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Fix PR7156. If the sources of a REG_SEQUENCE are all IMPLICIT_DEF's. Replace it with an IMPLICIT_DEF rather than deleting it or else it would be left without a def.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103984 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng
2010-05-17 22:09:49 +00:00
parent 47006be498
commit 44bfdd3d78
2 changed files with 57 additions and 2 deletions
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13
lib/CodeGen/TwoAddressInstructionPass.cpp
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@ -1238,6 +1238,7 @@ bool TwoAddressInstructionPass::EliminateRegSequences() {
llvm_unreachable(0);
}
bool IsImpDef = true;
SmallVector<unsigned, 4> RealSrcs;
SmallSet<unsigned, 4> Seen;
for (unsigned i = 1, e = MI->getNumOperands(); i < e; i += 2) {
@ -1253,6 +1254,7 @@ bool TwoAddressInstructionPass::EliminateRegSequences() {
DefMI->eraseFromParent();
continue;
}
IsImpDef = false;
// Remember EXTRACT_SUBREG sources. These might be candidate for
// coalescing.
@ -1297,8 +1299,15 @@ bool TwoAddressInstructionPass::EliminateRegSequences() {
UpdateRegSequenceSrcs(SrcReg, DstReg, SubIdx, MRI);
}
DEBUG(dbgs() << "Eliminated: " << *MI);
MI->eraseFromParent();
if (IsImpDef) {
DEBUG(dbgs() << "Turned: " << *MI << " into an IMPLICIT_DEF");
MI->setDesc(TII->get(TargetOpcode::IMPLICIT_DEF));
for (int j = MI->getNumOperands() - 1, ee = 0; j > ee; --j)
MI->RemoveOperand(j);
} else {
DEBUG(dbgs() << "Eliminated: " << *MI);
MI->eraseFromParent();
}
// Try coalescing some EXTRACT_SUBREG instructions.
CoalesceExtSubRegs(RealSrcs, DstReg);