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[MergeFunctions] Add support to run the pass over a set of function pointers #111045

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This modification will enable the usage of MergeFunctions as a standalone library. Currently, MergeFunctions can only be applied to an entire module. By adopting this change, developers will gain the flexibility to reuse the MergeFunctions code within their own projects, choosing which functions to merge; hence, promoting code reusability. Notice that this modification will not break backward compatibility, because MergeFunctions will still work as a pass after the modification.

Summary of Changes:

  • Modified the MergeFunctionsPass to allow running the pass over a set of function pointers.
  • This behavior is optional and doesn't interfere with the existing functionality of running the pass on the entire Module.
  • Added unit tests to assert the correctness of the updated implementation, ensuring that function merging works as expected when run on both sets of pointers and full modules.

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llvmbot commented Oct 3, 2024

@llvm/pr-subscribers-llvm-transforms

Author: Rafael Eckstein (Casperento)

Changes

This modification will enable the usage of MergeFunctions as a standalone library. Currently, MergeFunctions can only be applied to an entire module. By adopting this change, developers will gain the flexibility to reuse the MergeFunctions code within their own projects, choosing which functions to merge; hence, promoting code reusability. Notice that this modification will not break backward compatibility, because MergeFunctions will still work as a pass after the modification.

Summary of Changes:

  • Modified the MergeFunctionsPass to allow running the pass over a set of function pointers.
  • This behavior is optional and doesn't interfere with the existing functionality of running the pass on the entire Module.
  • Added unit tests to assert the correctness of the updated implementation, ensuring that function merging works as expected when run on both sets of pointers and full modules.

Full diff: https://github.com/llvm/llvm-project/pull/111045.diff

5 Files Affected:

  • (modified) llvm/include/llvm/Transforms/IPO/MergeFunctions.h (+7)
  • (modified) llvm/lib/Transforms/IPO/MergeFunctions.cpp (+61-2)
  • (modified) llvm/unittests/Transforms/Utils/CMakeLists.txt (+1)
  • (added) llvm/unittests/Transforms/Utils/MergeFunctionsTest.cpp (+271)
  • (modified) llvm/utils/gn/secondary/llvm/unittests/Transforms/Utils/BUILD.gn (+1)
diff --git a/llvm/include/llvm/Transforms/IPO/MergeFunctions.h b/llvm/include/llvm/Transforms/IPO/MergeFunctions.h
index 822f0fd99188d0..1b3b1d22f11e28 100644
--- a/llvm/include/llvm/Transforms/IPO/MergeFunctions.h
+++ b/llvm/include/llvm/Transforms/IPO/MergeFunctions.h
@@ -15,7 +15,10 @@
 #ifndef LLVM_TRANSFORMS_IPO_MERGEFUNCTIONS_H
 #define LLVM_TRANSFORMS_IPO_MERGEFUNCTIONS_H
 
+#include "llvm/IR/Function.h"
 #include "llvm/IR/PassManager.h"
+#include <map>
+#include <set>
 
 namespace llvm {
 
@@ -25,6 +28,10 @@ class Module;
 class MergeFunctionsPass : public PassInfoMixin<MergeFunctionsPass> {
 public:
   PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
+
+  static bool runOnModule(Module &M);
+  static std::pair<bool, std::map<Function *, Function *>>
+  runOnFunctions(std::set<Function *> &F);
 };
 
