[CodeGen] Port GlobalMerge to new pass manager

[paperchalice]

No description provided.

[llvmbot]

@llvm/pr-subscribers-backend-aarch64
@llvm/pr-subscribers-backend-risc-v
@llvm/pr-subscribers-backend-arm

@llvm/pr-subscribers-llvm-transforms

Author: None (paperchalice)

Changes

---

Patch is 20.42 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/77474.diff

12 Files Affected:

• (modified) llvm/include/llvm/CodeGen/CodeGenPassBuilder.h (+5)
• (added) llvm/include/llvm/CodeGen/GlobalMerge.h (+48)
• (modified) llvm/include/llvm/CodeGen/MachinePassRegistry.def (+2-1)
• (modified) llvm/lib/CodeGen/GlobalMerge.cpp (+85-82)
• (modified) llvm/lib/Passes/PassBuilder.cpp (+27)
• (modified) llvm/lib/Passes/PassRegistry.def (+8-1)
• (modified) llvm/test/Transforms/GlobalMerge/alignment-2.ll (+1)
• (modified) llvm/test/Transforms/GlobalMerge/alignment.ll (+1)
• (modified) llvm/test/Transforms/GlobalMerge/basic.ll (+1)
• (modified) llvm/test/Transforms/GlobalMerge/debug-info.ll (+1)
• (modified) llvm/test/Transforms/GlobalMerge/eh-filter.ll (+1)
• (modified) llvm/test/Transforms/GlobalMerge/used.ll (+1)

diff --git a/llvm/include/llvm/CodeGen/CodeGenPassBuilder.h b/llvm/include/llvm/CodeGen/CodeGenPassBuilder.h
index a1382a5e8e4036..86020a106d41d5 100644
--- a/llvm/include/llvm/CodeGen/CodeGenPassBuilder.h
+++ b/llvm/include/llvm/CodeGen/CodeGenPassBuilder.h
@@ -28,6 +28,7 @@
 #include "llvm/CodeGen/ExpandMemCmp.h"
 #include "llvm/CodeGen/ExpandReductions.h"
 #include "llvm/CodeGen/GCMetadata.h"
+#include "llvm/CodeGen/GlobalMerge.h" 
 #include "llvm/CodeGen/IndirectBrExpand.h"
 #include "llvm/CodeGen/InterleavedAccess.h"
 #include "llvm/CodeGen/InterleavedLoadCombine.h"
@@ -290,6 +291,9 @@ template <typename DerivedT> class CodeGenPassBuilder {
                                    inconvertibleErrorCode());
   }
 
+  /// Target can override this to add GlobalMergePass before all IR passes.
+  void addGlobalMergePass(AddIRPass &) const {}
+
   /// Add passes that optimize instruction level parallelism for out-of-order
   /// targets. These passes are run while the machine code is still in SSA
   /// form, so they can use MachineTraceMetrics to control their heuristics.
@@ -603,6 +607,7 @@ CodeGenPassBuilder<Derived>::getPassNameFromLegacyName(StringRef Name) const {
 
 template <typename Derived>
 void CodeGenPassBuilder<Derived>::addISelPasses(AddIRPass &addPass) const {
+  derived().addGlobalMergePass(addPass);
   if (TM.useEmulatedTLS())
     addPass(LowerEmuTLSPass());
 
