Rework limit large kernels from LICM

Changes pass to a function pass and adds additional criteria for what is
considered a "large" kernel.

Author: pmkippes

IGC/Compiler/CISACodeGen/ShaderCodeGen.cpp

@@ -1,6 +1,6 @@
 /*========================== begin_copyright_notice ============================
 
-Copyright (C) 2017-2022 Intel Corporation
+Copyright (C) 2017-2024 Intel Corporation
 
 SPDX-License-Identifier: MIT
 
@@ -502,7 +502,7 @@ void AddLegalizationPasses(CodeGenContext& ctx, IGCPassManager& mpm, PSSignature
 
         if (IGC_IS_FLAG_ENABLED(allowLICM) && ctx.m_retryManager.AllowLICM())
         {
-            mpm.add(createDisableLICMForSpecificLoops());
+            mpm.add(createSpecialCasesDisableLICM());
             mpm.add(llvm::createLICMPass());
         }
         mpm.add(llvm::createLoopSimplifyPass());
@@ -891,7 +891,7 @@ void AddLegalizationPasses(CodeGenContext& ctx, IGCPassManager& mpm, PSSignature
         }
         if (!fastCompile && !highAllocaPressure && !isPotentialHPCKernel && IGC_IS_FLAG_ENABLED(allowLICM) && ctx.m_retryManager.AllowLICM())
         {
-            mpm.add(createDisableLICMForSpecificLoops());
+            mpm.add(createSpecialCasesDisableLICM());
             mpm.add(createLICMPass());
             mpm.add(llvm::createEarlyCSEPass());
         }
@@ -1466,7 +1466,7 @@ void OptimizeIR(CodeGenContext* const pContext)
 
                 if (IGC_IS_FLAG_ENABLED(allowLICM) && pContext->m_retryManager.AllowLICM())
                 {
-                    mpm.add(createDisableLICMForSpecificLoops());
+                    mpm.add(createSpecialCasesDisableLICM());
                     int licmTh = IGC_GET_FLAG_VALUE(LICMStatThreshold);
                     mpm.add(new InstrStatistic(pContext, LICM_STAT, InstrStatStage::BEGIN, licmTh));
                     mpm.add(llvm::createLICMPass());
@@ -1523,7 +1523,7 @@ void OptimizeIR(CodeGenContext* const pContext)
 
                 if (IGC_IS_FLAG_ENABLED(allowLICM) && pContext->m_retryManager.AllowLICM())
                 {
-                    mpm.add(createDisableLICMForSpecificLoops());
+                    mpm.add(createSpecialCasesDisableLICM());
                     mpm.add(llvm::createLICMPass());
                 }
 

IGC/Compiler/CustomLoopOpt.cpp

@@ -1,6 +1,6 @@
 /*========================== begin_copyright_notice ============================
 
-Copyright (C) 2017-2021 Intel Corporation
+Copyright (C) 2017-2024 Intel Corporation
 
 SPDX-License-Identifier: MIT
 
@@ -1160,70 +1160,96 @@ namespace IGC
     }
 }
 
-class DisableLICMForSpecificLoops : public llvm::LoopPass
+// This pass disables LICM optimization by adding llvm.licm.disable
+// - when Loop depends on SIMD Lane Id and operates on local memory or
+// - when the loops are part of a large function and the number of loops
+//   is sizable where a potential stack overflow from memory SSA updater
+//   could occur.
+
+class SpecialCasesDisableLICM : public llvm::FunctionPass
 {
 public:
     static char ID;
 
-    DisableLICMForSpecificLoops();
+    SpecialCasesDisableLICM();
 
     void getAnalysisUsage(llvm::AnalysisUsage& AU) const
     {
         AU.addPreservedID(LCSSAID);
+        AU.addRequired<llvm::LoopInfoWrapperPass>();
     }
 
-    bool runOnLoop(Loop* L, LPPassManager& LPM);
+    bool runOnFunction(Function& F);
     bool LoopHasLoadFromLocalAddressSpace(const Loop& L);
     bool LoopDependsOnSIMDLaneId(const Loop& L);
     bool AddLICMDisableMedatadaToSpecificLoop(Loop& L);
 
     llvm::StringRef getPassName() const
     {
-        return "IGC disable LICM for specific loops";
+        return "IGC special cases disable LICM";
     }
 };
+
 #undef PASS_FLAG
 #undef PASS_DESC
 #undef PASS_CFG_ONLY
 #undef PASS_ANALYSIS
-#define PASS_FLAG     "igc-disable-licm-for-specific-loops"
-#define PASS_DESC     "IGC disable LICM for specific loops"
+#define PASS_FLAG     "igc-special-cases-disable-licm"
+#define PASS_DESC     "IGC special cases disable LICM"
 #define PASS_CFG_ONLY false
 #define PASS_ANALYSIS false
-IGC_INITIALIZE_PASS_BEGIN(DisableLICMForSpecificLoops, PASS_FLAG, PASS_DESC, PASS_CFG_ONLY, PASS_ANALYSIS)
-IGC_INITIALIZE_PASS_END(DisableLICMForSpecificLoops, PASS_FLAG, PASS_DESC, PASS_CFG_ONLY, PASS_ANALYSIS)
-
+IGC_INITIALIZE_PASS_BEGIN(SpecialCasesDisableLICM, PASS_FLAG, PASS_DESC, PASS_CFG_ONLY, PASS_ANALYSIS)
+IGC_INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
+IGC_INITIALIZE_PASS_END(SpecialCasesDisableLICM, PASS_FLAG, PASS_DESC, PASS_CFG_ONLY, PASS_ANALYSIS)
 
