Only run CoalesceExtSubRegs when we can expect LiveIntervalAnalysis to clean up
the inserted INSERT_SUBREGs after us.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106345 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/TwoAddressInstructionPass.cpp b/lib/CodeGen/TwoAddressInstructionPass.cpp
index 048b669..14102d1 100644
--- a/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -1397,8 +1397,11 @@
MI->eraseFromParent();
}
- // Try coalescing some EXTRACT_SUBREG instructions.
- CoalesceExtSubRegs(RealSrcs, DstReg);
+ // Try coalescing some EXTRACT_SUBREG instructions. This can create
+ // INSERT_SUBREG instructions that must have <undef> flags added by
+ // LiveIntervalAnalysis, so only run it when LiveVariables is available.
+ if (LV)
+ CoalesceExtSubRegs(RealSrcs, DstReg);
}
RegSequences.clear();