diff --git a/llvm/include/llvm/CodeGen/GlobalMerge.h b/llvm/include/llvm/CodeGen/GlobalMerge.h
new file mode 100644
index 00000000000000..dcbfb129975741
--- /dev/null
+++ b/llvm/include/llvm/CodeGen/GlobalMerge.h
@@ -0,0 +1,48 @@
+//===- llvm/CodeGen/GlobalMerge.h --------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_GLOBALMERGE_H
+#define LLVM_CODEGEN_GLOBALMERGE_H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+struct GlobalMergeOptions {
+  // FIXME: Infer the maximum possible offset depending on the actual users
+  // (these max offsets are different for the users inside Thumb or ARM
+  // functions), see the code that passes in the offset in the ARM backend
+  // for more information.
+  unsigned MaxOffset = 0;
+  bool GroupByUse = true;
+  bool IgnoreSingleUse = true;
+  bool MergeConst = false;
+  /// Whether we should merge global variables that have external linkage.
+  bool MergeExternal = true;
+  /// Whether we should try to optimize for size only.
+  /// Currently, this applies a dead simple heuristic: only consider globals
+  /// used in minsize functions for merging.
+  /// FIXME: This could learn about optsize, and be used in the cost model.
+  bool SizeOnly = false;
+};
+
+class TargetMachine;
+class GlobalMergePass : public PassInfoMixin<GlobalMergePass> {
+  const TargetMachine *TM;
+  GlobalMergeOptions Options;
+
+public:
+  GlobalMergePass(const TargetMachine *TM, GlobalMergeOptions Options)
+      : TM(TM), Options(Options) {}
+
+  PreservedAnalyses run(Module &M, ModuleAnalysisManager &MAM);
+};
+
+} // namespace llvm
+
+#endif // LLVM_CODEGEN_GLOBALMERGE_H
diff --git a/llvm/include/llvm/CodeGen/MachinePassRegistry.def b/llvm/include/llvm/CodeGen/MachinePassRegistry.def
index cbfd4327da6e64..ebc3ac20ffb032 100644
--- a/llvm/include/llvm/CodeGen/MachinePassRegistry.def
+++ b/llvm/include/llvm/CodeGen/MachinePassRegistry.def
@@ -23,9 +23,10 @@ MODULE_ANALYSIS("pass-instrumentation", PassInstrumentationAnalysis, (PIC))
 #ifndef MODULE_PASS
 #define MODULE_PASS(NAME, PASS_NAME, CONSTRUCTOR)
 #endif
-MODULE_PASS("pre-isel-intrinsic-lowering", PreISelIntrinsicLoweringPass, ())
+MODULE_PASS("global-merge", GlobalMergePass, (TM, GlobalMergeOptions()))
 MODULE_PASS("jmc-instrumenter", JMCInstrumenterPass, ())
 MODULE_PASS("lower-emutls", LowerEmuTLSPass, ())
+MODULE_PASS("pre-isel-intrinsic-lowering", PreISelIntrinsicLoweringPass, ())
 MODULE_PASS("shadow-stack-gc-lowering", ShadowStackGCLoweringPass, ())
 #undef MODULE_PASS
 
diff --git a/llvm/lib/CodeGen/GlobalMerge.cpp b/llvm/lib/CodeGen/GlobalMerge.cpp
index 22b6d31d063495..a2b5cbf7bad9f8 100644
--- a/llvm/lib/CodeGen/GlobalMerge.cpp
+++ b/llvm/lib/CodeGen/GlobalMerge.cpp
@@ -60,6 +60,7 @@
 //
 // ===---------------------------------------------------------------------===//
 
+#include "llvm/CodeGen/GlobalMerge.h"
 #include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SetVector.h"
@@ -137,88 +138,99 @@ STATISTIC(NumMerged, "Number of globals merged");
 
 namespace {
 
-  class GlobalMerge : public FunctionPass {
-    const TargetMachine *TM = nullptr;
-
-    // FIXME: Infer the maximum possible offset depending on the actual users
-    // (these max offsets are different for the users inside Thumb or ARM
-    // functions), see the code that passes in the offset in the ARM backend
-    // for more information.
-    unsigned MaxOffset;
-
-    /// Whether we should try to optimize for size only.
-    /// Currently, this applies a dead simple heuristic: only consider globals
-    /// used in minsize functions for merging.
-    /// FIXME: This could learn about optsize, and be used in the cost model.
-    bool OnlyOptimizeForSize = false;
-
-    /// Whether we should merge global variables that have external linkage.
-    bool MergeExternalGlobals = false;
+class GlobalMergeImpl {
+  const TargetMachine *TM = nullptr;
+  GlobalMergeOptions Opt;
+  bool IsMachO = false;
+
+private:
+  bool doMerge(SmallVectorImpl<GlobalVariable *> &Globals, Module &M,
+               bool isConst, unsigned AddrSpace) const;
+
+  /// Merge everything in \p Globals for which the corresponding bit
+  /// in \p GlobalSet is set.
+  bool doMerge(const SmallVectorImpl<GlobalVariable *> &Globals,
+               const BitVector &GlobalSet, Module &M, bool isConst,
+               unsigned AddrSpace) const;
+
+  /// Check if the given variable has been identified as must keep
+  /// \pre setMustKeepGlobalVariables must have been called on the Module that
+  ///      contains GV
+  bool isMustKeepGlobalVariable(const GlobalVariable *GV) const {
+    return MustKeepGlobalVariables.count(GV);
+  }
 
