Fix a case where debug_value could affect codegen.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94866 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/RegAllocLocal.cpp b/lib/CodeGen/RegAllocLocal.cpp
index cbb5826..6a09bd9 100644
--- a/lib/CodeGen/RegAllocLocal.cpp
+++ b/lib/CodeGen/RegAllocLocal.cpp
@@ -838,6 +838,18 @@
}
}
+ // If a DEBUG_VALUE says something is located in a spilled register,
+ // change the DEBUG_VALUE to be undef, which prevents the register
+ // from being reloaded here. Doing that would change the generated
+ // code, unless another use immediately follows this instruction.
+ if (MI->getOpcode()==TargetInstrInfo::DEBUG_VALUE &&
+ MI->getNumOperands()==3 && MI->getOperand(0).isReg()) {
+ unsigned VirtReg = MI->getOperand(0).getReg();
+ if (VirtReg && TargetRegisterInfo::isVirtualRegister(VirtReg) &&
+ !getVirt2PhysRegMapSlot(VirtReg))
+ MI->getOperand(0).setReg(0U);
+ }
+
// Get the used operands into registers. This has the potential to spill
// incoming values if we are out of registers. Note that we completely
// ignore physical register uses here. We assume that if an explicit