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

1 files changed, 3 insertions, 6 deletions

diff --git a/clang/lib/StaticAnalyzer/Checkers/MallocOverflowSecurityChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/MallocOverflowSecurityChecker.cpp
index 4e45a37fd89..fc2ab1d6e3f 100644
--- a/clang/lib/StaticAnalyzer/Checkers/MallocOverflowSecurityChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/MallocOverflowSecurityChecker.cpp
@@ -135,9 +135,9 @@ private:
     bool isIntZeroExpr(const Expr *E) const {
       if (!E->getType()->isIntegralOrEnumerationType())
         return false;
-      Expr::EvalResult Result;
+      llvm::APSInt Result;
       if (E->EvaluateAsInt(Result, Context))
-        return Result.Val.getInt() == 0;
+        return Result == 0;
       return false;
     }
 
@@ -191,11 +191,8 @@ private:
       if (const BinaryOperator *BOp = dyn_cast<BinaryOperator>(rhse)) {
         if (BOp->getOpcode() == BO_Div) {
           const Expr *denom = BOp->getRHS()->IgnoreParenImpCasts();
-          Expr::EvalResult Result;
-          if (denom->EvaluateAsInt(Result, Context)) {
-            denomVal = Result.Val.getInt();
+          if (denom->EvaluateAsInt(denomVal, Context))
             denomKnown = true;
-          }
           const Expr *numerator = BOp->getLHS()->IgnoreParenImpCasts();
           if (numerator->isEvaluatable(Context))
             numeratorKnown = true;