Implement `-fvk-use-dx-layout` (#4912)

* Implement `-fvk-use-dx-layout`

Fixes: #4126

Changes:
* Added fvk-use-dx-layout
* Modified `HLSLConstantBufferLayoutRulesImpl` for correctness (ex: Array is always 16 byte aligned)
* Added kFXCShaderResourceLayoutRulesFamilyImpl and kFXCConstantBufferLayoutRulesFamilyImpl to handle fvk-use-dx-layout
* Added `ConstantBufferLayoutRules` to manage constant buffer rules
* Added `alignCompositeElementOfNonAggregate`/`alignCompositeElementOfAggregate` to handle forced alignment of composites for ConstantBuffers
* `StructuredBuffer` rules are mostly equal to `scalar` layout, not much was needed to be changed to support this behavior.

* seperate legacy constant buffer and how Slang does constant-buffer normally

* undo an addition

* remove accidental test

* Address review and fix

Address review and remove GLSL support since GLSL requires a seperate legalization (need to linearlize structs like with `legalizeMetalIR` to assign explicit offsets)

* comments

* remove aggregate and non-aggregate logic

We don't need this distinction for the logic

---------

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

1 files changed, 11 insertions, 0 deletions

diff --git a/source/slang/slang-options.cpp b/source/slang/slang-options.cpp
index 33103442d..12b32998f 100644
--- a/source/slang/slang-options.cpp
+++ b/source/slang/slang-options.cpp
@@ -400,6 +400,7 @@ void initCommandOptions(CommandOptions& options)
         { OptionKind::GLSLForceScalarLayout,
          "-force-glsl-scalar-layout,-fvk-use-scalar-layout", nullptr,
          "Make data accessed through ConstantBuffer, ParameterBlock, StructuredBuffer, ByteAddressBuffer and general pointers follow the 'scalar' layout when targeting GLSL or SPIRV."},
+        { OptionKind::ForceDXLayout, "-fvk-use-dx-layout", nullptr, "Pack members using FXCs member packing rules when targeting GLSL or SPIRV." },
         { OptionKind::VulkanBindShift, vkShiftNames.getBuffer(), "-fvk-<vulkan-shift>-shift <N> <space>", 
         "For example '-fvk-b-shift <N> <space>' shifts by N the inferred binding numbers for all resources in 'b' registers of space <space>. "
         "For a resource attached with :register(bX, <space>) but not [vk::binding(...)], "
@@ -2054,6 +2055,11 @@ SlangResult OptionsParser::_parse(
                 getCurrentTarget()->optionSet.add(CompilerOptionName::GLSLForceScalarLayout, true);
                 break;
             }
+            case OptionKind::ForceDXLayout:
+            {
+                getCurrentTarget()->optionSet.add(CompilerOptionName::ForceDXLayout, true);
+                break;
+            }
             case OptionKind::EnableEffectAnnotations:
             {
                 m_compileRequest->setEnableEffectAnnotations(true);
@@ -2780,6 +2786,11 @@ SlangResult OptionsParser::_parse(
                 m_compileRequest->setTargetForceGLSLScalarBufferLayout(targetID, true);
             }
 
+            if (rawTarget.optionSet.shouldUseDXLayout())
+            {
+                m_compileRequest->setTargetForceDXLayout(targetID, true);
+            }
+
             if (rawTarget.optionSet.getBoolOption(CompilerOptionName::GenerateWholeProgram))
             {
                 m_compileRequest->setTargetGenerateWholeProgram(targetID, true);