 } // end namespace llvm
diff --git a/llvm/lib/Transforms/IPO/MergeFunctions.cpp b/llvm/lib/Transforms/IPO/MergeFunctions.cpp
index b50a700e09038f..a434d7920b6ccf 100644
--- a/llvm/lib/Transforms/IPO/MergeFunctions.cpp
+++ b/llvm/lib/Transforms/IPO/MergeFunctions.cpp
@@ -123,6 +123,7 @@
 #include <algorithm>
 #include <cassert>
 #include <iterator>
+#include <map>
 #include <set>
 #include <utility>
 #include <vector>
@@ -198,6 +199,8 @@ class MergeFunctions {
   }
 
   bool runOnModule(Module &M);
+  bool runOnFunctions(std::set<Function *> &F);
+  std::map<Function *, Function *> &getDelToNewMap();
 
 private:
   // The function comparison operator is provided here so that FunctionNodes do
@@ -298,17 +301,31 @@ class MergeFunctions {
   // dangling iterators into FnTree. The invariant that preserves this is that
   // there is exactly one mapping F -> FN for each FunctionNode FN in FnTree.
   DenseMap<AssertingVH<Function>, FnTreeType::iterator> FNodesInTree;
+
+  /// Deleted-New functions mapping
+  std::map<Function *, Function *> DelToNewMap;
 };
 } // end anonymous namespace
 
 PreservedAnalyses MergeFunctionsPass::run(Module &M,
                                           ModuleAnalysisManager &AM) {
-  MergeFunctions MF;
-  if (!MF.runOnModule(M))
+  if (!MergeFunctionsPass::runOnModule(M))
     return PreservedAnalyses::all();
   return PreservedAnalyses::none();
 }
 
+bool MergeFunctionsPass::runOnModule(Module &M) {
+  MergeFunctions MF;
+  return MF.runOnModule(M);
+}
+
+std::pair<bool, std::map<Function *, Function *>>
+MergeFunctionsPass::runOnFunctions(std::set<Function *> &F) {
+  MergeFunctions MF;
+  bool MergeResult = MF.runOnFunctions(F);
+  return {MergeResult, MF.getDelToNewMap()};
+}
+
 #ifndef NDEBUG
 bool MergeFunctions::doFunctionalCheck(std::vector<WeakTrackingVH> &Worklist) {
   if (const unsigned Max = NumFunctionsForVerificationCheck) {
@@ -468,6 +485,47 @@ bool MergeFunctions::runOnModule(Module &M) {
   return Changed;
 }
 
+bool MergeFunctions::runOnFunctions(std::set<Function *> &F) {
+  bool Changed = false;
+  std::vector<std::pair<IRHash, Function *>> HashedFuncs;
+  for (Function *Func : F) {
+    if (isEligibleForMerging(*Func)) {
+      HashedFuncs.push_back({StructuralHash(*Func), Func});
+    }
+  }
+  llvm::stable_sort(HashedFuncs, less_first());
+  auto S = HashedFuncs.begin();
+  for (auto I = HashedFuncs.begin(), IE = HashedFuncs.end(); I != IE; ++I) {
+    if ((I != S && std::prev(I)->first == I->first) ||
+        (std::next(I) != IE && std::next(I)->first == I->first)) {
+      Deferred.push_back(WeakTrackingVH(I->second));
+    }
+  }
+  do {
+    std::vector<WeakTrackingVH> Worklist;
+    Deferred.swap(Worklist);
+    LLVM_DEBUG(dbgs() << "size of function: " << F.size() << '\n');
+    LLVM_DEBUG(dbgs() << "size of worklist: " << Worklist.size() << '\n');
+    for (WeakTrackingVH &I : Worklist) {
+      if (!I)
+        continue;
+      Function *F = cast<Function>(I);
+      if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage()) {
+        Changed |= insert(F);
+      }
+    }
+    LLVM_DEBUG(dbgs() << "size of FnTree: " << FnTree.size() << '\n');
+  } while (!Deferred.empty());
+  FnTree.clear();
+  FNodesInTree.clear();
+  GlobalNumbers.clear();
+  return Changed;
+}
+
+std::map<Function *, Function *> &MergeFunctions::getDelToNewMap() {
+  return this->DelToNewMap;
+}
+
 // Replace direct callers of Old with New.
 void MergeFunctions::replaceDirectCallers(Function *Old, Function *New) {
   for (Use &U : llvm::make_early_inc_range(Old->uses())) {
@@ -1004,6 +1062,7 @@ bool MergeFunctions::insert(Function *NewFunction) {
 
