From 7e2bc8e06f61d554bae9bbebc1db0302eb3f1d8a Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Fri, 26 Jul 2024 19:42:15 -0700
Subject: Allow passing sized array to unsized array parameter. (#4744)

---
 source/slang/slang-ir-specialize-arrays.cpp | 47 +++++++++++++++++++++++++++--
 1 file changed, 45 insertions(+), 2 deletions(-)

(limited to 'source/slang/slang-ir-specialize-arrays.cpp')

diff --git a/source/slang/slang-ir-specialize-arrays.cpp b/source/slang/slang-ir-specialize-arrays.cpp
index 3f42fb4b0..9bc0042db 100644
--- a/source/slang/slang-ir-specialize-arrays.cpp
+++ b/source/slang/slang-ir-specialize-arrays.cpp
@@ -13,8 +13,11 @@ struct ArrayParameterSpecializationCondition : FunctionCallSpecializeCondition
     // This pass is intended to specialize functions
     // with struct parameters that has array fields
     // to avoid performance problems for GLSL targets.
-
     // Returns true if `type` is an `IRStructType` with array-typed fields.
+    // It will also specialize functions with unsized array parameters into
+    // sized arrays, if the function is called with an argument that has a
+    // sized array type.
+    //
     bool isStructTypeWithArray(IRType* type)
     {
         if (auto structType = as<IRStructType>(type))
@@ -38,8 +41,47 @@ struct ArrayParameterSpecializationCondition : FunctionCallSpecializeCondition
     bool doesParamWantSpecialization(IRParam* param, IRInst* arg)
     {
         SLANG_UNUSED(arg);
-        return isStructTypeWithArray(param->getDataType());
+        if (isKhronosTarget(codeGenContext->getTargetReq()))
+            return isStructTypeWithArray(param->getDataType());
+        return false;
     }
+
+    bool doesParamTypeWantSpecialization(IRParam* param, IRInst* arg)
+    {
+        auto paramType = param->getDataType();
+        auto argType = arg->getDataType();
+        if (auto outTypeBase = as<IROutTypeBase>(paramType))
+        {
+            paramType = outTypeBase->getValueType();
+            SLANG_ASSERT(as<IRPtrTypeBase>(argType));
+            argType = as<IRPtrTypeBase>(argType)->getValueType();
+        }
+        else if (auto refType = as<IRRefType>(paramType))
+        {
+            paramType = refType->getValueType();
+            SLANG_ASSERT(as<IRPtrTypeBase>(argType));
+            argType = as<IRPtrTypeBase>(argType)->getValueType();
+        }
+        else if (auto constRefType = as<IRConstRefType>(paramType))
+        {
+            paramType = constRefType->getValueType();
+            SLANG_ASSERT(as<IRPtrTypeBase>(argType));
+            argType = as<IRPtrTypeBase>(argType)->getValueType();
+        }
+        auto arrayType = as<IRUnsizedArrayType>(paramType);
+        if (!arrayType)
+            return false;
+        auto argArrayType = as<IRArrayType>(argType);
+        if (!argArrayType)
+            return false;
+        if (as<IRIntLit>(argArrayType->getElementCount()))
+        {
+            return true;
+        }
+        return false;
+    }
+
+    CodeGenContext* codeGenContext = nullptr;
 };
 
 void specializeArrayParameters(
@@ -47,6 +89,7 @@ void specializeArrayParameters(
     IRModule*       module)
 {
     ArrayParameterSpecializationCondition condition;
+    condition.codeGenContext = codeGenContext;
     specializeFunctionCalls(codeGenContext, module, &condition);
 }
 
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