From d7ba46b287c29f8b188a6515f3911bb7817a455d Mon Sep 17 00:00:00 2001 From: Yaron Keren Date: Sat, 19 Apr 2014 13:47:43 +0000 Subject: Patch by Vadim Chugunov Win64 stack unwinder gets confused when execution flow "falls through" after a call to 'noreturn' function. This fixes the "missing epilogue" problem by emitting a trap instruction for IR 'unreachable' on x86_x64-pc-windows. A secondary use for it would be for anyone wanting to make double-sure that 'noreturn' functions, indeed, do not return. llvm-svn: 206684 --- llvm/lib/CodeGen/SelectionDAG/FastISel.cpp | 6 ++++-- llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp | 5 +++++ llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h | 2 +- 3 files changed, 10 insertions(+), 3 deletions(-) (limited to 'llvm/lib/CodeGen/SelectionDAG') diff --git a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp index 09563fd368b..a5b72748e2f 100644 --- a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp @@ -1041,8 +1041,10 @@ FastISel::SelectOperator(const User *I, unsigned Opcode) { } case Instruction::Unreachable: - // Nothing to emit. - return true; + if (TM.Options.TrapUnreachable) + return FastEmit_(MVT::Other, MVT::Other, ISD::TRAP) != 0; + else + return true; case Instruction::Alloca: // FunctionLowering has the static-sized case covered. diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp index 06cd8b31c8b..1aaac5fc3c3 100644 --- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp @@ -2765,6 +2765,11 @@ void SelectionDAGBuilder::visitIndirectBr(const IndirectBrInst &I) { getValue(I.getAddress()))); } +void SelectionDAGBuilder::visitUnreachable(const UnreachableInst &I) { + if (DAG.getTarget().Options.TrapUnreachable) + DAG.setRoot(DAG.getNode(ISD::TRAP, getCurSDLoc(), MVT::Other, DAG.getRoot())); +} + void SelectionDAGBuilder::visitFSub(const User &I) { // -0.0 - X --> fneg Type *Ty = I.getType(); diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h index 290d83a608e..a04108d56ad 100644 --- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h +++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h @@ -642,7 +642,7 @@ private: void visitBr(const BranchInst &I); void visitSwitch(const SwitchInst &I); void visitIndirectBr(const IndirectBrInst &I); - void visitUnreachable(const UnreachableInst &I) { /* noop */ } + void visitUnreachable(const UnreachableInst &I); // Helpers for visitSwitch bool handleSmallSwitchRange(CaseRec& CR, -- cgit v1.2.3