   Function *DeleteF = NewFunction;
   mergeTwoFunctions(OldF.getFunc(), DeleteF);
+  this->DelToNewMap.emplace(DeleteF, OldF.getFunc());
   return true;
 }
 
diff --git a/llvm/unittests/Transforms/Utils/CMakeLists.txt b/llvm/unittests/Transforms/Utils/CMakeLists.txt
index 5c7ec28709c169..7effa5d8e7d6d2 100644
--- a/llvm/unittests/Transforms/Utils/CMakeLists.txt
+++ b/llvm/unittests/Transforms/Utils/CMakeLists.txt
@@ -26,6 +26,7 @@ add_llvm_unittest(UtilsTests
   LoopUtilsTest.cpp
   MemTransferLowering.cpp
   ModuleUtilsTest.cpp
+  MergeFunctionsTest.cpp
   ScalarEvolutionExpanderTest.cpp
   SizeOptsTest.cpp
   SSAUpdaterBulkTest.cpp
diff --git a/llvm/unittests/Transforms/Utils/MergeFunctionsTest.cpp b/llvm/unittests/Transforms/Utils/MergeFunctionsTest.cpp
new file mode 100644
index 00000000000000..696c5391ef4f68
--- /dev/null
+++ b/llvm/unittests/Transforms/Utils/MergeFunctionsTest.cpp
@@ -0,0 +1,271 @@
+//===- MergeFunctionsTest.cpp - Unit tests for
+//MergeFunctionsPass-----------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/IPO/MergeFunctions.h"
+#include "llvm/AsmParser/Parser.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Support/SourceMgr.h"
+#include "gtest/gtest.h"
+#include <memory>
+
+using namespace llvm;
+
+namespace {
+
+TEST(MergeFunctions, TrueOutputModuleTest) {
+  LLVMContext Ctx;
+  SMDiagnostic Err;
+  std::unique_ptr<Module> M(parseAssemblyString(R"invalid(
+        @.str = private unnamed_addr constant [10 x i8] c"On f: %d\0A\00", align 1
+        @.str.1 = private unnamed_addr constant [13 x i8] c"On main: %d\0A\00", align 1
+
+        define dso_local i32 @f(i32 noundef %arg) #0 {
+            entry:
+                %add109 = call i32 @_slice_add10(i32 %arg)
+                %call = call i32 (ptr, ...) @printf(ptr noundef @.str, i32 noundef %add109)
+                ret i32 %add109
+        }
+
+        declare i32 @printf(ptr noundef, ...) #1
+
+        define dso_local i32 @main(i32 noundef %argc, ptr noundef %argv) #0 {
+            entry:
+                %add99 = call i32 @_slice_add10(i32 %argc)
+                %call = call i32 @f(i32 noundef 2)
+                %sub = sub nsw i32 %call, 6
+                %call10 = call i32 (ptr, ...) @printf(ptr noundef @.str.1, i32 noundef %add99)
+                ret i32 %add99
+        }
+
+        define internal i32 @_slice_add10(i32 %arg) #2 {
+            sliceclone_entry:
+                %0 = mul nsw i32 %arg, %arg
+                %1 = mul nsw i32 %0, 2
+                %2 = mul nsw i32 %1, 2
+                %3 = mul nsw i32 %2, 2
+                %4 = add nsw i32 %3, 2
+                ret i32 %4
+        }
+
+        define internal i32 @_slice_add10_alt(i32 %arg) #2 {
+            sliceclone_entry:
+                %0 = mul nsw i32 %arg, %arg
+                %1 = mul nsw i32 %0, 2
+                %2 = mul nsw i32 %1, 2
+                %3 = mul nsw i32 %2, 2
+                %4 = add nsw i32 %3, 2
+                ret i32 %4
+        }
+
+        attributes #0 = { noinline nounwind uwtable "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+        attributes #1 = { "frame-pointer"="all" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+        attributes #2 = { nounwind willreturn }
+    )invalid",
+                                                Err, Ctx));
+
+  // Expects true after merging _slice_add10 and _slice_add10_alt
+  EXPECT_TRUE(MergeFunctionsPass::runOnModule(*M));
+}
+
+TEST(MergeFunctions, TrueOutputFunctionsTest) {
+  LLVMContext Ctx;
+  SMDiagnostic Err;
+  std::unique_ptr<Module> M(parseAssemblyString(R"invalid(
+        @.str = private unnamed_addr constant [10 x i8] c"On f: %d\0A\00", align 1
+        @.str.1 = private unnamed_addr constant [13 x i8] c"On main: %d\0A\00", align 1
+
+        define dso_local i32 @f(i32 noundef %arg) #0 {
+            entry:
