diff options
| -rw-r--r-- | lib/Transforms/Utils/SimplifyCFG.cpp | 49 | ||||
| -rw-r--r-- | test/Transforms/SimplifyCFG/2011-09-05-TrivialLPad.ll | 22 |
2 files changed, 71 insertions, 0 deletions
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp index 240f037..b8c3ab4 100644 --- a/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/lib/Transforms/Utils/SimplifyCFG.cpp @@ -63,6 +63,7 @@ class SimplifyCFGOpt { bool FoldValueComparisonIntoPredecessors(TerminatorInst *TI, IRBuilder<> &Builder); + bool SimplifyResume(ResumeInst *RI, IRBuilder<> &Builder); bool SimplifyReturn(ReturnInst *RI, IRBuilder<> &Builder); bool SimplifyUnwind(UnwindInst *UI, IRBuilder<> &Builder); bool SimplifyUnreachable(UnreachableInst *UI); @@ -2138,6 +2139,52 @@ static bool SimplifyBranchOnICmpChain(BranchInst *BI, const TargetData *TD, return true; } +bool SimplifyCFGOpt::SimplifyResume(ResumeInst *RI, IRBuilder<> &Builder) { + // If this is a trivial landing pad that just continues unwinding the caught + // exception then zap the landing pad, turning its invokes into calls. + BasicBlock *BB = RI->getParent(); + LandingPadInst *LPInst = dyn_cast<LandingPadInst>(BB->getFirstNonPHI()); + if (RI->getValue() != LPInst) + // Not a landing pad, or the resume is not unwinding the exception that + // caused control to branch here. + return false; + + // Check that there are no other instructions except for debug intrinsics. + BasicBlock::iterator I = LPInst, E = RI; + while (++I != E) + if (!isa<DbgInfoIntrinsic>(I)) + return false; + + // Turn all invokes that unwind here into calls and delete the basic block. + for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE;) { + InvokeInst *II = cast<InvokeInst>((*PI++)->getTerminator()); + SmallVector<Value*, 8> Args(II->op_begin(), II->op_end() - 3); + // Insert a call instruction before the invoke. + CallInst *Call = CallInst::Create(II->getCalledValue(), Args, "", II); + Call->takeName(II); + Call->setCallingConv(II->getCallingConv()); + Call->setAttributes(II->getAttributes()); + Call->setDebugLoc(II->getDebugLoc()); + + // Anything that used the value produced by the invoke instruction now uses + // the value produced by the call instruction. Note that we do this even + // for void functions and calls with no uses so that the callgraph edge is + // updated. + II->replaceAllUsesWith(Call); + BB->removePredecessor(II->getParent()); + + // Insert a branch to the normal destination right before the invoke. + BranchInst::Create(II->getNormalDest(), II); + + // Finally, delete the invoke instruction! + II->eraseFromParent(); + } + + // The landingpad is now unreachable. Zap it. + BB->eraseFromParent(); + return true; +} + bool SimplifyCFGOpt::SimplifyReturn(ReturnInst *RI, IRBuilder<> &Builder) { BasicBlock *BB = RI->getParent(); if (!BB->getFirstNonPHIOrDbg()->isTerminator()) return false; @@ -2836,6 +2883,8 @@ bool SimplifyCFGOpt::run(BasicBlock *BB) { } else { if (SimplifyCondBranch(BI, Builder)) return true; } + } else if (ResumeInst *RI = dyn_cast<ResumeInst>(BB->getTerminator())) { + if (SimplifyResume(RI, Builder)) return true; } else if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) { if (SimplifyReturn(RI, Builder)) return true; } else if (SwitchInst *SI = dyn_cast<SwitchInst>(BB->getTerminator())) { diff --git a/test/Transforms/SimplifyCFG/2011-09-05-TrivialLPad.ll b/test/Transforms/SimplifyCFG/2011-09-05-TrivialLPad.ll new file mode 100644 index 0000000..7558419 --- /dev/null +++ b/test/Transforms/SimplifyCFG/2011-09-05-TrivialLPad.ll @@ -0,0 +1,22 @@ +; RUN: opt < %s -simplifycfg -S | FileCheck %s + +; CHECK-NOT: invoke +; CHECK-NOT: landingpad + +declare void @bar() + +define i32 @foo() { +entry: + invoke void @bar() + to label %return unwind label %lpad + +return: + ret i32 0 + +lpad: + %lp = landingpad { i8*, i32 } personality i32 (i32, i64, i8*, i8*)* @__gxx_personality_v0 + cleanup + resume { i8*, i32 } %lp +} + +declare i32 @__gxx_personality_v0(i32, i64, i8*, i8*) |