[clang] b4343ab - [clang][ExprConst] Short-circuit ConstantExpr evaluation

[Timm Bäder via cfe-commits]

Author: Timm Bäder
Date: 2023-10-10T13:27:03+02:00
New Revision: b4343aba9fa12ddb397e08208ec37fcf0fb93864

URL: https://github.com/llvm/llvm-project/commit/b4343aba9fa12ddb397e08208ec37fcf0fb93864
DIFF: https://github.com/llvm/llvm-project/commit/b4343aba9fa12ddb397e08208ec37fcf0fb93864.diff

LOG: [clang][ExprConst] Short-circuit ConstantExpr evaluation

ConstantExprs already have a value attached we can just return here.

Differential Revision: https://reviews.llvm.org/D155548

Added: 
    

Modified: 
    clang/lib/AST/ExprConstant.cpp

Removed: 
    


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diff  --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 5a33e918db8e8c0..e5539dedec02a4b 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -15327,6 +15327,17 @@ static bool FastEvaluateAsRValue(const Expr *Exp, Expr::EvalResult &Result,
     return true;
   }
 
+  if (const auto *CE = dyn_cast<ConstantExpr>(Exp)) {
+    if (CE->hasAPValueResult()) {
+      Result.Val = CE->getAPValueResult();
+      IsConst = true;
+      return true;
+    }
+
+    // The SubExpr is usually just an IntegerLiteral.
+    return FastEvaluateAsRValue(CE->getSubExpr(), Result, Ctx, IsConst);
+  }
+
   // This case should be rare, but we need to check it before we check on
   // the type below.
   if (Exp->getType().isNull()) {