+                %add109 = call i32 @_slice_add10(i32 %arg)
+                %call = call i32 (ptr, ...) @printf(ptr noundef @.str, i32 noundef %add109)
+                ret i32 %add109
+        }
+
+        declare i32 @printf(ptr noundef, ...) #1
+
+        define dso_local i32 @main(i32 noundef %argc, ptr noundef %argv) #0 {
+            entry:
+                %add99 = call i32 @_slice_add10(i32 %argc)
+                %call = call i32 @f(i32 noundef 2)
+                %sub = sub nsw i32 %call, 6
+                %call10 = call i32 (ptr, ...) @printf(ptr noundef @.str.1, i32 noundef %add99)
+                ret i32 %add99
+        }
+
+        define internal i32 @_slice_add10(i32 %arg) #2 {
+            sliceclone_entry:
+                %0 = mul nsw i32 %arg, %arg
+                %1 = mul nsw i32 %0, 2
+                %2 = mul nsw i32 %1, 2
+                %3 = mul nsw i32 %2, 2
+                %4 = add nsw i32 %3, 2
+                ret i32 %4
+        }
+
+        define internal i32 @_slice_add10_alt(i32 %arg) #2 {
+            sliceclone_entry:
+                %0 = mul nsw i32 %arg, %arg
+                %1 = mul nsw i32 %0, 2
+                %2 = mul nsw i32 %1, 2
+                %3 = mul nsw i32 %2, 2
+                %4 = add nsw i32 %3, 2
+                ret i32 %4
+        }
+
+        attributes #0 = { noinline nounwind uwtable "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+        attributes #1 = { "frame-pointer"="all" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+        attributes #2 = { nounwind willreturn }
+    )invalid",
+                                                Err, Ctx));
+
+  std::set<Function *> FunctionsSet;
+  for (Function &F : *M)
+    FunctionsSet.insert(&F);
+
+  std::pair<bool, std::map<Function *, Function *>> MergeResult =
+      MergeFunctionsPass::runOnFunctions(FunctionsSet);
+
+  // Expects true after merging _slice_add10 and _slice_add10_alt
+  EXPECT_TRUE(MergeResult.first);
+
+  // Expects that both functions (_slice_add10 and _slice_add10_alt)
+  // be mapped to the same new function
+  EXPECT_TRUE(MergeResult.second.size() > 0);
+  std::map<Function *, Function *> DelToNew = MergeResult.second;
+  Function *NewFunction = M->getFunction("_slice_add10");
+  for (auto P : DelToNew)
+    if (P.second)
+      EXPECT_EQ(P.second, NewFunction);
+}
+
+TEST(MergeFunctions, FalseOutputModuleTest) {
+  LLVMContext Ctx;
+  SMDiagnostic Err;
+  std::unique_ptr<Module> M(parseAssemblyString(R"invalid(
+        @.str = private unnamed_addr constant [10 x i8] c"On f: %d\0A\00", align 1
+        @.str.1 = private unnamed_addr constant [13 x i8] c"On main: %d\0A\00", align 1
+
+        define dso_local i32 @f(i32 noundef %arg) #0 {
+            entry:
+                %add109 = call i32 @_slice_add10(i32 %arg)
+                %call = call i32 (ptr, ...) @printf(ptr noundef @.str, i32 noundef %add109)
+                ret i32 %add109
+        }
+
+        declare i32 @printf(ptr noundef, ...) #1
+
+        define dso_local i32 @main(i32 noundef %argc, ptr noundef %argv) #0 {
+            entry:
+                %add99 = call i32 @_slice_add10(i32 %argc)
+                %call = call i32 @f(i32 noundef 2)
+                %sub = sub nsw i32 %call, 6
+                %call10 = call i32 (ptr, ...) @printf(ptr noundef @.str.1, i32 noundef %add99)
+                ret i32 %add99
+        }
+
+        define internal i32 @_slice_add10(i32 %arg) #2 {
+            sliceclone_entry:
+                %0 = mul nsw i32 %arg, %arg
+                %1 = mul nsw i32 %0, 2
+                %2 = mul nsw i32 %1, 2
+                %3 = mul nsw i32 %2, 2
+                %4 = add nsw i32 %3, 2
+                ret i32 %4
+        }
+
+        define internal i32 @_slice_add10_alt(i32 %arg) #2 {
+            sliceclone_entry:
+                %0 = mul nsw i32 %arg, %arg
