Support for [[vk::push_constant]] (#629)

* Support for attributed [[vk::push_constant]] and [[push_constant]]. Can also use layout(push_constant).

* Fix test so matches the expected output.

* Add expected output to binding-push-constant-gl.hlsl

* Trivial change to force travis rebuild to test the gcc linux build really has a problem.

7 files changed, 62 insertions, 24 deletions

diff --git a/source/slang/check.cpp b/source/slang/check.cpp
index c5ebf7f30..95a958495 100644
--- a/source/slang/check.cpp
+++ b/source/slang/check.cpp
@@ -1959,6 +1959,11 @@ namespace Slang
                         getSink()->diagnose(attr, Diagnostics::expectedSingleIntArg, attr->name);
                     }
                 }
+                else if (attr.As<PushConstantAttribute>())
+                {
+                    // Has no args
+                    SLANG_ASSERT(attr->args.Count() == 0);
+                }
                 else 
                 {
                     if(attr->args.Count() == 0)
diff --git a/source/slang/core.meta.slang b/source/slang/core.meta.slang
index 9da424fba..31da44f3c 100644
--- a/source/slang/core.meta.slang
+++ b/source/slang/core.meta.slang
@@ -1122,6 +1122,11 @@ attribute_syntax [vk_binding(binding: int, set: int = 0)]			: GLSLBindingAttribu
 __attributeTarget(DeclBase)
 attribute_syntax [gl_binding(binding: int, set: int = 0)]			: GLSLBindingAttribute;
 
+__attributeTarget(DeclBase)
+attribute_syntax [vk_push_constant]									: PushConstantAttribute;
+__attributeTarget(DeclBase)
+attribute_syntax [push_constant]									: PushConstantAttribute;
+
 // Statement Attributes
 
 __attributeTarget(LoopStmt)
diff --git a/source/slang/core.meta.slang.h b/source/slang/core.meta.slang.h
index 0f69d0b5b..12c76d213 100644
--- a/source/slang/core.meta.slang.h
+++ b/source/slang/core.meta.slang.h
@@ -1140,6 +1140,11 @@ SLANG_RAW("\n")
 SLANG_RAW("__attributeTarget(DeclBase)\n")
 SLANG_RAW("attribute_syntax [gl_binding(binding: int, set: int = 0)]\t\t\t: GLSLBindingAttribute;\n")
 SLANG_RAW("\n")
+SLANG_RAW("__attributeTarget(DeclBase)\n")
+SLANG_RAW("attribute_syntax [vk_push_constant]\t\t\t\t\t\t\t\t\t: PushConstantAttribute;\n")
+SLANG_RAW("__attributeTarget(DeclBase)\n")
+SLANG_RAW("attribute_syntax [push_constant]\t\t\t\t\t\t\t\t\t: PushConstantAttribute;\n")
+SLANG_RAW("\n")
 SLANG_RAW("// Statement Attributes\n")
 SLANG_RAW("\n")
 SLANG_RAW("__attributeTarget(LoopStmt)\n")
diff --git a/source/slang/emit.cpp b/source/slang/emit.cpp
index 8d31ca064..1d121d69b 100644
--- a/source/slang/emit.cpp
+++ b/source/slang/emit.cpp
@@ -5394,6 +5394,7 @@ struct EmitVisitor
         }
 
         emitGLSLLayoutQualifier(LayoutResourceKind::DescriptorTableSlot, &containerChain);
+        emitGLSLLayoutQualifier(LayoutResourceKind::PushConstantBuffer, &containerChain);
 
         if(as<IRGLSLShaderStorageBufferType>(type))
         {
diff --git a/source/slang/modifier-defs.h b/source/slang/modifier-defs.h
index 70c26568d..d53f8bc6c 100644
--- a/source/slang/modifier-defs.h
+++ b/source/slang/modifier-defs.h
@@ -129,7 +129,6 @@ SIMPLE_SYNTAX_CLASS(GLSLUnparsedLayoutModifier   , GLSLLayoutModifier)
 // Specific cases for known GLSL `layout` modifiers that we need to work with
 SIMPLE_SYNTAX_CLASS(GLSLConstantIDLayoutModifier , GLSLParsedLayoutModifier)
 SIMPLE_SYNTAX_CLASS(GLSLLocationLayoutModifier   , GLSLParsedLayoutModifier)
-SIMPLE_SYNTAX_CLASS(GLSLPushConstantLayoutModifier, GLSLParsedLayoutModifier)
 
 SIMPLE_SYNTAX_CLASS(GLSLLocalSizeLayoutModifier,    GLSLUnparsedLayoutModifier)
 SIMPLE_SYNTAX_CLASS(GLSLLocalSizeXLayoutModifier,    GLSLLocalSizeLayoutModifier)
@@ -328,6 +327,9 @@ SIMPLE_SYNTAX_CLASS(FlattenAttribute, Attribute)            // `[flatten]`
 SIMPLE_SYNTAX_CLASS(ForceCaseAttribute, Attribute)          // `[forcecase]`
 SIMPLE_SYNTAX_CLASS(CallAttribute, Attribute)               // `[call]`
 
