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author | Owen Anderson <resistor@mac.com> | 2008-08-06 20:29:20 +0000 |
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committer | Owen Anderson <resistor@mac.com> | 2008-08-06 20:29:20 +0000 |
commit | 9860b71b6a23bc0ae620d7dfc621ea1ffafbf8d8 (patch) | |
tree | 98a2a1052556a0fdbb14d7a5b9bbe8d3ef573a46 /lib/CodeGen/StrongPHIElimination.cpp | |
parent | 9b49120408e6c0e10e18ce38cae7120c954fe708 (diff) | |
download | external_llvm-9860b71b6a23bc0ae620d7dfc621ea1ffafbf8d8.zip external_llvm-9860b71b6a23bc0ae620d7dfc621ea1ffafbf8d8.tar.gz external_llvm-9860b71b6a23bc0ae620d7dfc621ea1ffafbf8d8.tar.bz2 |
We don't need to try to coalesce input vregs that are the same as the output vreg.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54422 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen/StrongPHIElimination.cpp')
-rw-r--r-- | lib/CodeGen/StrongPHIElimination.cpp | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/lib/CodeGen/StrongPHIElimination.cpp b/lib/CodeGen/StrongPHIElimination.cpp index b276e80..11b8ca3 100644 --- a/lib/CodeGen/StrongPHIElimination.cpp +++ b/lib/CodeGen/StrongPHIElimination.cpp @@ -421,6 +421,7 @@ void StrongPHIElimination::processBlock(MachineBasicBlock* MBB) { while (P != MBB->end() && P->getOpcode() == TargetInstrInfo::PHI) { unsigned DestReg = P->getOperand(0).getReg(); + // Don't both doing PHI elimination for dead PHI's. if (P->registerDefIsDead(DestReg)) { ++P; @@ -442,6 +443,12 @@ void StrongPHIElimination::processBlock(MachineBasicBlock* MBB) { // Iterate over the operands of the PHI node for (int i = P->getNumOperands() - 1; i >= 2; i-=2) { unsigned SrcReg = P->getOperand(i-1).getReg(); + + // Don't need to try to coalesce a register with itself. + if (SrcReg == DestReg) { + ProcessedNames.insert(SrcReg); + continue; + } // Check for trivial interferences via liveness information, allowing us // to avoid extra work later. Any registers that interfere cannot both |