[OpenCL] Fix an infinite loop in builidng AddrSpaceQualType (#92612)

In building AddrSpaceQualType
(#90048), there is a bug in
removeAddrSpaceQualType() for arrays. Arrays are weird because
qualifiers on the element type also count as qualifiers on the type, so
getSingleStepDesugaredType() can't remove the sugar on arrays. This
results in an infinite loop in removeAddrSpaceQualType. To fix the
issue, we use ASTContext::getUnqualifiedArrayType instead, which strips
the qualifier off the element type, then reconstruct the array type.

Author: changpeng

clang/include/clang/AST/ASTContext.h

@@ -2611,7 +2611,7 @@ class ASTContext : public RefCountedBase<ASTContext> {
   ///
   /// \returns if this is an array type, the completely unqualified array type
   /// that corresponds to it. Otherwise, returns T.getUnqualifiedType().
-  QualType getUnqualifiedArrayType(QualType T, Qualifiers &Quals);
+  QualType getUnqualifiedArrayType(QualType T, Qualifiers &Quals) const;
 
   /// Determine whether the given types are equivalent after
   /// cvr-qualifiers have been removed.

clang/lib/AST/ASTContext.cpp

@@ -3054,21 +3054,27 @@ QualType ASTContext::removeAddrSpaceQualType(QualType T) const {
   if (!T.hasAddressSpace())
     return T;
 
-  // If we are composing extended qualifiers together, merge together
-  // into one ExtQuals node.
   QualifierCollector Quals;
   const Type *TypeNode;
+  // For arrays, strip the qualifier off the element type, then reconstruct the
+  // array type
+  if (T.getTypePtr()->isArrayType()) {
+    T = getUnqualifiedArrayType(T, Quals);
+    TypeNode = T.getTypePtr();
+  } else {
+    // If we are composing extended qualifiers together, merge together
+    // into one ExtQuals node.
+    while (T.hasAddressSpace()) {
+      TypeNode = Quals.strip(T);
+
+      // If the type no longer has an address space after stripping qualifiers,
+      // jump out.
+      if (!QualType(TypeNode, 0).hasAddressSpace())
+        break;
 
-  while (T.hasAddressSpace()) {
-    TypeNode = Quals.strip(T);
-
-    // If the type no longer has an address space after stripping qualifiers,
-    // jump out.
-    if (!QualType(TypeNode, 0).hasAddressSpace())
-      break;
-
-    // There might be sugar in the way. Strip it and try again.
-    T = T.getSingleStepDesugaredType(*this);
+      // There might be sugar in the way. Strip it and try again.
+      T = T.getSingleStepDesugaredType(*this);
+    }
   }
 
   Quals.removeAddressSpace();
@@ -6093,7 +6099,7 @@ CanQualType ASTContext::getCanonicalParamType(QualType T) const {
 }
 
 QualType ASTContext::getUnqualifiedArrayType(QualType type,
-                                             Qualifiers &quals) {
+                                             Qualifiers &quals) const {
   SplitQualType splitType = type.getSplitUnqualifiedType();
 
   // FIXME: getSplitUnqualifiedType() actually walks all the way to

clang/test/CodeGenOpenCLCXX/array-type-infinite-loop.clcpp

@@ -0,0 +1,25 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --version 4
+//RUN: %clang_cc1 %s -triple spir -emit-llvm -O1 -o - | FileCheck %s
+
+// CHECK-LABEL: define dso_local spir_kernel void @test(
+// CHECK-SAME: ptr addrspace(1) nocapture noundef readonly align 8 [[IN:%.*]], ptr addrspace(1) nocapture noundef writeonly align 8 [[OUT:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] !kernel_arg_addr_space [[META3:![0-9]+]] !kernel_arg_access_qual [[META4:![0-9]+]] !kernel_arg_type [[META5:![0-9]+]] !kernel_arg_base_type [[META5]] !kernel_arg_type_qual [[META6:![0-9]+]] {
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    [[ARRAYIDX1:%.*]] = getelementptr inbounds i8, ptr addrspace(1) [[IN]], i32 8
+// CHECK-NEXT:    [[TMP0:%.*]] = load i64, ptr addrspace(1) [[ARRAYIDX1]], align 8, !tbaa [[TBAA7:![0-9]+]]
+// CHECK-NEXT:    store i64 [[TMP0]], ptr addrspace(1) [[OUT]], align 8, !tbaa [[TBAA7]]
+// CHECK-NEXT:    ret void
+//
+__kernel void test(__global long *In, __global long *Out) {
+   long m[4] = {  In[0], In[1], 0, 0 };
+   *Out = m[1];
+}
+//.
+// CHECK: [[META3]] = !{i32 1, i32 1}
+// CHECK: [[META4]] = !{!"none", !"none"}
+// CHECK: [[META5]] = !{!"long*", !"long*"}
+// CHECK: [[META6]] = !{!"", !""}
+// CHECK: [[TBAA7]] = !{[[META8:![0-9]+]], [[META8]], i64 0}
+// CHECK: [[META8]] = !{!"long", [[META9:![0-9]+]], i64 0}
+// CHECK: [[META9]] = !{!"omnipotent char", [[META10:![0-9]+]], i64 0}
+// CHECK: [[META10]] = !{!"Simple C++ TBAA"}
+//.