[clang] 8e16e5c - [HLSL] Bug fix crash using Array Parameters when De-sugaring is the same as canonicalizing (#127670)

[via cfe-commits]

Author: Sarah Spall
Date: 2025-02-18T10:49:26-08:00
New Revision: 8e16e5ca23d70b6d21346abfbe292aa7e91dcb2e

URL: https://github.com/llvm/llvm-project/commit/8e16e5ca23d70b6d21346abfbe292aa7e91dcb2e
DIFF: https://github.com/llvm/llvm-project/commit/8e16e5ca23d70b6d21346abfbe292aa7e91dcb2e.diff

LOG: [HLSL] Bug fix crash using Array Parameters when De-sugaring is the same as canonicalizing  (#127670)

Fixes this crash: https://hlsl.godbolt.org/z/9aP74s4bP
Which happens because the de-sugared type is the same as the
canonicalized type.
Check if the de-sugared type is canonical before getting the
ArrayParameterType of the canonical type.
Add AST test to ensure crash doesn't happen.

Added: 
    

Modified: 
    clang/lib/AST/ASTContext.cpp
    clang/test/AST/HLSL/TypdefArrayParam.hlsl

Removed: 
    


################################################################################
diff  --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 7c70534388b4c..4a791316a6269 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -3898,7 +3898,8 @@ QualType ASTContext::getArrayParameterType(QualType Ty) const {
   if (Ty->isArrayParameterType())
     return Ty;
   assert(Ty->isConstantArrayType() && "Ty must be an array type.");
-  const auto *ATy = cast<ConstantArrayType>(Ty.getDesugaredType(*this));
+  QualType DTy = Ty.getDesugaredType(*this);
+  const auto *ATy = cast<ConstantArrayType>(DTy);
   llvm::FoldingSetNodeID ID;
   ATy->Profile(ID, *this, ATy->getElementType(), ATy->getZExtSize(),
                ATy->getSizeExpr(), ATy->getSizeModifier(),
@@ -3910,7 +3911,7 @@ QualType ASTContext::getArrayParameterType(QualType Ty) const {
     return QualType(AT, 0);
 
   QualType Canonical;
-  if (!Ty.isCanonical()) {
+  if (!DTy.isCanonical()) {
     Canonical = getArrayParameterType(getCanonicalType(Ty));
 
     // Get the new insert position for the node we care about.

diff  --git a/clang/test/AST/HLSL/TypdefArrayParam.hlsl b/clang/test/AST/HLSL/TypdefArrayParam.hlsl
index c6ae168f84064..37f7a66de23a1 100644
--- a/clang/test/AST/HLSL/TypdefArrayParam.hlsl
+++ b/clang/test/AST/HLSL/TypdefArrayParam.hlsl
@@ -55,3 +55,14 @@ void call2() {
   uint4 C[2] = {A,A};
   uint32_t D = Accumulate(C);
 }
+
+typedef int Foo[2];
+
+// CHECK-LABEL: call3
+// CHECK: ArraySubscriptExpr {{.*}} 'int' lvalue
+// CHECK-NEXT: ImplicitCastExpr {{.*}} 'int *' <ArrayToPointerDecay>
+// CHECK-NEXT: DeclRefExpr {{.*}} 'int[2]' lvalue ParmVar {{.*}} 'F' 'int[2]'
+// CHECK-NEXT: IntegerLiteral {{.*}} 'int' 0
+int call3(Foo F) {
+  return F[0];
+}