Re-apply bottom-up fast-isel, with fixes. Be very careful to avoid emitting
a DBG_VALUE after a terminator, or emitting any instructions before an EH_LABEL.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107943 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LLVMTargetMachine.cpp b/lib/CodeGen/LLVMTargetMachine.cpp
index d437370..bf3137e 100644
--- a/lib/CodeGen/LLVMTargetMachine.cpp
+++ b/lib/CodeGen/LLVMTargetMachine.cpp
@@ -329,19 +329,15 @@
if (OptLevel != CodeGenOpt::None)
PM.add(createOptimizePHIsPass());
- // Delete dead machine instructions regardless of optimization level.
- //
- // At -O0, fast-isel frequently creates dead instructions.
- //
- // With optimization, dead code should already be eliminated. However
- // there is one known exception: lowered code for arguments that are only
- // used by tail calls, where the tail calls reuse the incoming stack
- // arguments directly (see t11 in test/CodeGen/X86/sibcall.ll).
- PM.add(createDeadMachineInstructionElimPass());
- printAndVerify(PM, "After codegen DCE pass",
- /* allowDoubleDefs= */ true);
-
if (OptLevel != CodeGenOpt::None) {
+ // With optimization, dead code should already be eliminated. However
+ // there is one known exception: lowered code for arguments that are only
+ // used by tail calls, where the tail calls reuse the incoming stack
+ // arguments directly (see t11 in test/CodeGen/X86/sibcall.ll).
+ PM.add(createDeadMachineInstructionElimPass());
+ printAndVerify(PM, "After codegen DCE pass",
+ /* allowDoubleDefs= */ true);
+
PM.add(createOptimizeExtsPass());
if (!DisableMachineLICM)
PM.add(createMachineLICMPass());