Revert r347417 "Re-Reinstate 347294 with a fix for the failures."
This caused a miscompile in Chrome (see crbug.com/908372) that's
illustrated by this small reduction:
static bool f(int *a, int *b) {
return !__builtin_constant_p(b - a) || (!(b - a));
}
int arr[] = {1,2,3};
bool g() {
return f(arr, arr + 3);
}
$ clang -O2 -S -emit-llvm a.cc -o -
g() should return true, but after r347417 it became false for some reason.
This also reverts the follow-up commits.
r347417:
> Re-Reinstate 347294 with a fix for the failures.
>
> Don't try to emit a scalar expression for a non-scalar argument to
> __builtin_constant_p().
>
> Third time's a charm!
r347446:
> The result of is.constant() is unsigned.
r347480:
> A __builtin_constant_p() returns 0 with a function type.
r347512:
> isEvaluatable() implies a constant context.
>
> Assume that we're in a constant context if we're asking if the expression can
> be compiled into a constant initializer. This fixes the issue where a
> __builtin_constant_p() in a compound literal was diagnosed as not being
> constant, even though it's always possible to convert the builtin into a
> constant.
r347531:
> A "constexpr" is evaluated in a constant context. Make sure this is reflected
> if a __builtin_constant_p() is a part of a constexpr.
llvm-svn: 347656
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index e343949..ec6f084 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -2594,8 +2594,8 @@
E = NTTP->getReplacement();
continue;
}
- if (FullExpr *FE = dyn_cast<FullExpr>(E)) {
- E = FE->getSubExpr();
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(E)) {
+ E = CE->getSubExpr();
continue;
}
return E;
@@ -2619,8 +2619,8 @@
E = NTTP->getReplacement();
continue;
}
- if (FullExpr *FE = dyn_cast<FullExpr>(E)) {
- E = FE->getSubExpr();
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(E)) {
+ E = CE->getSubExpr();
continue;
}
return E;
@@ -2648,8 +2648,8 @@
= dyn_cast<SubstNonTypeTemplateParmExpr>(E)) {
E = NTTP->getReplacement();
continue;
- } else if (FullExpr *FE = dyn_cast<FullExpr>(E)) {
- E = FE->getSubExpr();
+ } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(E)) {
+ E = CE->getSubExpr();
continue;
}
break;
@@ -2920,12 +2920,6 @@
break;
}
- case ConstantExprClass: {
- // FIXME: We should be able to return "true" here, but it can lead to extra
- // error messages. E.g. in Sema/array-init.c.
- const Expr *Exp = cast<ConstantExpr>(this)->getSubExpr();
- return Exp->isConstantInitializer(Ctx, false, Culprit);
- }
case CompoundLiteralExprClass: {
// This handles gcc's extension that allows global initializers like
// "struct x {int x;} x = (struct x) {};".
@@ -2965,8 +2959,8 @@
const Expr *Elt = ILE->getInit(ElementNo++);
if (Field->isBitField()) {
// Bitfields have to evaluate to an integer.
- EvalResult Result;
- if (!Elt->EvaluateAsInt(Result, Ctx)) {
+ llvm::APSInt ResultTmp;
+ if (!Elt->EvaluateAsInt(ResultTmp, Ctx)) {
if (Culprit)
*Culprit = Elt;
return false;