From fd09feaaa19c1ae3441dd687bced1b12ff7c768e Mon Sep 17 00:00:00 2001
From: kaizhangNV <149626564+kaizhangNV@users.noreply.github.com>
Date: Wed, 9 Apr 2025 16:24:17 -0500
Subject: void field rework (#6739)

* void field rework

* move void cleanup pass earlier
---
 source/slang/slang-emit.cpp              |  3 ++-
 source/slang/slang-ir-cleanup-void.cpp   | 24 ------------------------
 source/slang/slang-ir-legalize-types.cpp |  2 ++
 source/slang/slang-ir-peephole.cpp       |  6 ++++++
 4 files changed, 10 insertions(+), 25 deletions(-)

diff --git a/source/slang/slang-emit.cpp b/source/slang/slang-emit.cpp
index 4eb4719f0..9cfa7dcae 100644
--- a/source/slang/slang-emit.cpp
+++ b/source/slang/slang-emit.cpp
@@ -1716,6 +1716,8 @@ Result linkAndOptimizeIR(
     //
     eliminateDeadCode(irModule, deadCodeEliminationOptions);
 
+    cleanUpVoidType(irModule);
+
     if (isKhronosTarget(targetRequest))
     {
         // As a fallback, if the above specialization steps failed to remove resource type
@@ -1728,7 +1730,6 @@ Result linkAndOptimizeIR(
 #endif
     validateIRModuleIfEnabled(codeGenContext, irModule);
 
-    cleanUpVoidType(irModule);
 
     // Lower the `getRegisterIndex` and `getRegisterSpace` intrinsics.
     //
diff --git a/source/slang/slang-ir-cleanup-void.cpp b/source/slang/slang-ir-cleanup-void.cpp
index 84532d0ec..3a776fc4f 100644
--- a/source/slang/slang-ir-cleanup-void.cpp
+++ b/source/slang/slang-ir-cleanup-void.cpp
@@ -122,8 +122,6 @@ struct CleanUpVoidContext
         case kIROp_StructType:
             {
                 List<IRInst*> toRemove;
-                UInt fieldCount = 0;
-                ShortList<UInt> voidFieldIndex;
                 for (auto child : inst->getChildren())
                 {
                     if (auto field = as<IRStructField>(child))
@@ -131,33 +129,11 @@ struct CleanUpVoidContext
                         if (field->getFieldType()->getOp() == kIROp_VoidType)
                         {
                             toRemove.add(field);
-                            voidFieldIndex.add(fieldCount);
                         }
                     }
-                    fieldCount++;
                 }
                 for (auto ii : toRemove)
                     ii->removeAndDeallocate();
-
-                // Once we remove the void fields in the struct, we also need update the make_struct
-                // call sites to remove the arguments corresponding to the void fields.
-                if (inst->hasUses() && voidFieldIndex.getCount())
-                {
-                    UInt currentFieldCount = fieldCount - toRemove.getCount();
-                    for (auto use = inst->firstUse; use; use = use->nextUse)
-                    {
-                        if (auto makeStructInst = as<IRMakeStruct>(use->user))
-                        {
-                            if (makeStructInst->getOperandCount() != currentFieldCount)
-                            {
-                                for (Int i = 0; i < voidFieldIndex.getCount(); i++)
-                                {
-                                    makeStructInst->removeOperand(voidFieldIndex[i]);
-                                }
-                            }
-                        }
-                    }
-                }
             }
             break;
         default:
diff --git a/source/slang/slang-ir-legalize-types.cpp b/source/slang/slang-ir-legalize-types.cpp
index 837193abc..af29d1998 100644
--- a/source/slang/slang-ir-legalize-types.cpp
+++ b/source/slang/slang-ir-legalize-types.cpp
@@ -1962,6 +1962,8 @@ static LegalVal coerceToLegalType(IRTypeLegalizationContext* context, LegalType
             ShortList<IRInst*> fields;
             for (auto field : structType->getFields())
             {
+                if (as<IRVoidType>(field->getFieldType()))
+                    continue;
                 auto fieldVal = coerceToLegalType(
                     context,
                     LegalType::simple(field->getFieldType()),
diff --git a/source/slang/slang-ir-peephole.cpp b/source/slang/slang-ir-peephole.cpp
index e29fdf975..28e98fdb6 100644
--- a/source/slang/slang-ir-peephole.cpp
+++ b/source/slang/slang-ir-peephole.cpp
@@ -402,6 +402,12 @@ struct PeepholeContext : InstPassBase
                     Index i = 0;
                     for (auto sfield : structType->getFields())
                     {
+                        // skip the void field
+                        if (as<IRVoidType>(sfield->getFieldType()))
+                        {
+                            continue;
+                        }
+
                         if (sfield->getKey() == field)
                         {
                             fieldIndex = i;
-- 
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