[cfe-commits] r89934 - /cfe/trunk/lib/CodeGen/CGExprScalar.cpp

[Sylvere Teissier]

Hi, this commit breaks this test case (infinite loop and finally seg fault)

$cat clang-bug.c
static inline int f(int i)
{
  const int __t = (__t);
}
int g(void)
{
  return f(0);
}


$clang-cc -emit-llvm clang-bug.c -o -
clang-bug.c:5:1: warning: control reaches end of non-void function
}
^
Segmentation fault


Eli Friedman a écrit :
> Author: efriedma
> Date: Wed Nov 25 21:22:21 2009
> New Revision: 89934
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=89934&view=rev
> Log:
> Use the more general Evaluate infrastructure for folding constant DeclRefs
> instead of checking explicitly for an EnumConstantDecl.  This folds references
> to constant integer VarDecls, which has two benefits:
> 
> 1. Slightly smaller emitted code from emitting a constant instead of a load,
> and skipping emitting some constant globals.
> 2. Some code forgets to define static constant member variables; emitting a
> load instead of the value in that case leads to a link error. (Such programs
> are technically not well-formed, but in practice build with g++.)
> 
> 
> Modified:
>     cfe/trunk/lib/CodeGen/CGExprScalar.cpp
> 
> Modified: cfe/trunk/lib/CodeGen/CGExprScalar.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprScalar.cpp?rev=89934&r1=89933&r2=89934&view=diff
> 
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGExprScalar.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGExprScalar.cpp Wed Nov 25 21:22:21 2009
> @@ -141,8 +141,11 @@
>  
>    // l-values.
>    Value *VisitDeclRefExpr(DeclRefExpr *E) {
> -    if (const EnumConstantDecl *EC = dyn_cast<EnumConstantDecl>(E->getDecl()))
> -      return llvm::ConstantInt::get(VMContext, EC->getInitVal());
> +    Expr::EvalResult Result;
> +    if (E->Evaluate(Result, CGF.getContext()) && Result.Val.isInt()) {
> +      assert(!Result.HasSideEffects && "Constant declref with side-effect?!");
> +      return llvm::ConstantInt::get(VMContext, Result.Val.getInt());
> +    }
>      return EmitLoadOfLValue(E);
>    }
>    Value *VisitObjCSelectorExpr(ObjCSelectorExpr *E) {
> @@ -167,21 +170,7 @@
>  
>    Value *VisitArraySubscriptExpr(ArraySubscriptExpr *E);
>    Value *VisitShuffleVectorExpr(ShuffleVectorExpr *E);
> -  Value *VisitMemberExpr(MemberExpr *E) { 
> -    if (const EnumConstantDecl *EC = 
> -          dyn_cast<EnumConstantDecl>(E->getMemberDecl())) {
> -      
> -      // We still need to emit the base.
> -      if (E->isArrow())
> -        CGF.EmitScalarExpr(E->getBase());
> -      else
> -        CGF.EmitLValue(E->getBase());
> -      return llvm::ConstantInt::get(VMContext, EC->getInitVal());
> -    }
> -    
> -    return EmitLoadOfLValue(E);
> -  }
> -    
> +  Value *VisitMemberExpr(MemberExpr *E);
>    Value *VisitExtVectorElementExpr(Expr *E) { return EmitLoadOfLValue(E); }
>    Value *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
>      return EmitLoadOfLValue(E);
> @@ -572,6 +561,17 @@
>    Value* SV = llvm::ConstantVector::get(indices.begin(), indices.size());
>    return Builder.CreateShuffleVector(V1, V2, SV, "shuffle");
>  }
> +Value *ScalarExprEmitter::VisitMemberExpr(MemberExpr *E) {
> +  Expr::EvalResult Result;
> +  if (E->Evaluate(Result, CGF.getContext()) && Result.Val.isInt()) {
> +    if (E->isArrow())
> +      CGF.EmitScalarExpr(E->getBase());
> +    else
> +      EmitLValue(E->getBase());
> +    return llvm::ConstantInt::get(VMContext, Result.Val.getInt());
> +  }
> +  return EmitLoadOfLValue(E);
> +}
>  
>  Value *ScalarExprEmitter::VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
>    TestAndClearIgnoreResultAssign();
> 
> 
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