[CodeGen] Only consider innermost cast for !heapallocsite

[nikic]

Summary

Without opaque pointers, this code determined !heapallocsite based on the innermost cast of the allocation call. With opaque pointers, the casts no longer generate an instruction, so the outermost cast is used. Add an explicit check for nested casts to prevent this.

clang/lib/CodeGen/CGExprScalar.cpp

if (CGF.CGM.getCodeGenOpts().StrictVTablePointers) {
         // because launder(strip(src)) == launder(src), so there is no need to
         // add extra strip before launder.
         Src = Builder.CreateStripInvariantGroup(Src);
       }
     }
 
     // Update heapallocsite metadata when there is an explicit pointer cast.
     if (auto *CI = dyn_cast<llvm::CallBase>(Src)) {
-      if (CI->getMetadata("heapallocsite") && isa<ExplicitCastExpr>(CE)) {
+      if (CI->getMetadata("heapallocsite") && isa<ExplicitCastExpr>(CE) &&
+          !isa<CastExpr>(E)) {
         QualType PointeeType = DestTy->getPointeeType();
         if (!PointeeType.isNull())
           CGF.getDebugInfo()->addHeapAllocSiteMetadata(CI, PointeeType,
                                                        CE->getExprLoc());
       }
     }
 
     // If Src is a fixed vector and Dst is a scalable vector, and both have the

clang/test/CodeGen/debug-info-codeview-heapallocsite.c

-// RUN: %clang_cc1 -no-opaque-pointers -triple x86_64-windows-msvc -debug-info-kind=limited -gcodeview -fdeclspec -S -emit-llvm %s -o - | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-windows-msvc -debug-info-kind=limited -gcodeview -fdeclspec -S -emit-llvm %s -o - | FileCheck %s
 
 struct Foo;
 struct Bar;
 
 __declspec(allocator) void *alloc_void(void);
 __declspec(allocator) struct Foo *alloc_foo(void);
 
 void call_alloc(void) {
   struct Foo *p = alloc_void();
   struct Foo *w = alloc_foo();
   struct Foo *q = (struct Foo*)alloc_void();
   struct Foo *r = (struct Foo*)(struct Bar*)alloc_void();
 }
 
 // CHECK-LABEL: define {{.*}}void @call_alloc
-// CHECK: call i8* {{.*}}@alloc_void{{.*}} !heapallocsite [[DBG1:!.*]]
-// CHECK: call %struct.Foo* {{.*}}@alloc_foo{{.*}} !heapallocsite [[DBG2:!.*]]
-// CHECK: call i8* {{.*}}@alloc_void{{.*}} !heapallocsite [[DBG2]]
-// CHECK: call i8* {{.*}}@alloc_void{{.*}} !heapallocsite [[DBG3:!.*]]
+// CHECK: call ptr {{.*}}@alloc_void{{.*}} !heapallocsite [[DBG1:!.*]]
+// CHECK: call ptr {{.*}}@alloc_foo{{.*}} !heapallocsite [[DBG2:!.*]]
+// CHECK: call ptr {{.*}}@alloc_void{{.*}} !heapallocsite [[DBG2]]
+// CHECK: call ptr {{.*}}@alloc_void{{.*}} !heapallocsite [[DBG3:!.*]]
 
 // CHECK: [[DBG2]] = !DICompositeType(tag: DW_TAG_structure_type,
 // CHECK-SAME:                                 name: "Foo"
 // CHECK: [[DBG3]] = !DICompositeType(tag: DW_TAG_structure_type,
 // CHECK-SAME:                                 name: "Bar"
 // CHECK: [[DBG1]] = !{}