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[PowerPC] Make StartMI ignore COPY like instructions.

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Reviewed By: lkail

Differential Revision: https://reviews.llvm.org/D85659
This commit is contained in:
Chen Zheng 2020-08-10 10:55:22 -04:00
parent d99b7697f1
commit 91c84c2226
3 changed files with 52 additions and 20 deletions
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49
lib/Target/PowerPC/PPCInstrInfo.cpp
View File

@ -2655,22 +2655,35 @@ const unsigned *PPCInstrInfo::getLoadOpcodesForSpillArray() const {
return LoadSpillOpcodesArray[getSpillTarget()];
}
void PPCInstrInfo::fixupIsDeadOrKill(MachineInstr &StartMI, MachineInstr &EndMI,
void PPCInstrInfo::fixupIsDeadOrKill(MachineInstr *StartMI, MachineInstr *EndMI,
unsigned RegNo) const {
// Conservatively clear kill flag for the register if the instructions are in
// different basic blocks and in SSA form, because the kill flag may no longer
// be right. There is no need to bother with dead flags since defs with no
// uses will be handled by DCE.
MachineRegisterInfo &MRI = StartMI.getParent()->getParent()->getRegInfo();
if (MRI.isSSA() && (StartMI.getParent() != EndMI.getParent())) {
MachineRegisterInfo &MRI = StartMI->getParent()->getParent()->getRegInfo();
if (MRI.isSSA() && (StartMI->getParent() != EndMI->getParent())) {
MRI.clearKillFlags(RegNo);
return;
}
// Instructions between [StartMI, EndMI] should be in same basic block.
assert((StartMI.getParent() == EndMI.getParent()) &&
assert((StartMI->getParent() == EndMI->getParent()) &&
"Instructions are not in same basic block");
// If before RA, StartMI may be def through COPY, we need to adjust it to the
// real def. See function getForwardingDefMI.
if (MRI.isSSA()) {
bool Reads, Writes;
std::tie(Reads, Writes) = StartMI->readsWritesVirtualRegister(RegNo);
if (!Reads && !Writes) {
assert(Register::isVirtualRegister(RegNo) &&
"Must be a virtual register");
// Get real def and ignore copies.
StartMI = MRI.getVRegDef(RegNo);
}
}
bool IsKillSet = false;
auto clearOperandKillInfo = [=] (MachineInstr &MI, unsigned Index) {
@ -2683,21 +2696,21 @@ void PPCInstrInfo::fixupIsDeadOrKill(MachineInstr &StartMI, MachineInstr &EndMI,
// Set killed flag for EndMI.
// No need to do anything if EndMI defines RegNo.
int UseIndex =
EndMI.findRegisterUseOperandIdx(RegNo, false, &getRegisterInfo());
EndMI->findRegisterUseOperandIdx(RegNo, false, &getRegisterInfo());
if (UseIndex != -1) {
EndMI.getOperand(UseIndex).setIsKill(true);
EndMI->getOperand(UseIndex).setIsKill(true);
IsKillSet = true;
// Clear killed flag for other EndMI operands related to RegNo. In some
// upexpected cases, killed may be set multiple times for same register
// operand in same MI.
for (int i = 0, e = EndMI.getNumOperands(); i != e; ++i)
for (int i = 0, e = EndMI->getNumOperands(); i != e; ++i)
if (i != UseIndex)
clearOperandKillInfo(EndMI, i);
clearOperandKillInfo(*EndMI, i);
}
// Walking the inst in reverse order (EndMI -> StartMI].
MachineBasicBlock::reverse_iterator It = EndMI;
MachineBasicBlock::reverse_iterator E = EndMI.getParent()->rend();
MachineBasicBlock::reverse_iterator It = *EndMI;
MachineBasicBlock::reverse_iterator E = EndMI->getParent()->rend();
// EndMI has been handled above, skip it here.
It++;
MachineOperand *MO = nullptr;
@ -2723,13 +2736,13 @@ void PPCInstrInfo::fixupIsDeadOrKill(MachineInstr &StartMI, MachineInstr &EndMI,
} else if ((MO = It->findRegisterDefOperand(RegNo, false, true,
&getRegisterInfo()))) {
// No use found, set dead for its def.
assert(&*It == &StartMI && "No new def between StartMI and EndMI.");
assert(&*It == StartMI && "No new def between StartMI and EndMI.");
MO->setIsDead(true);
break;
}
}
if ((&*It) == &StartMI)
if ((&*It) == StartMI)
break;
}
// Ensure RegMo liveness is killed after EndMI.
@ -3860,7 +3873,7 @@ bool PPCInstrInfo::simplifyToLI(MachineInstr &MI, MachineInstr &DefMI,
// ForwardingOperandReg = LI imm1
// y = op2 imm2, ForwardingOperandReg(killed)
if (IsForwardingOperandKilled)
fixupIsDeadOrKill(DefMI, MI, ForwardingOperandReg);
fixupIsDeadOrKill(&DefMI, &MI, ForwardingOperandReg);
LLVM_DEBUG(dbgs() << "With:\n");
LLVM_DEBUG(MI.dump());
@ -3952,9 +3965,9 @@ bool PPCInstrInfo::transformToNewImmFormFedByAdd(
// Update kill flag
if (RegMO->isKill() || IsKilledFor(RegMO->getReg()))
fixupIsDeadOrKill(DefMI, MI, RegMO->getReg());
fixupIsDeadOrKill(&DefMI, &MI, RegMO->getReg());
if (ForwardKilledOperandReg != ~0U)
fixupIsDeadOrKill(DefMI, MI, ForwardKilledOperandReg);
fixupIsDeadOrKill(&DefMI, &MI, ForwardKilledOperandReg);
}
LLVM_DEBUG(dbgs() << "With:\n");
@ -4065,12 +4078,12 @@ bool PPCInstrInfo::transformToImmFormFedByAdd(
// x = ADD reg(killed), imm
// y = XOP 0, x
if (IsFwdFeederRegKilled || RegMO->isKill())
fixupIsDeadOrKill(DefMI, MI, RegMO->getReg());
fixupIsDeadOrKill(&DefMI, &MI, RegMO->getReg());
// Pattern 3:
// ForwardKilledOperandReg = ADD reg, imm
// y = XOP 0, ForwardKilledOperandReg(killed)
if (ForwardKilledOperandReg != ~0U)
fixupIsDeadOrKill(DefMI, MI, ForwardKilledOperandReg);
fixupIsDeadOrKill(&DefMI, &MI, ForwardKilledOperandReg);
LLVM_DEBUG(dbgs() << "With:\n");
LLVM_DEBUG(MI.dump());
@ -4226,7 +4239,7 @@ bool PPCInstrInfo::transformToImmFormFedByLI(MachineInstr &MI,
// ForwardKilledOperandReg = LI imm
// y = XOP reg, ForwardKilledOperandReg(killed)
if (ForwardKilledOperandReg != ~0U)
fixupIsDeadOrKill(DefMI, MI, ForwardKilledOperandReg);
fixupIsDeadOrKill(&DefMI, &MI, ForwardKilledOperandReg);
return true;
}