-    bool IsMachO = false;
+  /// Collect every variables marked as "used" or used in a landing pad
+  /// instruction for this Module.
+  void setMustKeepGlobalVariables(Module &M);
 
-    bool doMerge(SmallVectorImpl<GlobalVariable*> &Globals,
-                 Module &M, bool isConst, unsigned AddrSpace) const;
+  /// Collect every variables marked as "used"
+  void collectUsedGlobalVariables(Module &M, StringRef Name);
 
-    /// Merge everything in \p Globals for which the corresponding bit
-    /// in \p GlobalSet is set.
-    bool doMerge(const SmallVectorImpl<GlobalVariable *> &Globals,
-                 const BitVector &GlobalSet, Module &M, bool isConst,
-                 unsigned AddrSpace) const;
+  /// Keep track of the GlobalVariable that must not be merged away
+  SmallSetVector<const GlobalVariable *, 16> MustKeepGlobalVariables;
 
-    /// Check if the given variable has been identified as must keep
-    /// \pre setMustKeepGlobalVariables must have been called on the Module that
-    ///      contains GV
-    bool isMustKeepGlobalVariable(const GlobalVariable *GV) const {
-      return MustKeepGlobalVariables.count(GV);
-    }
+public:
+  GlobalMergeImpl(const TargetMachine *TM, GlobalMergeOptions Opt)
+      : TM(TM), Opt(Opt) {}
+  bool run(Module &M);
+};
 
-    /// Collect every variables marked as "used" or used in a landing pad
-    /// instruction for this Module.
-    void setMustKeepGlobalVariables(Module &M);
+class GlobalMerge : public FunctionPass {
+  const TargetMachine *TM = nullptr;
+  GlobalMergeOptions Opt;
 
-    /// Collect every variables marked as "used"
-    void collectUsedGlobalVariables(Module &M, StringRef Name);
+public:
+  static char ID; // Pass identification, replacement for typeid.
 
-    /// Keep track of the GlobalVariable that must not be merged away
-    SmallSetVector<const GlobalVariable *, 16> MustKeepGlobalVariables;
+  explicit GlobalMerge() : FunctionPass(ID) {
+    Opt.MaxOffset = GlobalMergeMaxOffset;
+    initializeGlobalMergePass(*PassRegistry::getPassRegistry());
+  }
 
-  public:
-    static char ID;             // Pass identification, replacement for typeid.
+  explicit GlobalMerge(const TargetMachine *TM, unsigned MaximalOffset,
+                       bool OnlyOptimizeForSize, bool MergeExternalGlobals)
+      : FunctionPass(ID), TM(TM) {
+    Opt.MaxOffset = MaximalOffset;
+    Opt.SizeOnly = OnlyOptimizeForSize;
+    Opt.MergeExternal = MergeExternalGlobals;
+    initializeGlobalMergePass(*PassRegistry::getPassRegistry());
+  }
 
-    explicit GlobalMerge()
-        : FunctionPass(ID), MaxOffset(GlobalMergeMaxOffset) {
-      initializeGlobalMergePass(*PassRegistry::getPassRegistry());
-    }
+  bool doInitialization(Module &M) override {
+    GlobalMergeImpl P(TM, Opt);
+    return P.run(M);
+  }
+  bool runOnFunction(Function &F) override { return false; }
 
