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Add small ARM perf experiment. Did not help on ARMv7 so turned it off.

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xsacha might want to try it on ARMv6.
This commit is contained in:
Henrik Rydgard 2013-11-09 12:57:07 +01:00
parent 2fe898cda8
commit 15bc5a8db7
2 changed files with 31 additions and 13 deletions
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37
Core/MIPS/ARM/ArmJit.cpp
View file

@ -57,6 +57,13 @@ void DisassembleArm(const u8 *data, int size) {
namespace MIPSComp
{
ArmJitOptions::ArmJitOptions()
{
enableBlocklink = true;
downcountInRegister = true;
useBackJump = false;
}
Jit::Jit(MIPSState *mips) : blocks(mips, this), gpr(mips, &jo), fpr(mips), mips_(mips)
{
logBlocks = 0;
@ -211,14 +218,28 @@ const u8 *Jit::DoJit(u32 em_address, JitBlock *b)
js.PrefixStart();
// We add a check before the block, used when entering from a linked block.
b->checkedEntry = GetCodePtr();
// Downcount flag check. The last block decremented downcounter, and the flag should still be available.
// Possible idea: Move the MOVI2R and B *before* checkedEntry, and just branch backwards there.
// possible drawback is that branch predictors will predict short backward branches as taken.
SetCC(CC_LT);
MOVI2R(R0, js.blockStart);
B((const void *)outerLoopPCInR0);
SetCC(CC_AL);
if (jo.useBackJump) {
// Moves the MOVI2R and B *before* checkedEntry, and just branch backwards there.
// Speedup seems to be zero unfortunately but I guess it may vary from device to device.
// Not intrusive so keeping it around here to experiment with, may help on ARMv6 due to
// large/slow construction of 32-bit immediates?
JumpTarget backJump = GetCodePtr();
MOVI2R(R0, js.blockStart);
B((const void *)outerLoopPCInR0);
b->checkedEntry = GetCodePtr();
SetCC(CC_LT);
B(backJump);
SetCC(CC_AL);
} else {
b->checkedEntry = GetCodePtr();
// Downcount flag check. The last block decremented downcounter, and the flag should still be available.
SetCC(CC_LT);
MOVI2R(R0, js.blockStart);
B((const void *)outerLoopPCInR0);
SetCC(CC_AL);
}
b->normalEntry = GetCodePtr();
// TODO: this needs work

7
Core/MIPS/ARM/ArmJit.h
View file

@ -34,14 +34,11 @@ namespace MIPSComp
struct ArmJitOptions
{
ArmJitOptions()
{
enableBlocklink = true;
downcountInRegister = true;
}
ArmJitOptions();
bool enableBlocklink;
bool downcountInRegister;
bool useBackJump;
};
class Jit : public ArmGen::ARMXCodeBlock