6
lib/Target/PowerPC/PPCInstrInfo.h
View File

@ -567,14 +567,16 @@ public:
/// up. Before calling this function,
/// 1. Ensure that \p RegNo liveness is killed after instruction \p EndMI.
/// 2. Ensure that there is no new definition between (\p StartMI, \p EndMI)
/// and possible definition for \p RegNo is \p StartMI or \p EndMI.
/// and possible definition for \p RegNo is \p StartMI or \p EndMI. For
/// pre-RA cases, definition may be \p StartMI through COPY, \p StartMI
/// will be adjust to true definition.
/// 3. We can do accurate fixup for the case when all instructions between
/// [\p StartMI, \p EndMI] are in same basic block.
/// 4. For the case when \p StartMI and \p EndMI are not in same basic block,
/// we conservatively clear kill flag for all uses of \p RegNo for pre-RA
/// and for post-RA, we give an assertion as without reaching definition
/// analysis post-RA, \p StartMI and \p EndMI are hard to keep right.
void fixupIsDeadOrKill(MachineInstr &StartMI, MachineInstr &EndMI,
void fixupIsDeadOrKill(MachineInstr *StartMI, MachineInstr *EndMI,
unsigned RegNo) const;
void replaceInstrWithLI(MachineInstr &MI, const LoadImmediateInfo &LII) const;
void replaceInstrOperandWithImm(MachineInstr &MI, unsigned OpNo,

17
test/CodeGen/PowerPC/fixup-kill-dead-flag-crash.mir
View File

@ -19,3 +19,20 @@ body: |
STW killed %4:gprc, %4:gprc, 100
BLR8 implicit $lr8, implicit $rm
...
---
name: test2
#CHECK : name : test2
tracksRegLiveness: true
body: |
bb.0.entry:
liveins: $r3
%0:gprc = COPY $r3
%1:gprc_and_gprc_nor0 = LI 0
; CHECK: dead %2:gprc = COPY %1
%2:gprc = COPY %1:gprc_and_gprc_nor0
; CHECK: %3:gprc = LI 1
%3:gprc = ORI killed %2:gprc, 1
; CHECK: STW killed %3, %0, 100
STW killed %3:gprc, %0:gprc, 100
BLR8 implicit $lr8, implicit $rm
...