-    explicit GlobalMerge(const TargetMachine *TM, unsigned MaximalOffset,
-                         bool OnlyOptimizeForSize, bool MergeExternalGlobals)
-        : FunctionPass(ID), TM(TM), MaxOffset(MaximalOffset),
-          OnlyOptimizeForSize(OnlyOptimizeForSize),
-          MergeExternalGlobals(MergeExternalGlobals) {
-      initializeGlobalMergePass(*PassRegistry::getPassRegistry());
-    }
+  StringRef getPassName() const override { return "Merge internal globals"; }
 
-    bool doInitialization(Module &M) override;
-    bool runOnFunction(Function &F) override;
-    bool doFinalization(Module &M) override;
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesCFG();
+    FunctionPass::getAnalysisUsage(AU);
+  }
+};
 
-    StringRef getPassName() const override { return "Merge internal globals"; }
+} // end anonymous namespace
 
-    void getAnalysisUsage(AnalysisUsage &AU) const override {
-      AU.setPreservesCFG();
-      FunctionPass::getAnalysisUsage(AU);
-    }
-  };
+PreservedAnalyses GlobalMergePass::run(Module &M, ModuleAnalysisManager &) {
+  GlobalMergeImpl P(TM, Options);
+  bool Changed = P.run(M);
+  if (!Changed)
+    return PreservedAnalyses::all();
 
-} // end anonymous namespace
+  PreservedAnalyses PA;
+  PA.preserveSet<CFGAnalyses>();
+  return PA;
+}
 
 char GlobalMerge::ID = 0;
 
 INITIALIZE_PASS(GlobalMerge, DEBUG_TYPE, "Merge global variables", false, false)
 
-bool GlobalMerge::doMerge(SmallVectorImpl<GlobalVariable*> &Globals,
-                          Module &M, bool isConst, unsigned AddrSpace) const {
+bool GlobalMergeImpl::doMerge(SmallVectorImpl<GlobalVariable *> &Globals,
+                              Module &M, bool isConst,
+                              unsigned AddrSpace) const {
   auto &DL = M.getDataLayout();
   // FIXME: Find better heuristics
   llvm::stable_sort(
@@ -333,7 +345,7 @@ bool GlobalMerge::doMerge(SmallVectorImpl<GlobalVariable*> &Globals,
         Function *ParentFn = I->getParent()->getParent();
 
         // If we're only optimizing for size, ignore non-minsize functions.
-        if (OnlyOptimizeForSize && !ParentFn->hasMinSize())
+        if (Opt.SizeOnly && !ParentFn->hasMinSize())
           continue;
 
         size_t UGSIdx = GlobalUsesByFunction[ParentFn];
@@ -434,9 +446,9 @@ bool GlobalMerge::doMerge(SmallVectorImpl<GlobalVariable*> &Globals,
   return Changed;
 }
 
-bool GlobalMerge::doMerge(const SmallVectorImpl<GlobalVariable *> &Globals,
-                          const BitVector &GlobalSet, Module &M, bool isConst,
-                          unsigned AddrSpace) const {
+bool GlobalMergeImpl::doMerge(const SmallVectorImpl<GlobalVariable *> &Globals,
+                              const BitVector &GlobalSet, Module &M,
+                              bool isConst, unsigned AddrSpace) const {
   assert(Globals.size() > 1);
 
   Type *Int32Ty = Type::getInt32Ty(M.getContext());
@@ -467,7 +479,7 @@ bool GlobalMerge::doMerge(const SmallVectorImpl<GlobalVariable *> &Globals,
       unsigned Padding = alignTo(MergedSize, Alignment) - MergedSize;
       MergedSize += Padding;
       MergedSize += DL.getTypeAllocSize(Ty);
-      if (MergedSize > MaxOffset) {
+      if (MergedSize > Opt.MaxOffset) {
         break;
       }
       if (Padding) {
@@ -563,7 +575,7 @@ bool GlobalMerge::doMerge(const SmallVectorImpl<GlobalVariable *> &Globals,
   return Changed;
 }
 
