Besides removing phi cycles that reduce to a single value, also remove dead
phi cycles. Adjust a few tests to keep dead instructions from being optimized
away. This (together with my previous change for phi cycles) fixes Apple
radar 7627077.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96057 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LLVMTargetMachine.cpp b/lib/CodeGen/LLVMTargetMachine.cpp
index 0223feb..278de02 100644
--- a/lib/CodeGen/LLVMTargetMachine.cpp
+++ b/lib/CodeGen/LLVMTargetMachine.cpp
@@ -295,6 +295,10 @@
printAndVerify(PM, "After Instruction Selection",
/* allowDoubleDefs= */ true);
+ // Optimize PHIs before DCE: removing dead PHI cycles may make more
+ // instructions dead.
+ if (OptLevel != CodeGenOpt::None)
+ PM.add(createOptimizePHIsPass());
// Delete dead machine instructions regardless of optimization level.
PM.add(createDeadMachineInstructionElimPass());
@@ -303,7 +307,6 @@
if (OptLevel != CodeGenOpt::None) {
PM.add(createOptimizeExtsPass());
- PM.add(createOptimizePHIsPass());
if (!DisableMachineLICM)
PM.add(createMachineLICMPass());
if (!DisableMachineSink)