Address structured buffer `GetDimensions` issues for WGSL, GLSL and SPIRV (#7010)

* Fix structured buffer get dimensions

* Further fixes and added tests

* Remove unnecessary include

* Fix test issues

* attempt to fix wgpu crash

* test remove half usage in test

* attempt to fix WGPU test issue

* Another attempt to fix WGSL test - make test similar to the existing GetDimensions test

---------

Co-authored-by: Yong He <yonghe@outlook.com>

3 files changed, 35 insertions, 11 deletions

diff --git a/source/slang/slang-emit-glsl.cpp b/source/slang/slang-emit-glsl.cpp
index 116d9b1d6..a8ce6564c 100644
--- a/source/slang/slang-emit-glsl.cpp
+++ b/source/slang/slang-emit-glsl.cpp
@@ -2790,11 +2790,12 @@ bool GLSLSourceEmitter::tryEmitInstStmtImpl(IRInst* inst)
             auto elementType =
                 as<IRHLSLStructuredBufferTypeBase>(inst->getOperand(0)->getDataType())
                     ->getElementType();
-            IRIntegerValue stride = 0;
-            if (auto sizeDecor = elementType->findDecoration<IRSizeAndAlignmentDecoration>())
-            {
-                stride = align(sizeDecor->getSize(), (int)sizeDecor->getAlignment());
-            }
+
+            // The element type should have a `SizeAndAlignment` decoration created during lowering.
+            auto sizeDecor = elementType->findDecoration<IRSizeAndAlignmentDecoration>();
+            SLANG_ASSERT(sizeDecor);
+            const auto stride = align(sizeDecor->getSize(), (int)sizeDecor->getAlignment());
+
             m_writer->emit(stride);
             m_writer->emit(");\n");
             return true;
diff --git a/source/slang/slang-emit-spirv.cpp b/source/slang/slang-emit-spirv.cpp
index 7d202c7c1..54417899c 100644
--- a/source/slang/slang-emit-spirv.cpp
+++ b/source/slang/slang-emit-spirv.cpp
@@ -6878,12 +6878,21 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
             kResultID,
             inst->getOperand(0),
             SpvLiteralInteger::from32(0));
-        auto elementType = as<IRPtrType>(inst->getOperand(0)->getDataType())->getValueType();
-        IRIntegerValue stride = 0;
-        if (auto sizeDecor = elementType->findDecoration<IRSizeAndAlignmentDecoration>())
-        {
-            stride = align(sizeDecor->getSize(), (int)sizeDecor->getAlignment());
-        }
+
+        // The buffer is a global parameter, so it's a pointer
+        auto bufPtrType = cast<IRPtrTypeBase>(inst->getOperand(0)->getDataType());
+        // It's lowered to a struct type..
+        auto bufType = cast<IRStructType>(bufPtrType->getValueType());
+        // containing an unsized array, specifically one with an explicit
+        // stride, which is not expressible in spirv_asm blocks
+        auto arrayType = cast<IRArrayTypeBase>(bufType->getFields().getFirst()->getFieldType());
+
+        // The element type should have a `SizeAndAlignment` decoration created during lowering.
+        auto sizeDecor =
+            arrayType->getElementType()->findDecoration<IRSizeAndAlignmentDecoration>();
+        SLANG_ASSERT(sizeDecor);
+        const auto stride = align(sizeDecor->getSize(), (int)sizeDecor->getAlignment());
+
         auto strideOperand = emitIntConstant(stride, builder.getUIntType());
         auto result =
             emitOpCompositeConstruct(parent, inst, inst->getDataType(), arrayLength, strideOperand);
diff --git a/source/slang/slang-ir-lower-buffer-element-type.cpp b/source/slang/slang-ir-lower-buffer-element-type.cpp
index 1294b400d..ed0a3b309 100644
--- a/source/slang/slang-ir-lower-buffer-element-type.cpp
+++ b/source/slang/slang-ir-lower-buffer-element-type.cpp
@@ -939,11 +939,25 @@ struct LoweredElementTypeContext
                 }
             }
             if (auto structBuffer = as<IRHLSLStructuredBufferTypeBase>(globalInst))
+            {
                 elementType = structBuffer->getElementType();
+                auto config = getTypeLoweringConfigForBuffer(target, structBuffer);
+
+                // Create size and alignment decoration for potential use
+                // in`StructuredBufferGetDimensions`.
+                IRSizeAndAlignment sizeAlignment;
+                getSizeAndAlignment(
+                    target->getOptionSet(),
+                    config.layoutRule,
+                    elementType,
+                    &sizeAlignment);
+                SLANG_UNUSED(sizeAlignment);
+            }
             else if (auto constBuffer = as<IRUniformParameterGroupType>(globalInst))
                 elementType = constBuffer->getElementType();
             else if (auto storageBuffer = as<IRGLSLShaderStorageBufferType>(globalInst))
                 elementType = storageBuffer->getElementType();
+
             if (as<IRTextureBufferType>(globalInst))
                 continue;
             if (!as<IRStructType>(elementType) && !as<IRMatrixType>(elementType) &&