Index: lib/Transforms/Utils/SimplifyCFG.cpp =================================================================== --- lib/Transforms/Utils/SimplifyCFG.cpp +++ lib/Transforms/Utils/SimplifyCFG.cpp @@ -2903,26 +2903,71 @@ // exception then zap the landing pad, turning its invokes into calls. BasicBlock *BB = RI->getParent(); LandingPadInst *LPInst = dyn_cast(BB->getFirstNonPHI()); - if (RI->getValue() != LPInst) - // Not a landing pad, or the resume is not unwinding the exception that - // caused control to branch here. + + // If RI->getValue() is a landing pad, check if the first instruction is + // the same landing pad that caused control to branch here. If RI->getValue + // is a phi of landing pad, check its predecessor blocks to see if any of + // them contains a trivial landing pad. + if (RI->getValue() != LPInst && !isa(RI->getValue())) return false; - // Check that there are no other instructions except for debug intrinsics. - BasicBlock::iterator I = LPInst, E = RI; + // Check that there are no other instructions except for debug intrinsics + // between the landing pad (or phi of landing pad) and resume instruction. + BasicBlock::iterator I = cast(RI->getValue()), E = RI; while (++I != E) if (!isa(I)) return false; + SmallVector TrivialUnwindBlocks; + if (RI->getValue() == LPInst) { + // Landing pad is in current block, which has already been checked. + TrivialUnwindBlocks.push_back(BB); + } else { + // Check incoming blocks to see if any of them are trivial. + auto *PhiLPInst = cast(RI->getValue()); + for (unsigned i = 0; i < PhiLPInst->getNumIncomingValues(); i++) { + auto *IncomingBB = PhiLPInst->getIncomingBlock(i); + auto *IncomingLP = PhiLPInst->getIncomingValue(i); + + auto *LandingPad = + dyn_cast(IncomingBB->getFirstNonPHI()); + // Not the landing pad that caused the control to branch here. + if (IncomingLP != LandingPad) + continue; + + bool isTrivial = true; + + I = IncomingBB->getFirstNonPHI(); + E = IncomingBB->getTerminator(); + while (++I != E) + if (!isa(I)) { + isTrivial = false; + break; + } + + if (isTrivial) + TrivialUnwindBlocks.push_back(IncomingBB); + } + } + // 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;) { - BasicBlock *Pred = *PI++; - removeUnwindEdge(Pred); + for (auto TrivialBB : TrivialUnwindBlocks) { + if (auto *Phi = dyn_cast(RI->getValue())) { + // Blocks those would be deleted should also be removed + // from the phi node. + Phi->removeIncomingValue(TrivialBB); + } + + for (pred_iterator PI = pred_begin(TrivialBB), PE = pred_end(TrivialBB); PI != PE;) { + BasicBlock *Pred = *PI++; + removeUnwindEdge(Pred); + } + + // The landingpad is now unreachable. Zap it. + TrivialBB->eraseFromParent(); } - // The landingpad is now unreachable. Zap it. - BB->eraseFromParent(); - return true; + return TrivialUnwindBlocks.size() != 0; } bool SimplifyCFGOpt::SimplifyCleanupReturn(CleanupReturnInst *RI) { Index: test/Transforms/SimplifyCFG/invoke_unwind.ll =================================================================== --- test/Transforms/SimplifyCFG/invoke_unwind.ll +++ test/Transforms/SimplifyCFG/invoke_unwind.ll @@ -17,4 +17,47 @@ resume { i8*, i32 } %exn } + +declare i64 @dummy1() +declare i64 @dummy2() + +; This testcase checks to see if simplifycfg pass can convert two invoke +; instructions to call instructions if they share a common trivial unwind +; block. +define i64 @test2(i1 %cond) personality i32 (...)* @__gxx_personality_v0 { +entry: +; CHECK-LABEL: @test2( +; CHECK: %call1 = call i64 @dummy1() +; CHECK: %call2 = call i64 @dummy2() +; CHECK-NOT: resume { i8*, i32 } %lp + br i1 %cond, label %br1, label %br2 + +br1: + %call1 = invoke i64 @dummy1() + to label %invoke.cont unwind label %lpad1 + +br2: + %call2 = invoke i64 @dummy2() + to label %invoke.cont unwind label %lpad2 + +invoke.cont: + %c = phi i64 [%call1, %br1], [%call2, %br2] + ret i64 %c + + +lpad1: + %0 = landingpad { i8*, i32 } + cleanup + br label %rethrow + +lpad2: + %1 = landingpad { i8*, i32 } + cleanup + br label %rethrow + +rethrow: + %lp = phi { i8*, i32 } [%0, %lpad1], [%1, %lpad2] + resume { i8*, i32 } %lp +} + declare i32 @__gxx_personality_v0(...)