+                %1 = mul nsw i32 %0, 2
+                %2 = mul nsw i32 %1, 2
+                %3 = mul nsw i32 %2, 2
+                %4 = add nsw i32 %3, 2
+                ret i32 %0
+        }
+
+        attributes #0 = { noinline nounwind uwtable "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+        attributes #1 = { "frame-pointer"="all" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+        attributes #2 = { nounwind willreturn }
+    )invalid",
+                                                Err, Ctx));
+
+  // Expects false after trying to merge _slice_add10 and _slice_add10_alt
+  EXPECT_FALSE(MergeFunctionsPass::runOnModule(*M));
+}
+
+TEST(MergeFunctions, FalseOutputFunctionsTest) {
+  LLVMContext Ctx;
+  SMDiagnostic Err;
+  std::unique_ptr<Module> M(parseAssemblyString(R"invalid(
+        @.str = private unnamed_addr constant [10 x i8] c"On f: %d\0A\00", align 1
+        @.str.1 = private unnamed_addr constant [13 x i8] c"On main: %d\0A\00", align 1
+
+        define dso_local i32 @f(i32 noundef %arg) #0 {
+            entry:
+                %add109 = call i32 @_slice_add10(i32 %arg)
+                %call = call i32 (ptr, ...) @printf(ptr noundef @.str, i32 noundef %add109)
+                ret i32 %add109
+        }
+
+        declare i32 @printf(ptr noundef, ...) #1
+
+        define dso_local i32 @main(i32 noundef %argc, ptr noundef %argv) #0 {
+            entry:
+                %add99 = call i32 @_slice_add10(i32 %argc)
+                %call = call i32 @f(i32 noundef 2)
+                %sub = sub nsw i32 %call, 6
+                %call10 = call i32 (ptr, ...) @printf(ptr noundef @.str.1, i32 noundef %add99)
+                ret i32 %add99
+        }
+
+        define internal i32 @_slice_add10(i32 %arg) #2 {
+            sliceclone_entry:
+                %0 = mul nsw i32 %arg, %arg
+                %1 = mul nsw i32 %0, 2
+                %2 = mul nsw i32 %1, 2
+                %3 = mul nsw i32 %2, 2
+                %4 = add nsw i32 %3, 2
+                ret i32 %4
+        }
+
+        define internal i32 @_slice_add10_alt(i32 %arg) #2 {
+            sliceclone_entry:
+                %0 = mul nsw i32 %arg, %arg
+                %1 = mul nsw i32 %0, 2
+                %2 = mul nsw i32 %1, 2
+                %3 = mul nsw i32 %2, 2
+                %4 = add nsw i32 %3, 2
+                ret i32 %0
+        }
+
+        attributes #0 = { noinline nounwind uwtable "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+        attributes #1 = { "frame-pointer"="all" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+        attributes #2 = { nounwind willreturn }
+    )invalid",
+                                                Err, Ctx));
+
+  std::set<Function *> FunctionsSet;
+  for (Function &F : *M)
+    FunctionsSet.insert(&F);
+
+  std::pair<bool, std::map<Function *, Function *>> MergeResult =
+      MergeFunctionsPass::runOnFunctions(FunctionsSet);
+
+  for (auto P : MergeResult.second)
+    std::cout << P.first << " " << P.second << "\n";
+
+  // Expects false after trying to merge _slice_add10 and _slice_add10_alt
+  EXPECT_FALSE(MergeResult.first);
+
+  // Expects empty map
+  EXPECT_EQ(MergeResult.second.size(), 0u);
+}
+
+} // namespace
\ No newline at end of file
diff --git a/llvm/utils/gn/secondary/llvm/unittests/Transforms/Utils/BUILD.gn b/llvm/utils/gn/secondary/llvm/unittests/Transforms/Utils/BUILD.gn
index 380ed71a2bc010..fcea55c91f083c 100644
--- a/llvm/utils/gn/secondary/llvm/unittests/Transforms/Utils/BUILD.gn
+++ b/llvm/utils/gn/secondary/llvm/unittests/Transforms/Utils/BUILD.gn
@@ -27,6 +27,7 @@ unittest("UtilsTests") {
     "LoopUtilsTest.cpp",
     "MemTransferLowering.cpp",
     "ModuleUtilsTest.cpp",
+    "MergeFunctionsTest.cpp",
     "ProfDataUtilTest.cpp",
     "SSAUpdaterBulkTest.cpp",
     "ScalarEvolutionExpanderTest.cpp",

