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LibJIT: Encode mov(reg, 0) as xor(reg, reg)

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This uses less space for the same result. :^)
This commit is contained in:
Andreas Kling 2023-10-26 15:24:51 +02:00
parent 5b87d26027
commit d09bc54586
1 changed files with 7 additions and 0 deletions
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7
Userland/Libraries/LibJIT/Assembler.h
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@ -122,6 +122,13 @@ struct Assembler {
} }
if (dst.type == Operand::Type::Reg && src.type == Operand::Type::Imm64) { if (dst.type == Operand::Type::Reg && src.type == Operand::Type::Imm64) {
if (src.offset_or_immediate == 0) {
// xor dst, dst
emit8(0x48 | ((to_underlying(dst.reg) >= 8) ? 1 << 0 : 0));
emit8(0x31);
emit8(0xc0 | (encode_reg(dst.reg) << 3) | encode_reg(dst.reg));
return;
}
emit8(0x48 | ((to_underlying(dst.reg) >= 8) ? 1 << 0 : 0)); emit8(0x48 | ((to_underlying(dst.reg) >= 8) ? 1 << 0 : 0));
emit8(0xb8 | encode_reg(dst.reg)); emit8(0xb8 | encode_reg(dst.reg));
emit64(src.offset_or_immediate); emit64(src.offset_or_immediate);