[clang][bytecode] Optimize enum value range checks

[tbaederr]

Only do the work if we really have to.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Timm Baeder (tbaederr)

Changes

Only do the work if we really have to.

---

Full diff: https://github.com/llvm/llvm-project/pull/139672.diff

2 Files Affected:

• (modified) clang/lib/AST/ByteCode/Interp.cpp (+2-3)
• (modified) clang/lib/AST/ByteCode/Interp.h (+3-2)

diff --git a/clang/lib/AST/ByteCode/Interp.cpp b/clang/lib/AST/ByteCode/Interp.cpp
index 43f8d156589b6..91930c016c985 100644
--- a/clang/lib/AST/ByteCode/Interp.cpp
+++ b/clang/lib/AST/ByteCode/Interp.cpp
@@ -1251,12 +1251,11 @@ bool Free(InterpState &S, CodePtr OpPC, bool DeleteIsArrayForm,
 
 void diagnoseEnumValue(InterpState &S, CodePtr OpPC, const EnumDecl *ED,
                        const APSInt &Value) {
-  llvm::APInt Min;
-  llvm::APInt Max;
-
   if (S.EvaluatingDecl && !S.EvaluatingDecl->isConstexpr())
     return;
 
+  llvm::APInt Min;
+  llvm::APInt Max;
   ED->getValueRange(Max, Min);
   --Max;
 
diff --git a/clang/lib/AST/ByteCode/Interp.h b/clang/lib/AST/ByteCode/Interp.h
index a13fd6c1f1daa..35d97167135f7 100644
--- a/clang/lib/AST/ByteCode/Interp.h
+++ b/clang/lib/AST/ByteCode/Interp.h
@@ -3026,10 +3026,11 @@ template <PrimType Name, class T = typename PrimConv<Name>::T>
 inline bool CheckEnumValue(InterpState &S, CodePtr OpPC, const EnumDecl *ED) {
   assert(ED);
   assert(!ED->isFixed());
-  const APSInt Val = S.Stk.peek<T>().toAPSInt();
 
-  if (S.inConstantContext())
+  if (S.inConstantContext()) {
+    const APSInt Val = S.Stk.peek<T>().toAPSInt();
     diagnoseEnumValue(S, OpPC, ED, Val);
+  }
   return true;
 }