From 8c79706e89dd2792bcc7b1e44d8f5db6abaf1617 Mon Sep 17 00:00:00 2001
From: Hans Wennborg <hans@hanshq.net>
Date: Tue, 27 Nov 2018 14:01:40 +0000
Subject: 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
---
 clang/lib/Sema/AnalysisBasedWarnings.cpp | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

(limited to 'clang/lib/Sema/AnalysisBasedWarnings.cpp')

diff --git a/clang/lib/Sema/AnalysisBasedWarnings.cpp b/clang/lib/Sema/AnalysisBasedWarnings.cpp
index 3b6cbe9469b..ab46554485f 100644
--- a/clang/lib/Sema/AnalysisBasedWarnings.cpp
+++ b/clang/lib/Sema/AnalysisBasedWarnings.cpp
@@ -1309,10 +1309,11 @@ static bool isInLoop(const ASTContext &Ctx, const ParentMap &PM,
     case Stmt::ObjCForCollectionStmtClass:
       return true;
     case Stmt::DoStmtClass: {
-      Expr::EvalResult Result;
-      if (!cast<DoStmt>(S)->getCond()->EvaluateAsInt(Result, Ctx))
+      const Expr *Cond = cast<DoStmt>(S)->getCond();
+      llvm::APSInt Val;
+      if (!Cond->EvaluateAsInt(Val, Ctx))
         return true;
-      return Result.Val.getInt().getBoolValue();
+      return Val.getBoolValue();
     }
     default:
       break;
-- 
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