[PATCH] D156185: [clang][ConstExprEmitter] handle ArrayToPointerDecay ImplicitCastExpr of StringLiterals

[Nick Desaulniers via Phabricator via cfe-commits]

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Consider the following statement:

  const char* foo = "foo";

For the sub-AST:

  `-ImplicitCastExpr <col:19> 'const char *' <NoOp>
    `-ImplicitCastExpr <col:19> 'char *' <ArrayToPointerDecay>
      `-StringLiteral <col:19> 'char[4]' lvalue "foo"

The address of the StringLiteral can be emitted as the Constant.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D156185

Files:
  clang/lib/CodeGen/CGExprConstant.cpp


Index: clang/lib/CodeGen/CGExprConstant.cpp
===================================================================
--- clang/lib/CodeGen/CGExprConstant.cpp
+++ clang/lib/CodeGen/CGExprConstant.cpp
@@ -1133,6 +1133,10 @@
           return CGM.EmitNullConstant(destType);
       return nullptr;
     }
+    case CK_ArrayToPointerDecay:
+      if (const auto *S = dyn_cast<StringLiteral>(subExpr))
+        return CGM.GetAddrOfConstantStringFromLiteral(S).getPointer();
+      return nullptr;
 
     case CK_IntToOCLSampler:
       llvm_unreachable("global sampler variables are not generated");
@@ -1171,7 +1175,6 @@
     case CK_CPointerToObjCPointerCast:
     case CK_BlockPointerToObjCPointerCast:
     case CK_AnyPointerToBlockPointerCast:
-    case CK_ArrayToPointerDecay:
     case CK_FunctionToPointerDecay:
     case CK_BaseToDerived:
     case CK_DerivedToBase:



Index: clang/lib/CodeGen/CGExprConstant.cpp
===================================================================
--- clang/lib/CodeGen/CGExprConstant.cpp
+++ clang/lib/CodeGen/CGExprConstant.cpp
@@ -1133,6 +1133,10 @@
           return CGM.EmitNullConstant(destType);
       return nullptr;
     }
+    case CK_ArrayToPointerDecay:
+      if (const auto *S = dyn_cast<StringLiteral>(subExpr))
+        return CGM.GetAddrOfConstantStringFromLiteral(S).getPointer();
+      return nullptr;
 
     case CK_IntToOCLSampler:
       llvm_unreachable("global sampler variables are not generated");
@@ -1171,7 +1175,6 @@
     case CK_CPointerToObjCPointerCast:
     case CK_BlockPointerToObjCPointerCast:
     case CK_AnyPointerToBlockPointerCast:
-    case CK_ArrayToPointerDecay:
     case CK_FunctionToPointerDecay:
     case CK_BaseToDerived:
     case CK_DerivedToBase:

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