[PATCH] D76438: ConstantExpr cached APValues if present for constant evaluation

[Wyatt Childers via Phabricator via cfe-commits]

wchilders created this revision.
wchilders added reviewers: Tyker, rsmith.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

This patch allows the constant evaluator to use `APValueResult`s from `ConstantExpr`s.

There are some outstanding concerns I'll mark with inline comments.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D76438

Files:
  clang/include/clang/AST/Expr.h
  clang/lib/AST/Expr.cpp
  clang/lib/AST/ExprConstant.cpp


Index: clang/lib/AST/ExprConstant.cpp
===================================================================
--- clang/lib/AST/ExprConstant.cpp
+++ clang/lib/AST/ExprConstant.cpp
@@ -6751,8 +6751,13 @@
     return Error(E);
   }
 
-  bool VisitConstantExpr(const ConstantExpr *E)
-    { return StmtVisitorTy::Visit(E->getSubExpr()); }
+  bool VisitConstantExpr(const ConstantExpr *E) {
+    if (E->hasAPValueResult())
+      return DerivedSuccess(E->getAPValueResult(), E);
+
+    return StmtVisitorTy::Visit(E->getSubExpr());
+  }
+
   bool VisitParenExpr(const ParenExpr *E)
     { return StmtVisitorTy::Visit(E->getSubExpr()); }
   bool VisitUnaryExtension(const UnaryOperator *E)
@@ -7317,6 +7322,16 @@
     return true;
   }
 
+  bool VisitConstantExpr(const ConstantExpr *E) {
+    if (E->hasAPValueResult()) {
+      APValue Result = E->getAPValueResult();
+      if (Result.isLValue())
+        return Success(Result, E);
+    }
+
+    return ExprEvaluatorBaseTy::Visit(E->getSubExpr());
+  }
+
   bool VisitMemberExpr(const MemberExpr *E) {
     // Handle non-static data members.
     QualType BaseTy;
Index: clang/lib/AST/Expr.cpp
===================================================================
--- clang/lib/AST/Expr.cpp
+++ clang/lib/AST/Expr.cpp
@@ -356,6 +356,8 @@
 }
 
 APValue ConstantExpr::getAPValueResult() const {
+  assert(hasAPValueResult());
+
   switch (ConstantExprBits.ResultKind) {
   case ConstantExpr::RSK_APValue:
     return APValueResult();
@@ -2870,9 +2872,6 @@
       return CE->getChosenSubExpr();
   }
 
-  else if (auto *CE = dyn_cast<ConstantExpr>(E))
-    return CE->getSubExpr();
-
   return E;
 }
 
Index: clang/include/clang/AST/Expr.h
===================================================================
--- clang/include/clang/AST/Expr.h
+++ clang/include/clang/AST/Expr.h
@@ -1063,6 +1063,9 @@
   bool isImmediateInvocation() const {
     return ConstantExprBits.IsImmediateInvocation;
   }
+  bool hasAPValueResult() const {
+    return ConstantExprBits.APValueKind != APValue::None;
+  }
   APValue getAPValueResult() const;
   APValue &getResultAsAPValue() const { return APValueResult(); }
   llvm::APSInt getResultAsAPSInt() const;


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