commit ec2bfb3abb587075216a82709de9d99d2e073d73
author James Price <jrprice@google.com> Thu Jun 01 23:01:56 2023 +0000
committer Dawn LUCI CQ <dawn-scoped@luci-project-accounts.iam.gserviceaccount.com> Thu Jun 01 23:01:56 2023 +0000
tree 1809768a9e680dee167d9df2d437c462379d95dd
parent e2abb623b8dfc2e22f3962038c43c95731e26b0a

[tint] Fix implicit stride in array helper

The element stride may be larger than the element alignment.

Add a test for nested arrays in the IR-based SPIR-V writer which
exposes this bug.

Change-Id: If59e32330eb49ec284487fd38e5c09aeb13de888
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/135580
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: James Price <jrprice@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>

src/tint/type/manager.cc

diff --git a/src/tint/type/manager.cc b/src/tint/type/manager.cc
index 4a98045..136f910 100644
--- a/src/tint/type/manager.cc
+++ b/src/tint/type/manager.cc
@@ -128,15 +128,18 @@
 const type::Array* Manager::array(const type::Type* elem_ty,
                                   uint32_t count,
                                   uint32_t stride /* = 0*/) {
+    uint32_t implicit_stride = utils::RoundUp(elem_ty->Align(), elem_ty->Size());
     if (stride == 0) {
-        stride = elem_ty->Align();
+        stride = implicit_stride;
     }
+    TINT_ASSERT(Type, stride >= implicit_stride);
+
     return Get<type::Array>(/* element type */ elem_ty,
                             /* element count */ Get<ConstantArrayCount>(count),
                             /* array alignment */ elem_ty->Align(),
                             /* array size */ count * stride,
                             /* element stride */ stride,
-                            /* implicit stride */ elem_ty->Align());
+                            /* implicit stride */ implicit_stride);
 }
 
 const type::Array* Manager::runtime_array(const type::Type* elem_ty, uint32_t stride /* = 0 */) {

src/tint/writer/spirv/ir/generator_impl_ir_type_test.cc

diff --git a/src/tint/writer/spirv/ir/generator_impl_ir_type_test.cc b/src/tint/writer/spirv/ir/generator_impl_ir_type_test.cc
index 7b2142c..284d421 100644
--- a/src/tint/writer/spirv/ir/generator_impl_ir_type_test.cc
+++ b/src/tint/writer/spirv/ir/generator_impl_ir_type_test.cc
@@ -149,6 +149,22 @@
     EXPECT_EQ(DumpInstructions(generator_.Module().Annots()), "OpDecorate %1 ArrayStride 16\n");
 }
 
+TEST_F(SpvGeneratorImplTest, Type_Array_NestedArray) {
+    auto* arr = mod.Types().array(mod.Types().array(mod.Types().f32(), 64u), 4u);
+    auto id = generator_.Type(arr);
+    EXPECT_EQ(id, 1u);
+    EXPECT_EQ(DumpTypes(),
+              "%3 = OpTypeFloat 32\n"
+              "%5 = OpTypeInt 32 0\n"
+              "%4 = OpConstant %5 64\n"
+              "%2 = OpTypeArray %3 %4\n"
+              "%6 = OpConstant %5 4\n"
+              "%1 = OpTypeArray %2 %6\n");
+    EXPECT_EQ(DumpInstructions(generator_.Module().Annots()),
+              "OpDecorate %2 ArrayStride 4\n"
+              "OpDecorate %1 ArrayStride 256\n");
+}
+
 TEST_F(SpvGeneratorImplTest, Type_RuntimeArray_DefaultStride) {
     auto* arr = mod.Types().runtime_array(mod.Types().f32());
     auto id = generator_.Type(arr);