AM, Lasse R.H. Nielsen <l...@chromium.org>wrote: > REX without REX.W may be different from no REX at all, but in this case it > isn't. The push/pop operations ignore REX.W, so the REX prefix is only > necessary for high-bits of registers. We use rex_32 for REX with no REX.W, > although it should perhaps be called rex_default_operand_size :). > > On Mon, Jun 22, 2009 at 10:18 AM, <whe...@chromium.org> wrote: > >> >> >> http://codereview.chromium.org/141032/diff/1/2 >> File src/x64/assembler-x64.cc (right): >> >> http://codereview.chromium.org/141032/diff/1/2#newcode1197 >> Line 1197: emit_rex_64(dst); >> On 2009/06/22 07:52:46, Lasse Reichstein wrote: >> > If REX.W isn't required, we might as well use >> emit_optional_rex_32(dst) >> >> >> It is misleading to the code reader to read rex_32 for an actual 64-bit >> move. Actually, REX without REX.W may be diffrerent than no REX at all. >> >> http://codereview.chromium.org/141032 >> >> >> >> > > > -- > Lasse R.H. Nielsen / l...@chromium.org'Faith without judgement merely > degrades the spirit divine' > > -- Lasse R.H. Nielsen / l...@chromium.org'Faith without judgement merely degrades the spirit divine' --~--~---------~--~----~------------~-------~--~----~ v8-dev mailing list v8-dev@googlegroups.com http://groups.google.com/group/v8-dev -~----------~----~----~----~------~----~------~--~---
