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CPU/Recompiler: Emit test/jz instead of bt/jnc for bits < 8 

Likely very slightly faster.
This commit is contained in:
Connor McLaughlin 2020-06-25 01:19:53 +10:00
parent 55a2c73097
commit b00f50c927
1 changed files with 44 additions and 16 deletions
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60
src/core/cpu_recompiler_code_generator_x64.cpp
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@ -1991,26 +1991,54 @@ void CodeGenerator::EmitConditionalBranch(Condition condition, bool invert, Labe
void CodeGenerator::EmitBranchIfBitClear(HostReg reg, RegSize size, u8 bit, LabelType* label) void CodeGenerator::EmitBranchIfBitClear(HostReg reg, RegSize size, u8 bit, LabelType* label)
{ {
switch (size) if (bit < 8)
{ {
case RegSize_8: // same size, probably faster
m_emit->bt(GetHostReg8(reg), bit); switch (size)
m_emit->jnc(*label); {
break; case RegSize_8:
m_emit->test(GetHostReg8(reg), (1u << bit));
m_emit->jz(*label);
break;
case RegSize_16: case RegSize_16:
m_emit->bt(GetHostReg16(reg), bit); m_emit->test(GetHostReg16(reg), (1u << bit));
m_emit->jnc(*label); m_emit->jz(*label);
break; break;
case RegSize_32: case RegSize_32:
m_emit->bt(GetHostReg32(reg), bit); m_emit->test(GetHostReg32(reg), (1u << bit));
m_emit->jnc(*label); m_emit->jz(*label);
break; break;
default: default:
UnreachableCode(); UnreachableCode();
break; break;
}
}
else
{
switch (size)
{
case RegSize_8:
m_emit->bt(GetHostReg8(reg), bit);
m_emit->jnc(*label);
break;
case RegSize_16:
m_emit->bt(GetHostReg16(reg), bit);
m_emit->jnc(*label);
break;
case RegSize_32:
m_emit->bt(GetHostReg32(reg), bit);
m_emit->jnc(*label);
break;
default:
UnreachableCode();
break;
}
} }
} }