Correctly handle replacement and removal of PHIs with one incoming register.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54374 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/UnreachableBlockElim.cpp b/lib/CodeGen/UnreachableBlockElim.cpp
index 19341ee..ca682fd 100644
--- a/lib/CodeGen/UnreachableBlockElim.cpp
+++ b/lib/CodeGen/UnreachableBlockElim.cpp
@@ -27,6 +27,7 @@
#include "llvm/Pass.h"
#include "llvm/Type.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Target/TargetInstrInfo.h"
@@ -128,10 +129,15 @@
start->RemoveOperand(i-1);
}
- if (start->getNumOperands() == 1) {
+ if (start->getNumOperands() == 3) {
MachineInstr* phi = start;
+ unsigned Input = phi->getOperand(1).getReg();
+ unsigned Output = phi->getOperand(0).getReg();
+
start++;
phi->eraseFromParent();
+
+ F.getRegInfo().replaceRegWith(Output, Input);
} else
start++;
}