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github-actions bot commented Nov 1, 2024

⚠️ C/C++ code formatter, clang-format found issues in your code. ⚠️

You can test this locally with the following command:
git-clang-format --diff 9043bdbce4ab1c6f07e72ddfedf7165bdf2b3e40 ce17acc603d32b1033c650083f00421fea4637c1 --extensions cpp,h -- llvm/unittests/Transforms/Utils/MergeFunctionsTest.cpp llvm/include/llvm/Transforms/IPO/MergeFunctions.h llvm/lib/Transforms/IPO/MergeFunctions.cpp
View the diff from clang-format here.
diff --git a/llvm/unittests/Transforms/Utils/MergeFunctionsTest.cpp b/llvm/unittests/Transforms/Utils/MergeFunctionsTest.cpp
index 696c5391ef..2f86ec6ed7 100644
--- a/llvm/unittests/Transforms/Utils/MergeFunctionsTest.cpp
+++ b/llvm/unittests/Transforms/Utils/MergeFunctionsTest.cpp
@@ -1,5 +1,5 @@
 //===- MergeFunctionsTest.cpp - Unit tests for
-//MergeFunctionsPass-----------===//
+// MergeFunctionsPass-----------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.

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@oskarwirga @SLTozer

@@ -467,6 +484,47 @@ bool MergeFunctions::runOnModule(Module &M) {
return Changed;
}

bool MergeFunctions::runOnFunctions(std::set<Function *> &F) {
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It'd be good if this could be de-duplicated with MergeFunctions::runOnModule - the implementation looks to be identical, apart from iterating over a std::set<Function *> rather than a Module, and not having the collectUsedGlobalVariables step at the start (it's not immediately clear to me if this step would be meaningful in the runOnFunctions case.

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Resolved in 67d70af .

@@ -297,17 +300,31 @@ class MergeFunctions {
// dangling iterators into FnTree. The invariant that preserves this is that
// there is exactly one mapping F -> FN for each FunctionNode FN in FnTree.
DenseMap<AssertingVH<Function>, FnTreeType::iterator> FNodesInTree;

/// Deleted-New functions mapping
std::map<Function *, Function *> DelToNewMap;
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This (and probably other maps here) could be a DenseMap instead, unless there's a reason this needs std::map. I think it could also be a returned value from runOnFunctions rather than a member, but that's mostly subjective.