-void GlobalMerge::collectUsedGlobalVariables(Module &M, StringRef Name) {
+void GlobalMergeImpl::collectUsedGlobalVariables(Module &M, StringRef Name) {
   // Extract global variables from llvm.used array
   const GlobalVariable *GV = M.getGlobalVariable(Name);
   if (!GV || !GV->hasInitializer()) return;
@@ -577,7 +589,7 @@ void GlobalMerge::collectUsedGlobalVariables(Module &M, StringRef Name) {
       MustKeepGlobalVariables.insert(G);
 }
 
-void GlobalMerge::setMustKeepGlobalVariables(Module &M) {
+void GlobalMergeImpl::setMustKeepGlobalVariables(Module &M) {
   collectUsedGlobalVariables(M, "llvm.used");
   collectUsedGlobalVariables(M, "llvm.compiler.used");
 
@@ -604,7 +616,7 @@ void GlobalMerge::setMustKeepGlobalVariables(Module &M) {
   }
 }
 
-bool GlobalMerge::doInitialization(Module &M) {
+bool GlobalMergeImpl::run(Module &M) {
   if (!EnableGlobalMerge)
     return false;
 
@@ -632,7 +644,7 @@ bool GlobalMerge::doInitialization(Module &M) {
     if (TM && !TM->shouldAssumeDSOLocal(M, &GV))
       continue;
 
-    if (!(MergeExternalGlobals && GV.hasExternalLinkage()) &&
+    if (!(Opt.MergeExternal && GV.hasExternalLinkage()) &&
         !GV.hasInternalLinkage())
       continue;
 
@@ -659,7 +671,7 @@ bool GlobalMerge::doInitialization(Module &M) {
       continue;
 
     Type *Ty = GV.getValueType();
-    if (DL.getTypeAllocSize(Ty) < MaxOffset) {
+    if (DL.getTypeAllocSize(Ty) < Opt.MaxOffset) {
       if (TM &&
           TargetLoweringObjectFile::getKindForGlobal(&GV, *TM).isBSS())
         BSSGlobals[{AddressSpace, Section}].push_back(&GV);
@@ -686,15 +698,6 @@ bool GlobalMerge::doInitialization(Module &M) {
   return Changed;
 }
 
-bool GlobalMerge::runOnFunction(Function &F) {
-  return false;
-}
-
-bool GlobalMerge::doFinalization(Module &M) {
-  MustKeepGlobalVariables.clear();
-  return false;
-}
-
 Pass *llvm::createGlobalMergePass(const TargetMachine *TM, unsigned Offset,
                                   bool OnlyOptimizeForSize,
                                   bool MergeExternalByDefault) {
diff --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
index 27bfe12127cc2c..c3acfcdfe5ab67 100644
--- a/llvm/lib/Passes/PassBuilder.cpp
+++ b/llvm/lib/Passes/PassBuilder.cpp
@@ -80,6 +80,7 @@
 #include "llvm/CodeGen/ExpandLargeFpConvert.h"
 #include "llvm/CodeGen/ExpandMemCmp.h"
 #include "llvm/CodeGen/GCMetadata.h"
+#include "llvm/CodeGen/GlobalMerge.h"
 #include "llvm/CodeGen/HardwareLoops.h"
 #include "llvm/CodeGen/IndirectBrExpand.h"
 #include "llvm/CodeGen/InterleavedAccess.h"
@@ -1160,6 +1161,32 @@ Expected<bool> parseWinEHPrepareOptions(StringRef Params) {
                                "WinEHPreparePass");
 }
 