-char DisableLICMForSpecificLoops::ID = 0;
+char SpecialCasesDisableLICM::ID = 0;
 
-DisableLICMForSpecificLoops::DisableLICMForSpecificLoops() : LoopPass(ID)
+SpecialCasesDisableLICM::SpecialCasesDisableLICM() : FunctionPass(ID)
 {
-    initializeDisableLICMForSpecificLoopsPass(*PassRegistry::getPassRegistry());
+    initializeSpecialCasesDisableLICMPass(*PassRegistry::getPassRegistry());
 }
 
-bool DisableLICMForSpecificLoops::runOnLoop(Loop* L, LPPassManager& LPM)
+bool SpecialCasesDisableLICM::runOnFunction(llvm::Function& F)
 {
     bool Changed = false;
+    LoopInfo* LI = nullptr;
 
-    if (!L->getHeader() || !L->getLoopLatch())
-        return false;
+    auto getLoopInfo = [&]() -> LoopInfo* {
+        if (nullptr == LI)
+            return &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
+        return LI;
+    };
 
-    // Disable LICM optimization by adding llvm.licm.disable
-    // - when Loop depends on SIMD Lane Id and operates on local memory
-    // - when shader contains a large number of BBs that may trigger stack overflow
-    //   from memory SSA updater
+    if (constexpr size_t HIGH_BB_THRESHOLD_FOR_LICM = 2500;
+        F.size() > HIGH_BB_THRESHOLD_FOR_LICM)
+    {
+        LI = getLoopInfo();
+
+        if (constexpr size_t HIGH_LOOP_THRESHOLD_FOR_LICM = 450;
+            llvm::size(*LI) > HIGH_LOOP_THRESHOLD_FOR_LICM)
+        {
+            for (auto* L : *LI)
+                AddLICMDisableMedatadaToSpecificLoop(*L);
 
-    if (constexpr size_t BB_LIMIT_FOR_LICM = 2500;
-        L->getHeader()->getParent()->size() > BB_LIMIT_FOR_LICM ||
-        (LoopHasLoadFromLocalAddressSpace(*L) && LoopDependsOnSIMDLaneId(*L)))
+            Changed = true;
+        }
+    }
+
+    if (!Changed)
     {
-        Changed |= AddLICMDisableMedatadaToSpecificLoop(*L);
+        LI = getLoopInfo();
+
+        for (auto* L : *LI)
+        {
+            if (LoopHasLoadFromLocalAddressSpace(*L) && LoopDependsOnSIMDLaneId(*L))
+                Changed |= AddLICMDisableMedatadaToSpecificLoop(*L);
+        }
     }
 
     return Changed;
 }
 
-bool DisableLICMForSpecificLoops::LoopHasLoadFromLocalAddressSpace(const Loop& L)
+bool SpecialCasesDisableLICM::LoopHasLoadFromLocalAddressSpace(const Loop& L)
 {
     for (BasicBlock* BB : L.blocks())
     {
@@ -1236,7 +1262,7 @@ bool DisableLICMForSpecificLoops::LoopHasLoadFromLocalAddressSpace(const Loop& L
     return false;
 }
 
-bool DisableLICMForSpecificLoops::LoopDependsOnSIMDLaneId(const Loop& L)
+bool SpecialCasesDisableLICM::LoopDependsOnSIMDLaneId(const Loop& L)
 {
     auto ComeFromSIMDLaneID = [](Value* I)
     {
@@ -1264,7 +1290,7 @@ bool DisableLICMForSpecificLoops::LoopDependsOnSIMDLaneId(const Loop& L)
     return false;
 }
 
-bool DisableLICMForSpecificLoops::AddLICMDisableMedatadaToSpecificLoop(Loop& L)
+bool SpecialCasesDisableLICM::AddLICMDisableMedatadaToSpecificLoop(Loop& L)
 {
     LLVMContext& context = L.getHeader()->getContext();
 
@@ -1283,9 +1309,9 @@ bool DisableLICMForSpecificLoops::AddLICMDisableMedatadaToSpecificLoop(Loop& L)
 
 namespace IGC
 {
-    LoopPass* createDisableLICMForSpecificLoops()
+    FunctionPass* createSpecialCasesDisableLICM()
     {
-        return new DisableLICMForSpecificLoops();
+        return new SpecialCasesDisableLICM();
     }
 }
 

IGC/Compiler/CustomLoopOpt.hpp

@@ -159,7 +159,7 @@ namespace IGC
 
     llvm::LoopPass* createLoopHoistConstant();
 
