diff options
Diffstat (limited to 'lib/CodeGen/LLVMTargetMachine.cpp')
| -rw-r--r-- | lib/CodeGen/LLVMTargetMachine.cpp | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/lib/CodeGen/LLVMTargetMachine.cpp b/lib/CodeGen/LLVMTargetMachine.cpp index b584704..bf3137e 100644 --- a/lib/CodeGen/LLVMTargetMachine.cpp +++ b/lib/CodeGen/LLVMTargetMachine.cpp @@ -329,12 +329,15 @@ bool LLVMTargetMachine::addCommonCodeGenPasses(PassManagerBase &PM, if (OptLevel != CodeGenOpt::None) PM.add(createOptimizePHIsPass()); - // Delete dead machine instructions regardless of optimization level. - 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()); @@ -358,7 +361,7 @@ bool LLVMTargetMachine::addCommonCodeGenPasses(PassManagerBase &PM, /* allowDoubleDefs= */ true); // Perform register allocation. - PM.add(createRegisterAllocator()); + PM.add(createRegisterAllocator(OptLevel)); printAndVerify(PM, "After Register Allocation"); // Perform stack slot coloring and post-ra machine LICM. |
