From fa917fedc89287778eef65a62413ff09d1065d97 Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Tue, 19 Nov 2024 09:03:48 -0800
Subject: Fix specialization constant miscompile in glsl mode. (#5568)

Co-authored-by: Ellie Hermaszewska <ellieh@nvidia.com>
---
 source/slang/slang-check-decl.cpp         | 14 +++++++++++++-
 tests/spirv/specialization-constant.slang |  2 ++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/source/slang/slang-check-decl.cpp b/source/slang/slang-check-decl.cpp
index fb27614d0..07d5dd1fa 100644
--- a/source/slang/slang-check-decl.cpp
+++ b/source/slang/slang-check-decl.cpp
@@ -1709,6 +1709,18 @@ void SemanticsDeclHeaderVisitor::maybeApplyLayoutModifier(VarDeclBase* varDecl)
     }
 }
 
+bool isSpecializationConstant(VarDeclBase* varDecl)
+{
+    for (auto modifier : varDecl->modifiers)
+    {
+        if (as<SpecializationConstantAttribute>(modifier))
+            return true;
+        if (as<VkConstantIdAttribute>(modifier))
+            return true;
+    }
+    return false;
+}
+
 void SemanticsDeclHeaderVisitor::checkVarDeclCommon(VarDeclBase* varDecl)
 {
     // A variable that didn't have an explicit type written must
@@ -1943,7 +1955,7 @@ void SemanticsDeclHeaderVisitor::checkVarDeclCommon(VarDeclBase* varDecl)
             // without any `uniform` modifiers as true global variables by default.
             if (!varDecl->findModifier<HLSLUniformModifier>() &&
                 !varDecl->findModifier<InModifier>() && !varDecl->findModifier<OutModifier>() &&
-                !varDecl->findModifier<GLSLBufferModifier>())
+                !varDecl->findModifier<GLSLBufferModifier>() && !isSpecializationConstant(varDecl))
             {
                 if (!isUniformParameterType(varDecl->type))
                 {
diff --git a/tests/spirv/specialization-constant.slang b/tests/spirv/specialization-constant.slang
index 63141d25e..dbf315926 100644
--- a/tests/spirv/specialization-constant.slang
+++ b/tests/spirv/specialization-constant.slang
@@ -1,4 +1,6 @@
+//TEST:SIMPLE(filecheck=GLSL): -target glsl -allow-glsl
 //TEST:SIMPLE(filecheck=GLSL): -target glsl
+//TEST:SIMPLE(filecheck=CHECK): -target spirv -allow-glsl
 //TEST:SIMPLE(filecheck=CHECK): -target spirv
 
 // CHECK-DAG: OpDecorate %[[C0:[0-9A-Za-z_]+]] SpecId 0
-- 
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