diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/CodeGen/LLVMTargetMachine.cpp | 20 | ||||
| -rw-r--r-- | lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp | 2 |
2 files changed, 14 insertions, 8 deletions
diff --git a/lib/CodeGen/LLVMTargetMachine.cpp b/lib/CodeGen/LLVMTargetMachine.cpp index bf3137e495..d437370031 100644 --- a/lib/CodeGen/LLVMTargetMachine.cpp +++ b/lib/CodeGen/LLVMTargetMachine.cpp @@ -329,15 +329,19 @@ bool LLVMTargetMachine::addCommonCodeGenPasses(PassManagerBase &PM, if (OptLevel != CodeGenOpt::None) PM.add(createOptimizePHIsPass()); - 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); + // 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) { PM.add(createOptimizeExtsPass()); if (!DisableMachineLICM) PM.add(createMachineLICMPass()); diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp index 073e2964d2..94f0efcb70 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp @@ -709,11 +709,13 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) { FastIS->startNewBlock(BB); // Do FastISel on as many instructions as possible. for (; BI != End; ++BI) { +#if 0 // Defer instructions with no side effects; they'll be emitted // on-demand later. if (BI->isSafeToSpeculativelyExecute() && !FuncInfo->isExportedInst(BI)) continue; +#endif // Try to select the instruction with FastISel. if (FastIS->SelectInstruction(BI)) |