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R600: Optimize and cleanup KILL on SI

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We shouldn't insert KILL optimization if we don't have a
kill instruction at all.

Patch by: Christian König

Tested-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Tom Stellard <thomas.stellard@amd.com>
Signed-off-by: Christian König <deathsimple@vodafone.de>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172845 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Tom Stellard
2013-01-18 21:15:50 +00:00
parent 956f13440a
commit 935a91540b
4 changed files with 96 additions and 71 deletions
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127
lib/Target/R600/SILowerControlFlow.cpp
View File

@ -68,7 +68,10 @@ private:
static char ID;
const TargetInstrInfo *TII;
void Skip(MachineInstr &MI, MachineOperand &To);
bool shouldSkip(MachineBasicBlock *From, MachineBasicBlock *To);
void Skip(MachineInstr &From, MachineOperand &To);
void SkipIfDead(MachineInstr &MI);
void If(MachineInstr &MI);
void Else(MachineInstr &MI);
@ -78,6 +81,7 @@ private:
void Loop(MachineInstr &MI);
void EndCf(MachineInstr &MI);
void Kill(MachineInstr &MI);
void Branch(MachineInstr &MI);
public:
@ -100,22 +104,29 @@ FunctionPass *llvm::createSILowerControlFlowPass(TargetMachine &tm) {
return new SILowerControlFlowPass(tm);
}
void SILowerControlFlowPass::Skip(MachineInstr &From, MachineOperand &To) {
bool SILowerControlFlowPass::shouldSkip(MachineBasicBlock *From,
MachineBasicBlock *To) {
unsigned NumInstr = 0;
for (MachineBasicBlock *MBB = *From.getParent()->succ_begin();
NumInstr < SkipThreshold && MBB != To.getMBB() && !MBB->succ_empty();
for (MachineBasicBlock *MBB = From; MBB != To && !MBB->succ_empty();
MBB = *MBB->succ_begin()) {
for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
NumInstr < SkipThreshold && I != E; ++I) {
if (I->isBundle() || !I->isBundled())
++NumInstr;
if (++NumInstr >= SkipThreshold)
return true;
}
}
if (NumInstr < SkipThreshold)
return false;
}
void SILowerControlFlowPass::Skip(MachineInstr &From, MachineOperand &To) {
if (!shouldSkip(*From.getParent()->succ_begin(), To.getMBB()))
return;
DebugLoc DL = From.getDebugLoc();
@ -124,6 +135,38 @@ void SILowerControlFlowPass::Skip(MachineInstr &From, MachineOperand &To) {
.addReg(AMDGPU::EXEC);
}
void SILowerControlFlowPass::SkipIfDead(MachineInstr &MI) {
MachineBasicBlock &MBB = *MI.getParent();
DebugLoc DL = MI.getDebugLoc();
if (!shouldSkip(&MBB, &MBB.getParent()->back()))
return;
MachineBasicBlock::iterator Insert = &MI;
++Insert;
// If the exec mask is non-zero, skip the next two instructions
BuildMI(MBB, Insert, DL, TII->get(AMDGPU::S_CBRANCH_EXECNZ))
.addImm(3)
.addReg(AMDGPU::EXEC);
// Exec mask is zero: Export to NULL target...
BuildMI(MBB, Insert, DL, TII->get(AMDGPU::EXP))
.addImm(0)
.addImm(0x09) // V_008DFC_SQ_EXP_NULL
.addImm(0)
.addImm(1)
.addImm(1)
.addReg(AMDGPU::SREG_LIT_0)
.addReg(AMDGPU::SREG_LIT_0)
.addReg(AMDGPU::SREG_LIT_0)
.addReg(AMDGPU::SREG_LIT_0);
// ... and terminate wavefront
BuildMI(MBB, Insert, DL, TII->get(AMDGPU::S_ENDPGM));
}
void SILowerControlFlowPass::If(MachineInstr &MI) {
MachineBasicBlock &MBB = *MI.getParent();
DebugLoc DL = MI.getDebugLoc();
@ -242,8 +285,28 @@ void SILowerControlFlowPass::Branch(MachineInstr &MI) {
assert(0);
}
void SILowerControlFlowPass::Kill(MachineInstr &MI) {
MachineBasicBlock &MBB = *MI.getParent();
DebugLoc DL = MI.getDebugLoc();
// Kill is only allowed in pixel shaders
MachineFunction &MF = *MBB.getParent();
SIMachineFunctionInfo *Info = MF.getInfo<SIMachineFunctionInfo>();
assert(Info->ShaderType == ShaderType::PIXEL);
// Clear this pixel from the exec mask if the operand is negative
BuildMI(MBB, &MI, DL, TII->get(AMDGPU::V_CMPX_LE_F32_e32), AMDGPU::VCC)
.addReg(AMDGPU::SREG_LIT_0)
.addOperand(MI.getOperand(0));
MI.eraseFromParent();
}
bool SILowerControlFlowPass::runOnMachineFunction(MachineFunction &MF) {
bool HaveCf = false;
bool HaveKill = false;
unsigned Depth = 0;
for (MachineFunction::iterator BI = MF.begin(), BE = MF.end();
BI != BE; ++BI) {
@ -257,6 +320,7 @@ bool SILowerControlFlowPass::runOnMachineFunction(MachineFunction &MF) {
switch (MI.getOpcode()) {
default: break;
case AMDGPU::SI_IF:
++Depth;
If(MI);
break;
@ -277,14 +341,26 @@ bool SILowerControlFlowPass::runOnMachineFunction(MachineFunction &MF) {
break;
case AMDGPU::SI_LOOP:
++Depth;
Loop(MI);
break;
case AMDGPU::SI_END_CF:
HaveCf = true;
if (--Depth == 0 && HaveKill) {
SkipIfDead(MI);
HaveKill = false;
}
EndCf(MI);
break;
case AMDGPU::SI_KILL:
if (Depth == 0)
SkipIfDead(MI);
else
HaveKill = true;
Kill(MI);
break;
case AMDGPU::S_BRANCH:
Branch(MI);
break;
@ -292,40 +368,5 @@ bool SILowerControlFlowPass::runOnMachineFunction(MachineFunction &MF) {
}
}
// TODO: What is this good for?
unsigned ShaderType = MF.getInfo<SIMachineFunctionInfo>()->ShaderType;
if (HaveCf && ShaderType == ShaderType::PIXEL) {
for (MachineFunction::iterator BI = MF.begin(), BE = MF.end();
BI != BE; ++BI) {
MachineBasicBlock &MBB = *BI;
if (MBB.succ_empty()) {
MachineInstr &MI = *MBB.getFirstNonPHI();
DebugLoc DL = MI.getDebugLoc();
// If the exec mask is non-zero, skip the next two instructions
BuildMI(MBB, &MI, DL, TII->get(AMDGPU::S_CBRANCH_EXECNZ))
.addImm(3)
.addReg(AMDGPU::EXEC);
// Exec mask is zero: Export to NULL target...
BuildMI(MBB, &MI, DL, TII->get(AMDGPU::EXP))
.addImm(0)
.addImm(0x09) // V_008DFC_SQ_EXP_NULL
.addImm(0)
.addImm(1)
.addImm(1)
.addReg(AMDGPU::SREG_LIT_0)
.addReg(AMDGPU::SREG_LIT_0)
.addReg(AMDGPU::SREG_LIT_0)
.addReg(AMDGPU::SREG_LIT_0);
// ... and terminate wavefront
BuildMI(MBB, &MI, DL, TII->get(AMDGPU::S_ENDPGM));
}
}
}
return true;
}