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Resolved in 67d70af .

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A few more comments - structurally this looks fine, just have some code suggestions/questions.

Comment on lines 1 to 2
//===- MergeFunctionsTest.cpp - Unit tests for
// MergeFunctionsPass-----------===//
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Nit, this should all be on one line.

Suggested change
//===- MergeFunctionsTest.cpp - Unit tests for
// MergeFunctionsPass-----------===//
//===- MergeFunctionsTest.cpp - Unit tests for MergeFunctionsPass ---------===//

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Resolved in eae748a.

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clang format keeps changing that to two lines: 1fdf94e.

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Clang-format will format to a max column with of 80 - for the file header comments, you should change the padding hyphens so that it's exactly 80 characters wide (example in the github suggestion).

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Oosp, my bad. Fixed it! d193a63

Comment on lines 435 to 440
if constexpr (std::is_same<FuncContainer, Module>::value) {
SmallVector<GlobalValue *, 4> UsedV;
collectUsedGlobalVariables(M, UsedV, /*CompilerUsed=*/false);
collectUsedGlobalVariables(M, UsedV, /*CompilerUsed=*/true);
Used.insert(UsedV.begin(), UsedV.end());
}
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Since this runs at the top of the function and is only being used for the module case, which is only called from run, this could be moved into run before the call to runOnModule.

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Resolved in eae748a.

Comment on lines 445 to 456
if constexpr (std::is_same<FuncContainer, std::set<Function *>>::value) {
for (Function *Func : M) {
if (isEligibleForMerging(*Func)) {
HashedFuncs.push_back({StructuralHash(*Func), Func});
}
}
}
if constexpr (std::is_same<FuncContainer, Module>::value) {
for (Function &Func : M) {
if (isEligibleForMerging(Func)) {
HashedFuncs.push_back({StructuralHash(Func), &Func});
}
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Small suggestion, but this could be further simplified (and made less dependent on the exact types passed into it) by using one loop with an auto type and extracting a Function* from that. In particular, right now if the user changed the variable type being passed in from std::set to llvm::DenseSet or some similar change, this function would successfully compile but neither of these blocks would be entered. I think the simplest way would be to create a pair of functions above this one:

  inline Function *asPtr(Function *Fn) { return Fn; }
  inline Function *asPtr(Function &Fn) { return &Fn; }
...
  for (auto Func : M) {
    Function *FuncPtr = asPtr(Func);

Or, you could do it inline with if constexpr:

  Function *FuncPtr;
  if constexpr (std::is_reference_type_v<decltype(Func)>)
    FuncPtr = &Func;
  else
    FuncPtr = Func;

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Resolved in eae748a.

@@ -409,24 +428,36 @@ static bool isEligibleForMerging(Function &F) {
!hasDistinctMetadataIntrinsic(F);
}

bool MergeFunctions::runOnModule(Module &M) {
template <typename FuncContainer>
bool MergeFunctions::runOnModule(FuncContainer &M) {
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The name should probably change since it now takes different types.

Suggested change
bool MergeFunctions::runOnModule(FuncContainer &M) {
bool MergeFunctions::run(FuncContainer &M) {

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Resolved in eae748a.

}
}

llvm::stable_sort(HashedFuncs, less_first());
stable_sort(HashedFuncs, less_first());
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Is there a reason for removing the llvm:: namespace qualifiers here and elsewhere in this file?

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Resolved in eae748a.

Comment on lines 122 to 124
attributes #0 = { noinline nounwind uwtable "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
attributes #1 = { "frame-pointer"="all" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
attributes #2 = { nounwind willreturn }
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Any of these attributes that aren't needed for the test could be deleted (and the same for all subsequent tests).

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Resolved in eae748a.

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3 participants