Commit ea85232c authored by Richard Smith's avatar Richard Smith
Browse files

Don't crash in IRGen if a conditional with 'throw' in one of its branches is 

used as a branch condition.

llvm-svn: 181368
parent 78f05f13

clang/lib/CodeGen/CGException.cpp

+8 −4
Original line number Diff line number Diff line
@@ -419,13 +419,15 @@ llvm::Value *CodeGenFunction::getSelectorFromSlot() { 
  return Builder.CreateLoad(getEHSelectorSlot(), "sel");

}



void CodeGenFunction::EmitCXXThrowExpr(const CXXThrowExpr *E) {

void CodeGenFunction::EmitCXXThrowExpr(const CXXThrowExpr *E,

                                       bool KeepInsertionPoint) {

  if (!E->getSubExpr()) {

    EmitNoreturnRuntimeCallOrInvoke(getReThrowFn(CGM),

                                    ArrayRef<llvm::Value*>());



    // throw is an expression, and the expression emitters expect us

    // to leave ourselves at a valid insertion point.

    if (KeepInsertionPoint)

      EmitBlock(createBasicBlock("throw.cont"));



    return;
@@ -440,6 +442,7 @@ void CodeGenFunction::EmitCXXThrowExpr(const CXXThrowExpr *E) { 
    CGM.getObjCRuntime().EmitThrowStmt(*this, S, false);

    // This will clear insertion point which was not cleared in

    // call to EmitThrowStmt.

    if (KeepInsertionPoint)

      EmitBlock(createBasicBlock("throw.cont"));

    return;

  }
@@ -478,6 +481,7 @@ void CodeGenFunction::EmitCXXThrowExpr(const CXXThrowExpr *E) { 


  // throw is an expression, and the expression emitters expect us

  // to leave ourselves at a valid insertion point.

  if (KeepInsertionPoint)

    EmitBlock(createBasicBlock("throw.cont"));

}

clang/lib/CodeGen/CodeGenFunction.cpp

+10 −0
Original line number Diff line number Diff line
@@ -928,6 +928,16 @@ void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond, 
    return;

  }



  if (const CXXThrowExpr *Throw = dyn_cast<CXXThrowExpr>(Cond)) {

    // Conditional operator handling can give us a throw expression as a

    // condition for a case like:

    //   br(c ? throw x : y, t, f) -> br(c, br(throw x, t, f), br(y, t, f)

    // Fold this to:

    //   br(c, throw x, br(y, t, f))

    EmitCXXThrowExpr(Throw, /*KeepInsertionPoint*/false);

    return;

  }



  // Emit the code with the fully general case.

  llvm::Value *CondV = EvaluateExprAsBool(Cond);

  Builder.CreateCondBr(CondV, TrueBlock, FalseBlock);

clang/lib/CodeGen/CodeGenFunction.h

+1 −1
Original line number Diff line number Diff line
@@ -2708,7 +2708,7 @@ public: 
  }

  void enterNonTrivialFullExpression(const ExprWithCleanups *E);



  void EmitCXXThrowExpr(const CXXThrowExpr *E);

  void EmitCXXThrowExpr(const CXXThrowExpr *E, bool KeepInsertionPoint = true);



  void EmitLambdaExpr(const LambdaExpr *E, AggValueSlot Dest);

clang/test/CodeGenCXX/throw-expressions.cpp

+26 −1
Original line number Diff line number Diff line 
// RUN: %clang_cc1 -fcxx-exceptions -fexceptions -emit-llvm-only -verify %s -Wno-unreachable-code

// RUN: %clang_cc1 -fcxx-exceptions -fexceptions -Wno-unreachable-code -Werror -emit-llvm -o - %s | FileCheck %s

// expected-no-diagnostics



int val = 42;
@@ -19,3 +19,28 @@ void test3() { 
int test4() {

  return 1 ? throw val : val;

}



// PR15923

int test5(bool x, bool y, int z) {

  return (x ? throw 1 : y) ? z : throw 2;

}

// CHECK: define i32 @_Z5test5bbi(

// CHECK: br i1

//

// x.true:

// CHECK: call void @__cxa_throw(

// CHECK-NEXT: unreachable

//

// x.false:

// CHECK: br i1

//

// y.true:

// CHECK: load i32*

// CHECK: br label

//

// y.false:

// CHECK: call void @__cxa_throw(

// CHECK-NEXT: unreachable

//

// end:

// CHECK: ret i32