Hoist resource variables using a global initializer function correctly

Fixes: shader-slang#4874
Hoist resource variables using a global initializer function in such a way that the initializer function is passed into every entry-point opposed to emitting a local-variable asignment in global scope.

source/slang/slang-ir-legalize-types.cpp

@@ -343,8 +343,20 @@ struct LegalCallBuilder
                 // result type of the function, so we know that
                 // the legalization funciton/call will use a `void`
                 // result type.
-                //
-                _emitCall(m_context->builder->getVoidType());
+
+                // If our call is in global scope (initializer) we should
+                // hoist the call into the start of every entry-point 
+                if (!m_context->builder->getInsertLoc().getInst()->getParent()
+                    || m_context->builder->getInsertLoc().getInst()->getParent()->getOp() == kIROp_Module)
+                {
+                    for (auto i : m_context->getEntryPoints())
+                    {
+                        m_context->builder->setInsertBefore(i->getFirstOrdinaryInst());
+                        _emitCall(m_context->builder->getVoidType());
+                    }
+                }
+                else
+                    _emitCall(m_context->builder->getVoidType());
                 return resultVal;
             }
             break;
@@ -370,11 +382,19 @@ struct LegalCallBuilder
                 auto simpleType = resultType.getSimple();
                 auto builder = m_context->builder;
 
-                // Recall that a local variable in our IR represents a *pointer*
+                // Recall that a variable in our IR represents a *pointer*
                 // to storage of the appropriate type.
                 //
-                auto varPtr = builder->emitVar(simpleType);
-
+                IRInst* varPtr = nullptr;
+                if (m_call->parent->getOp() == kIROp_Module)
+                {
+                    // If we were going to emit an IRVar in global scope, emit a GlobalVar instead 
+                    varPtr = builder->createGlobalVar(simpleType);
+                }
+                else
+                {
+                    varPtr = builder->emitVar(simpleType);
+                }
                 // We need to pass that pointer as an argument to our new
                 // `call` instruction, so that it can receive the value
                 // written by the callee.

source/slang/slang-legalize-types.h

@@ -605,6 +605,21 @@ struct IRTypeLegalizationContext
     TargetProgram* targetProgram;
     IRBuilder builderStorage;
 
+    List<IRFunc*> entryPoints;
+    List<IRFunc*>& getEntryPoints()
+    {
+        if (entryPoints.getCount() == 0)
+        {
+            for (auto i : module->getGlobalInsts())
+            {
+                if (auto func = as<IRFunc>(i))
+                    if (i->findDecoration<IREntryPointDecoration>())
+                        entryPoints.add(func);
+            }
+        }
+        return entryPoints;
+    }
+
     IRTypeLegalizationContext(
         TargetProgram* target,
         IRModule* inModule);

tests/compute/type-legalize-global-with-init-function.slang

@@ -0,0 +1,48 @@
+// type-legalize-global-with-init.slang
+//
+// Confirm that type legalization can handle a global constant
+// with a resource type or a type that recursively contains
+// resources.
+//
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=BUF): -shaderobj
+//
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<uint> outputBuffer;
+
+//TEST_INPUT:ubuffer(data=[1 2 3 4 5 6 7 8], stride=4):name=inputBuffer
+RWStructuredBuffer<uint> inputBuffer;
+
+static const RWStructuredBuffer<uint> gBuffer = inputBuffer;
+
+struct Stuff
+{
+    __init(RWStructuredBuffer<uint> inA, RWStructuredBuffer<uint> inB)
+    {
+        a = inA;
+        b = inB;
+    }
+    RWStructuredBuffer<uint> a;
+    RWStructuredBuffer<uint> b;
+}
+
+static const Stuff gStuff = Stuff( inputBuffer, inputBuffer );
+
+uint test(uint x)
+{
+    return gBuffer[x]
+        + gStuff.a[x + 1] * 16
+        + gStuff.b[x + 2] * 256;
+}
+
+[numthreads(4, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    let tid = dispatchThreadID.x;
+    let inVal = tid;
+    let outVal = test(inVal);
+    outputBuffer[tid] = outVal;
+}
+//BUF: 321
+//BUF: 432
+//BUF: 543
+//BUF: 654

tests/compute/type-legalize-global-with-init.slang

@@ -4,7 +4,7 @@
 // with a resource type or a type that recursively contains
 // resources.
 //
-//TEST(compute):COMPARE_COMPUTE: -shaderobj
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=BUF): -shaderobj
 //
 //TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=outputBuffer
 RWStructuredBuffer<uint> outputBuffer;
@@ -37,3 +37,8 @@ void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
     let outVal = test(inVal);
     outputBuffer[tid] = outVal;
 }
+//BUF: 321
+//BUF: 432
+//BUF: 543
+//BUF: 654
+