+Expected<GlobalMergeOptions> parseGlobalMergeOptions(StringRef Params) {
+  GlobalMergeOptions Result;
+  while (!Params.empty()) {
+    StringRef ParamName;
+    std::tie(ParamName, Params) = Params.split(';');
+
+    bool Enable = !ParamName.consume_front("no-");
+    if (ParamName == "group-by-use")
+      Result.GroupByUse = Enable;
+    else if (ParamName == "ignore-single-use")
+      Result.IgnoreSingleUse = Enable;
+    else if (ParamName == "merge-const")
+      Result.MergeConst = Enable;
+    else if (ParamName == "merge-external")
+      Result.MergeExternal = Enable;
+    else if (ParamName.consume_front("max-offset=")) {
+      if (ParamName.getAsInteger(0, Result.MaxOffset))
+        return make_error<StringError>(
+            formatv("invalid GlobalMergePass parameter '{0}' ", ParamName)
+                .str(),
+            inconvertibleErrorCode());
+    }
+  }
+  return Result;
+}
+
 } // namespace
 
 /// Tests whether a pass name starts with a valid prefix for a default pipeline
diff --git a/llvm/lib/Passes/PassRegistry.def b/llvm/lib/Passes/PassRegistry.def
index bda36bd8c107c9..a5d986a6379473 100644
--- a/llvm/lib/Passes/PassRegistry.def
+++ b/llvm/lib/Passes/PassRegistry.def
@@ -151,6 +151,13 @@ MODULE_PASS_WITH_PARAMS(
     "asan", "AddressSanitizerPass",
     [](AddressSanitizerOptions Opts) { return AddressSanitizerPass(Opts); },
     parseASanPassOptions, "kernel")
+MODULE_PASS_WITH_PARAMS(
+    "global-merge", "GlobalMergePass",
+    [TM = TM](GlobalMergeOptions Opts) { return GlobalMergePass(TM, Opts); },
+    parseGlobalMergeOptions,
+    "group-by-use;ignore-single-use;max-offset=N;merge-const;merge-external;"
+    "no-group-by-use;no-ignore-single-use;no-merge-const;no-merge-external;"
+    "size-only")
 MODULE_PASS_WITH_PARAMS(
     "globaldce", "GlobalDCEPass",
     [](bool InLTOPostLink) { return GlobalDCEPass(InLTOPostLink); },
@@ -421,7 +428,7 @@ FUNCTION_PASS("structurizecfg", StructurizeCFGPass())
 FUNCTION_PASS("tailcallelim", TailCallElimPass())
 FUNCTION_PASS("tlshoist", TLSVariableHoistPass())
 FUNCTION_PASS("transform-warning", WarnMissedTransformationsPass())
-FUNCTION_PASS("trigger-verifier-error", TriggerVerifierErrorPass())  
+FUNCTION_PASS("trigger-verifier-error", TriggerVerifierErrorPass())
 FUNCTION_PASS("tsan", ThreadSanitizerPass())
 FUNCTION_PASS("typepromotion", TypePromotionPass(TM))
 FUNCTION_PASS("unify-loop-exits", UnifyLoopExitsPass())
diff --git a/llvm/test/Transforms/GlobalMerge/alignment-2.ll b/llvm/test/Transforms/GlobalMerge/alignment-2.ll
index 194421613e81e8..99657d8f6ba7d5 100644
--- a/llvm/test/Transforms/GlobalMerge/alignment-2.ll
+++ b/llvm/test/Transforms/GlobalMerge/alignment-2.ll
@@ -1,4 +1,5 @@
 ; RUN: opt -global-merge -global-merge-max-offset=100 -S -o - %s | FileCheck %s
+; RUN: opt -passes='global-merge<max-offset=100>' -S -o - %s | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/GlobalMerge/alignment.ll b/llvm/test/Transforms/GlobalMerge/alignment.ll
index e3c3eb3ce065b0..a787791369c625 100644
--- a/llvm/test/Transforms/GlobalMerge/alignment.ll
+++ b/llvm/test/Transforms/GlobalMerge/alignment.ll
@@ -1,4 +1,5 @@
 ; RUN: opt -global-merge -global-merge-max-offset=100 -S -o - %s | FileCheck %s
+; RUN: opt -passes='global-merge<max-offset=100>' -S -o - %s | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/GlobalMerge/basic.ll b/llvm/test/Transforms/GlobalMerge/basic.ll
index 69d897d04a1a02..67e2b70220a783 100644
--- a/llvm/test/Transforms/GlobalMerge/basic.ll
+++ b/llvm/test/Transforms/GlobalMerge/basic.ll
@@ -1,4 +1,5 @@
 ; RUN: opt -global-merge -global-merge-max-offset=100 -S -o - %s | FileCheck %s
+; RUN: opt -passes='global-merge<max-offset=100>' -S -o - %s | FileCheck %s
 
