Reviewers: Kasper Lund, Description: Added some peephole optimizaitions regarding push of immediate followed by pop eax.
Please review this at http://codereview.chromium.org/4212 Affected files: M src/assembler-ia32.cc Index: src/assembler-ia32.cc =================================================================== --- src/assembler-ia32.cc (revision 360) +++ src/assembler-ia32.cc (working copy) @@ -469,7 +469,48 @@ } return; } + } else if (instr == 0x6a && dst.is(eax)) { // push of immediate 8 bit + byte imm8 = last_pc_[1]; + if (imm8 == 0) { + // 6a00 push 0x0 + // 58 pop eax + last_pc_[0] = 0x31; + last_pc_[1] = 0xc0; + // change to + // 31c0 xor eax,eax + last_pc_ = NULL; + return; + } else { + // 6a00 push 0xXX + // 58 pop eax + last_pc_[0] = 0xb8; + EnsureSpace ensure_space(this); + if ((imm8 & 0x80) != 0) { + EMIT(0xff); + EMIT(0xff); + EMIT(0xff); + // change to + // b8XXffffff mov eax,0xffffffXX + } else { + EMIT(0x00); + EMIT(0x00); + EMIT(0x00); + // change to + // b8XX000000 mov eax,0x000000XX + } + last_pc_ = NULL; + return; + } + } else if (instr == 0x68 && dst.is(eax)) { // push of immediate 32 bit + // 68XXXXXXXX push 0xXXXXXXXX + // 58 pop eax + last_pc_[0] = 0xb8; + last_pc_ = NULL; + // change to + // b8XXXXXXXX mov eax,0xXXXXXXXX + return; } + // Other potential patterns for peephole: // 0x712716 102 890424 mov [esp], eax // 0x712719 105 8b1424 mov edx, [esp] --~--~---------~--~----~------------~-------~--~----~ v8-dev mailing list v8-dev@googlegroups.com http://groups.google.com/group/v8-dev -~----------~----~----~----~------~----~------~--~---