+// [[vk_push_constant]] [[push_constant]]
+SIMPLE_SYNTAX_CLASS(PushConstantAttribute, Attribute)
+
 // [[vk_binding]]
 SYNTAX_CLASS(GLSLBindingAttribute, Attribute)
     FIELD(int32_t, binding = 0)
diff --git a/source/slang/parameter-binding.cpp b/source/slang/parameter-binding.cpp
index ced8d7af2..40491c4df 100644
--- a/source/slang/parameter-binding.cpp
+++ b/source/slang/parameter-binding.cpp
@@ -977,7 +977,7 @@ getTypeLayoutForGlobalShaderParameter_GLSL(
 
     // We want to check for a constant-buffer type with a `push_constant` layout
     // qualifier before we move on to anything else.
-    if( varDecl->HasModifier<GLSLPushConstantLayoutModifier>() && type->As<ConstantBufferType>() )
+    if( varDecl->HasModifier<PushConstantAttribute>() && type->As<ConstantBufferType>() )
     {
         return CreateTypeLayout(
             layoutContext.with(rules->getPushConstantBufferRules()),
@@ -1043,6 +1043,15 @@ getTypeLayoutForGlobalShaderParameter_HLSL(
     auto rules = layoutContext.getRulesFamily();
     auto type = varDecl->getType();
 
+    // We want to check for a constant-buffer type with a `push_constant` layout
+    // qualifier before we move on to anything else.
+    if (varDecl->HasModifier<PushConstantAttribute>() && type->As<ConstantBufferType>())
+    {
+        return CreateTypeLayout(
+            layoutContext.with(rules->getPushConstantBufferRules()),
+            type);
+    }
+
     // HLSL `static` modifier indicates "thread local"
     if(varDecl->HasModifier<HLSLStaticModifier>())
         return nullptr;
diff --git a/source/slang/parser.cpp b/source/slang/parser.cpp
index 62fed75cc..e3982aee4 100644
--- a/source/slang/parser.cpp
+++ b/source/slang/parser.cpp
@@ -4511,35 +4511,46 @@ namespace Slang
             }
             else
             {
-                RefPtr<GLSLLayoutModifier> modifier;
-
-                // TODO: better handling of this choice (e.g., lookup in scope)
-                if(0) {}
-            #define CASE(KEYWORD, CLASS) \
-                else if(getText(nameAndLoc.name) == #KEYWORD) modifier = new CLASS()
+                if (nameText == "push_constant")
+                {
+                    RefPtr<PushConstantAttribute> modifier(new PushConstantAttribute);
 
-                CASE(constant_id,   GLSLConstantIDLayoutModifier);
-                CASE(location,      GLSLLocationLayoutModifier);
-                CASE(push_constant, GLSLPushConstantLayoutModifier);
-                CASE(local_size_x,  GLSLLocalSizeXLayoutModifier);
-                CASE(local_size_y,  GLSLLocalSizeYLayoutModifier);
-                CASE(local_size_z,  GLSLLocalSizeZLayoutModifier);
+                    modifier->name = nameAndLoc.name;
+                    modifier->loc = nameAndLoc.loc;
 
-            #undef CASE
+                    listBuilder.add(modifier);
+                }
                 else
                 {
-                    modifier = new GLSLUnparsedLayoutModifier();
-                }
+                    RefPtr<GLSLLayoutModifier> modifier;
 
-                modifier->name = nameAndLoc.name;
-                modifier->loc = nameAndLoc.loc;
+                    // TODO: better handling of this choice (e.g., lookup in scope)
+                    if(0) {}
+                #define CASE(KEYWORD, CLASS) \
+                    else if(nameText == #KEYWORD) modifier = new CLASS()
 
-                if(AdvanceIf(parser, TokenType::OpAssign))
-                {
-                    modifier->valToken = parser->ReadToken(TokenType::IntegerLiteral);
-                }
+                    CASE(constant_id,   GLSLConstantIDLayoutModifier);
+                    CASE(location,      GLSLLocationLayoutModifier);
+                    CASE(local_size_x,  GLSLLocalSizeXLayoutModifier);
+                    CASE(local_size_y,  GLSLLocalSizeYLayoutModifier);
+                    CASE(local_size_z,  GLSLLocalSizeZLayoutModifier);
 
-                listBuilder.add(modifier);
+                #undef CASE
+                    else
+                    {
+                        modifier = new GLSLUnparsedLayoutModifier();
+                    }
+
+                    modifier->name = nameAndLoc.name;
+                    modifier->loc = nameAndLoc.loc;
+
+                    if(AdvanceIf(parser, TokenType::OpAssign))
+                    {
+                        modifier->valToken = parser->ReadToken(TokenType::IntegerLiteral);
+                    }
+
+                    listBuilder.add(modifier);
+                }
             }
 
             if (AdvanceIf(parser, TokenType::RParent))