From e1c6fecd90142761aaecbf4e281beb87893fc531 Mon Sep 17 00:00:00 2001
From: ArielG-NV <159081215+ArielG-NV@users.noreply.github.com>
Date: Mon, 26 Aug 2024 15:11:41 -0400
Subject: 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>
---
 source/slang/slang-type-layout.cpp | 38 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 36 insertions(+), 2 deletions(-)

(limited to 'source/slang/slang-type-layout.cpp')

diff --git a/source/slang/slang-type-layout.cpp b/source/slang/slang-type-layout.cpp
index f5fbfafdf..7d6d047d3 100644
--- a/source/slang/slang-type-layout.cpp
+++ b/source/slang/slang-type-layout.cpp
@@ -400,6 +400,12 @@ struct HLSLConstantBufferLayoutRulesImpl : DefaultLayoutRulesImpl
     }
 };
 
+/// GLSL fvk-use-dx-layout for `ShaderResource`
+struct FXCShaderResourceLayoutRulesImpl : DefaultLayoutRulesImpl
+{
+    // Currently this FXC layout is equal to how we compute 'DefaultLayoutRulesImpl'
+};
+
 /* CPU layout requires that all sizes are a multiple of alignment.
 */
 struct CPULayoutRulesImpl : DefaultLayoutRulesImpl
@@ -894,6 +900,7 @@ struct CUDARayTracingLayoutRulesImpl : DefaultVaryingLayoutRulesImpl
 DefaultLayoutRulesImpl kDefaultLayoutRulesImpl;
 Std140LayoutRulesImpl kStd140LayoutRulesImpl;
 Std430LayoutRulesImpl kStd430LayoutRulesImpl;
+FXCShaderResourceLayoutRulesImpl kFXCShaderResourceLayoutRulesImpl;
 HLSLConstantBufferLayoutRulesImpl kHLSLConstantBufferLayoutRulesImpl;
 HLSLStructuredBufferLayoutRulesImpl kHLSLStructuredBufferLayoutRulesImpl;
 
@@ -1206,6 +1213,18 @@ LayoutRulesImpl kScalarLayoutRulesImpl_ = {
     &kGLSLObjectLayoutRulesImpl,
 };
 
+LayoutRulesImpl kFXCShaderResourceLayoutRulesFamilyImpl = {
+    &kGLSLLayoutRulesFamilyImpl,
+    &kFXCShaderResourceLayoutRulesImpl,
+    &kGLSLObjectLayoutRulesImpl,
+};
+
+LayoutRulesImpl kFXCConstantBufferLayoutRulesFamilyImpl = {
+    &kGLSLLayoutRulesFamilyImpl,
+    &kHLSLConstantBufferLayoutRulesImpl,
+    &kGLSLObjectLayoutRulesImpl,
+};
+
 LayoutRulesImpl kGLSLAnyValueLayoutRulesImpl_ = {
     &kGLSLLayoutRulesFamilyImpl,
     &kDefaultLayoutRulesImpl,
@@ -1300,6 +1319,9 @@ LayoutRulesImpl* GLSLLayoutRulesFamilyImpl::getConstantBufferRules(CompilerOptio
 {
     if (compilerOptions.shouldUseScalarLayout())
         return &kScalarLayoutRulesImpl_;
+    else if (compilerOptions.shouldUseDXLayout())
+        return &kFXCConstantBufferLayoutRulesFamilyImpl;
+
     return &kStd140LayoutRulesImpl_;
 }
 
@@ -1307,6 +1329,9 @@ LayoutRulesImpl* GLSLLayoutRulesFamilyImpl::getParameterBlockRules(CompilerOptio
 {
     if (compilerOptions.shouldUseScalarLayout())
         return &kScalarLayoutRulesImpl_;
+    else if (compilerOptions.shouldUseDXLayout())
+        return &kFXCConstantBufferLayoutRulesFamilyImpl;
+
     return &kStd140LayoutRulesImpl_;
 }
 
@@ -1324,6 +1349,9 @@ LayoutRulesImpl* GLSLLayoutRulesFamilyImpl::getTextureBufferRules(CompilerOption
 {
     if (compilerOptions.shouldUseScalarLayout())
         return &kScalarLayoutRulesImpl_;
+    else if (compilerOptions.shouldUseDXLayout())
+        return &kFXCConstantBufferLayoutRulesFamilyImpl;
+
     return &kStd430LayoutRulesImpl_;
 
 }
@@ -1347,6 +1375,9 @@ LayoutRulesImpl* GLSLLayoutRulesFamilyImpl::getShaderStorageBufferRules(Compiler
 {
     if (compilerOptions.shouldUseScalarLayout())
         return &kScalarLayoutRulesImpl_;
+    else if (compilerOptions.shouldUseDXLayout())
+        return &kFXCShaderResourceLayoutRulesFamilyImpl;
+
     return &kStd430LayoutRulesImpl_;
 }
 
@@ -1365,10 +1396,13 @@ LayoutRulesImpl* GLSLLayoutRulesFamilyImpl::getHitAttributesParameterRules()
     return &kGLSLHitAttributesParameterLayoutRulesImpl_;
 }
 
-LayoutRulesImpl* GLSLLayoutRulesFamilyImpl::getStructuredBufferRules(CompilerOptionSet& options)
+LayoutRulesImpl* GLSLLayoutRulesFamilyImpl::getStructuredBufferRules(CompilerOptionSet& compilerOptions)
 {
-    if (options.shouldUseScalarLayout())
+    if (compilerOptions.shouldUseScalarLayout())
         return &kScalarLayoutRulesImpl_;
+    else if (compilerOptions.shouldUseDXLayout())
+        return &kFXCShaderResourceLayoutRulesFamilyImpl;
+
     return &kGLSLStructuredBufferLayoutRulesImpl_;
 }
 
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