-    llvm::LoopPass* createDisableLICMForSpecificLoops();
+    llvm::FunctionPass* createSpecialCasesDisableLICM();
 
     llvm::FunctionPass *createLoopSplitWidePHIs();
 

IGC/Compiler/InitializePasses.h

@@ -1,6 +1,6 @@
 /*========================== begin_copyright_notice ============================
 
-Copyright (C) 2017-2022 Intel Corporation
+Copyright (C) 2017-2024 Intel Corporation
 
 SPDX-License-Identifier: MIT
 
@@ -209,7 +209,7 @@ void initializeSampleMultiversioningPass(llvm::PassRegistry&);
 void initializeLoopCanonicalizationPass(llvm::PassRegistry&);
 void initializeLoopSplitWidePHIsPass(llvm::PassRegistry&);
 void initializeLoopHoistConstantPass(llvm::PassRegistry&);
-void initializeDisableLICMForSpecificLoopsPass(llvm::PassRegistry&);
+void initializeSpecialCasesDisableLICMPass(llvm::PassRegistry&);
 void initializeMemOptPass(llvm::PassRegistry&);
 void initializeLdStCombinePass(llvm::PassRegistry&);
 void initializeBIFTransformsPass(llvm::PassRegistry&);

IGC/Compiler/tests/DisableLICMForSpecificLoops/add_licm_disable_metadata.ll renamed to IGC/Compiler/tests/SpecialCasesDisableLICM/add_licm_disable_metadata.ll

@@ -1,14 +1,14 @@
 ;=========================== begin_copyright_notice ============================
 ;
-; Copyright (C) 2023 Intel Corporation
+; Copyright (C) 2024 Intel Corporation
 ;
 ; SPDX-License-Identifier: MIT
 ;
 ;============================ end_copyright_notice =============================
 ;
-; RUN: igc_opt --igc-disable-licm-for-specific-loops -S < %s | FileCheck %s
+; RUN: igc_opt --igc-special-cases-disable-licm -S < %s | FileCheck %s
 ; ------------------------------------------------
-; DisableLICMForSpecificLoops
+; SpecialCasesDisableLICM
 ; ------------------------------------------------
 
 

IGC/Compiler/tests/DisableLICMForSpecificLoops/add_licm_disable_metadata_multipleLoops.ll renamed to IGC/Compiler/tests/SpecialCasesDisableLICM/add_licm_disable_metadata_multipleLoops.ll

@@ -1,14 +1,14 @@
 ;=========================== begin_copyright_notice ============================
 ;
-; Copyright (C) 2023 Intel Corporation
+; Copyright (C) 2024 Intel Corporation
 ;
 ; SPDX-License-Identifier: MIT
 ;
 ;============================ end_copyright_notice =============================
 ;
-; RUN: igc_opt --igc-disable-licm-for-specific-loops -S < %s | FileCheck %s
+; RUN: igc_opt --igc-special-cases-disable-licm -S < %s | FileCheck %s
 ; ------------------------------------------------
-; DisableLICMForSpecificLoops
+; SpecialCasesDisableLICM
 ; ------------------------------------------------
 
 

IGC/Compiler/tests/DisableLICMForSpecificLoops/does_not_add_licm_disable_metadata_when_no_local_memory_load.ll renamed to IGC/Compiler/tests/SpecialCasesDisableLICM/does_not_add_licm_disable_metadata_when_no_local_memory_load.ll

@@ -1,14 +1,14 @@
 ;=========================== begin_copyright_notice ============================
 ;
-; Copyright (C) 2023 Intel Corporation
+; Copyright (C) 2024 Intel Corporation
 ;
 ; SPDX-License-Identifier: MIT
 ;
 ;============================ end_copyright_notice =============================
 ;
-; RUN: igc_opt --igc-disable-licm-for-specific-loops -S < %s | FileCheck %s
+; RUN: igc_opt --igc-special-cases-disable-licm -S < %s | FileCheck %s
 ; ------------------------------------------------
-; DisableLICMForSpecificLoops
+; SpecialCasesDisableLICM
 ; ------------------------------------------------
 
 

IGC/Compiler/tests/DisableLICMForSpecificLoops/does_not_add_licm_disable_metadata_when_no_simdLaneId.ll renamed to IGC/Compiler/tests/SpecialCasesDisableLICM/does_not_add_licm_disable_metadata_when_no_simdLaneId.ll

@@ -1,14 +1,14 @@
 ;=========================== begin_copyright_notice ============================
 ;
-; Copyright (C) 2023 Intel Corporation
+; Copyright (C) 2024 Intel Corporation
 ;
 ; SPDX-License-Identifier: MIT
 ;
 ;============================ end_copyright_notice =============================
 ;
-; RUN: igc_opt --igc-disable-licm-for-specific-loops -S < %s | FileCheck %s
+; RUN: igc_opt --igc-special-cases-disable-licm -S < %s | FileCheck %s
 ; ------------------------------------------------
-; DisableLICMForSpecificLoops
+; SpecialCasesDisableLICM
 ; ------------------------------------------------