From 16ac0efa3e1e834e3b12af8ac34cf47a6418bb34 Mon Sep 17 00:00:00 2001
From: Darren Wihandi <65404740+fairywreath@users.noreply.github.com>
Date: Fri, 21 Mar 2025 10:31:07 -0400
Subject: Apply pixel interlock execution mode to entry-point functions only
 (#6661)

Co-authored-by: Ellie Hermaszewska <ellieh@nvidia.com>
---
 source/slang/slang-emit-spirv.cpp | 64 ++++++++++++++++++++++-----------------
 1 file changed, 36 insertions(+), 28 deletions(-)

(limited to 'source')

diff --git a/source/slang/slang-emit-spirv.cpp b/source/slang/slang-emit-spirv.cpp
index 266f3b7e9..8ecbe1bc7 100644
--- a/source/slang/slang-emit-spirv.cpp
+++ b/source/slang/slang-emit-spirv.cpp
@@ -3640,35 +3640,20 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
             }
 
         case kIROp_RequireMaximallyReconverges:
-            if (auto entryPointsUsingInst =
-                    getReferencingEntryPoints(m_referencingEntryPoints, getParentFunc(inst)))
-            {
-                ensureExtensionDeclaration(UnownedStringSlice("SPV_KHR_maximal_reconvergence"));
-                for (IRFunc* entryPoint : *entryPointsUsingInst)
-                {
-                    requireSPIRVExecutionMode(
-                        nullptr,
-                        getIRInstSpvID(entryPoint),
-                        SpvExecutionModeMaximallyReconvergesKHR);
-                }
-            }
+            ensureExtensionDeclaration(UnownedStringSlice("SPV_KHR_maximal_reconvergence"));
+            requireSPIRVExecutionModeOnReferencingEntryPoints(
+                nullptr,
+                getParentFunc(inst),
+                SpvExecutionModeMaximallyReconvergesKHR);
             break;
         case kIROp_RequireQuadDerivatives:
-            if (auto entryPointsUsingInst =
-                    getReferencingEntryPoints(m_referencingEntryPoints, getParentFunc(inst)))
-            {
-                ensureExtensionDeclaration(UnownedStringSlice("SPV_KHR_quad_control"));
-                requireSPIRVCapability(SpvCapabilityQuadControlKHR);
-                for (IRFunc* entryPoint : *entryPointsUsingInst)
-                {
-                    requireSPIRVExecutionMode(
-                        nullptr,
-                        getIRInstSpvID(entryPoint),
-                        SpvExecutionModeQuadDerivativesKHR);
-                }
-            }
+            ensureExtensionDeclaration(UnownedStringSlice("SPV_KHR_quad_control"));
+            requireSPIRVCapability(SpvCapabilityQuadControlKHR);
+            requireSPIRVExecutionModeOnReferencingEntryPoints(
+                nullptr,
+                getParentFunc(inst),
+                SpvExecutionModeQuadDerivativesKHR);
             break;
-
         case kIROp_Return:
             if (as<IRReturn>(inst)->getVal()->getOp() == kIROp_VoidLit)
                 result = emitOpReturn(parent, inst);
@@ -3691,9 +3676,9 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
         case kIROp_BeginFragmentShaderInterlock:
             ensureExtensionDeclaration(UnownedStringSlice("SPV_EXT_fragment_shader_interlock"));
             requireSPIRVCapability(SpvCapabilityFragmentShaderPixelInterlockEXT);
-            requireSPIRVExecutionMode(
+            requireSPIRVExecutionModeOnReferencingEntryPoints(
                 nullptr,
-                getIRInstSpvID(getParentFunc(inst)),
+                getParentFunc(inst),
                 SpvExecutionModePixelInterlockOrderedEXT);
             result = emitOpBeginInvocationInterlockEXT(parent, inst);
             break;
@@ -8280,6 +8265,29 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
         }
     }
 
+    // Applies execution mode to entry points that reference `childFunc`.
+    template<typename... Operands>
+    void requireSPIRVExecutionModeOnReferencingEntryPoints(
+        IRInst* parentInst,
+        IRFunc* childFunc,
+        SpvExecutionMode executionMode,
+        const Operands&... ops)
+    {
+
+        if (auto entryPointsUsingInst =
+                getReferencingEntryPoints(m_referencingEntryPoints, childFunc))
+        {
+            for (IRFunc* entryPoint : *entryPointsUsingInst)
+            {
+                requireSPIRVExecutionMode(
+                    parentInst,
+                    getIRInstSpvID(entryPoint),
+                    executionMode,
+                    ops...);
+            }
+        }
+    }
+
     SPIRVEmitContext(IRModule* module, TargetProgram* program, DiagnosticSink* sink)
         : SPIRVEmitSharedContext(module, program, sink), m_irModule(module), m_memoryArena(2048)
     {
-- 
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