commit 230657c9f545e987dd6a1477b6142182b68ab8b2
author James Price <jrprice@google.com> Wed May 15 18:56:08 2024 +0000
committer Dawn LUCI CQ <dawn-scoped@luci-project-accounts.iam.gserviceaccount.com> Wed May 15 18:56:08 2024 +0000
tree d837a7bf5d88378cd82033254777dfbfe4da090c
parent ffd6ea417ba0884ef9be550133349fe72bafe516

[ir] Allow access to extract pointers from structs

The validator previously required that only `access` instructions with
a pointer source operand can produce a pointer result. When extracting
a pointer member from a struct value this is not the case, so update
the validation logic to allow for this.

Change-Id: I6c98427746d1cdb98c4d9cf4c61a76dc6ccfbcd4
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/188340
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: James Price <jrprice@google.com>

src/tint/lang/core/ir/validator.cc

diff --git a/src/tint/lang/core/ir/validator.cc b/src/tint/lang/core/ir/validator.cc
index 891fc09..1d69625 100644
--- a/src/tint/lang/core/ir/validator.cc
+++ b/src/tint/lang/core/ir/validator.cc
@@ -992,13 +992,20 @@
 
     auto* want = a->Result(0)->Type();
     auto* want_view = want->As<type::MemoryView>();
-    bool ok = ty == want->UnwrapPtrOrRef() && (obj_view == nullptr) == (want_view == nullptr);
-    if (ok && obj_view) {
-        ok = obj_view->Is<type::Pointer>() == want_view->Is<type::Pointer>() &&
-             obj_view->AddressSpace() == want_view->AddressSpace() &&
-             obj_view->Access() == want_view->Access();
+    bool ok = true;
+    if (obj_view) {
+        // Pointer source always means pointer result.
+        ok = want_view && ty == want_view->StoreType();
+        if (ok) {
+            // Also check that the address space and access modes match.
+            ok = obj_view->Is<type::Pointer>() == want_view->Is<type::Pointer>() &&
+                 obj_view->AddressSpace() == want_view->AddressSpace() &&
+                 obj_view->Access() == want_view->Access();
+        }
+    } else {
+        // Otherwise, result types should exactly match.
+        ok = ty == want;
     }
-
     if (TINT_UNLIKELY(!ok)) {
         AddError(a) << "result of access chain is type " << desc_of(in_kind, ty)
                     << " but instruction type is " << style::Type(want->FriendlyName());

src/tint/lang/core/ir/validator_test.cc

diff --git a/src/tint/lang/core/ir/validator_test.cc b/src/tint/lang/core/ir/validator_test.cc
index b14f6c3..bc6b744 100644
--- a/src/tint/lang/core/ir/validator_test.cc
+++ b/src/tint/lang/core/ir/validator_test.cc
@@ -1114,6 +1114,25 @@
     ASSERT_EQ(res, Success);
 }
 
+TEST_F(IR_ValidatorTest, Access_ExtractPointerFromStruct) {
+    auto* ptr = ty.ptr<private_, i32>();
+    Vector<type::Manager::StructMemberDesc, 1> members{
+        type::Manager::StructMemberDesc{mod.symbols.New("a"), ptr},
+    };
+    auto* str = ty.Struct(mod.symbols.New("MyStruct"), std::move(members));
+    auto* f = b.Function("my_func", ty.void_());
+    auto* obj = b.FunctionParam("obj", str);
+    f->SetParams({obj});
+
+    b.Append(f->Block(), [&] {
+        b.Access(ptr, obj, 0_u);
+        b.Return(f);
+    });
+
+    auto res = ir::Validate(mod);
+    ASSERT_EQ(res, Success);
+}
+
 TEST_F(IR_ValidatorTest, Block_TerminatorInMiddle) {
     auto* f = b.Function("my_func", ty.void_());