 target datalayout = "e-p:64:64"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/GlobalMerge/debug-info.ll b/llvm/test/Transforms/GlobalMerge/debug-info.ll
index b20e59007716eb..8a535b5d3873ac 100644
--- a/llvm/test/Transforms/GlobalMerge/debug-info.ll
+++ b/llvm/test/Transforms/GlobalMerge/debug-info.ll
@@ -1,4 +1,5 @@
 ; RUN: opt -global-merge -global-merge-max-offset=100 -S -o - %s | FileCheck %s
+; RUN: opt -passes='global-merge<max-offset=100>' -S -o - %s | FileCheck %s
 
 source_filename = "test/Transforms/GlobalMerge/debug-info.ll"
 target datalayout = "e-p:64:64"
diff --git a/llvm/test/Transforms/GlobalMerge/eh-filter.ll b/llvm/test/Transforms/GlobalMerge/eh-filter.ll
index 3500865331aabf..28f7905c37057a 100644
--- a/llvm/test/Transforms/GlobalMerge/eh-filter.ll
+++ b/llvm/test/Transforms/GlobalMerge/eh-filter.ll
@@ -1,5 +1,6 @@
 ; REQUIRES: asserts
 ; RUN: opt -global-merge -debug-only=global-merge -S -o - %s 2>&1 | FileCheck %s
+; RUN: opt -passes='global-merge' -debug-only=global-merge -S -o - %s 2>&1 | FileCheck %s
 
 ;; Checks from the debug info.
 ; CHECK:      Number of GV that must be kept:  5
diff --git a/llvm/test/Transforms/GlobalMerge/used.ll b/...
[truncated]

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[arsenm]

Why is this here? Is there an analogous hook in the old PM?

[paperchalice]

Some backends, e.g. ARM, use this pass. The legacy version transforms module in doInitialization rather than runOnFunction. So, add this hook to add global merge and add this pass in front of the pipeline.

[arsenm]

Something doesn't make sense. Why is this a function pass, that only changes the module and does all the work in doInitalization? Should it be converted to a ModulePass?

[paperchalice]

It should be a module pass in theory, will convert it.

[paperchalice]

Something doesn't make sense. Why is this a function pass, that only changes the module and does all the work in doInitalization? Should it be converted to a ModulePass?

Unfortunately, GlobalMerge must run before the doInitialization of AsmPrinter to keep the dwaf info.

May split AsmPrinter into multiple passes in future, one reason is that the doFinalization in AsmPrinter is in fact a module IR pass, but now is too early and off-topic.

[arsenm]

Seems to be GlobalMerge should be run earlier than it is now. I would expect it to run before CodeGenPrepare at least (if it even belongs in the codegen pipeline in the first place)

[efriedma-quic]

It sounds like it already is running at the very beginning of the codegen pipeline? doInitialization runs before any passes, I think.

If it did run in the optimization pipeline, it would have to be very late; the target hooks use information about the exact load/store ops that access the global to pick appropriate thresholds. And it messes with alias analysis a bit for mutable variables. So ultimately it wouldn't be much different from running it in early codegen. (Which is really too early for constants, given the pass can't see constant pools, but that's a different issue.)

[paperchalice]

It is a CodeGen only IR pass, but some tests run this pass in opt.

[arsenm]

Seems to be GlobalMerge should be run earlier than it is now. I would expect it to run before CodeGenPrepare at least (if it even belongs in the codegen pipeline in the first place)