Move the Swift function-merging pass to LLVM

include/llvm/InitializePasses.h

@@ -272,6 +272,7 @@ void initializeMemorySSAPrinterLegacyPassPass(PassRegistry&);
 void initializeMemorySSAWrapperPassPass(PassRegistry&);
 void initializeMemorySanitizerPass(PassRegistry&);
 void initializeMergeFunctionsPass(PassRegistry&);
+void initializeMergeSimilarFunctionsPass(PassRegistry &);
 void initializeMergeICmpsPass(PassRegistry&);
 void initializeMergedLoadStoreMotionLegacyPassPass(PassRegistry&);
 void initializeMetaRenamerPass(PassRegistry&);

include/llvm/LinkAllPasses.h

@@ -189,6 +189,7 @@ namespace {
       (void) llvm::createPostOrderFunctionAttrsLegacyPass();
       (void) llvm::createReversePostOrderFunctionAttrsPass();
       (void) llvm::createMergeFunctionsPass();
+      (void)llvm::createMergeSimilarFunctionsPass();
       (void) llvm::createMergeICmpsPass();
       (void) llvm::createExpandMemCmpPass();
       std::string buf;

include/llvm/Transforms/IPO.h

@@ -201,6 +201,12 @@ Pass *createReversePostOrderFunctionAttrsPass();
 ///
 ModulePass *createMergeFunctionsPass();
 
+//===----------------------------------------------------------------------===//
+/// createMergeSimilarFunctionsPass - This pass discovers similar functions and
+/// collapses them.
+///
+ModulePass *createMergeSimilarFunctionsPass();
+
 //===----------------------------------------------------------------------===//
 /// createHotColdSplittingPass - This pass outlines cold blocks into a separate
 /// function(s).

include/llvm/Transforms/IPO/PassManagerBuilder.h

@@ -153,6 +153,7 @@ class PassManagerBuilder {
   bool VerifyInput;
   bool VerifyOutput;
   bool MergeFunctions;
+  bool MergeSimilarFunctions;
   bool PrepareForLTO;
   bool PrepareForThinLTO;
   bool PerformThinLTO;

lib/Transforms/IPO/CMakeLists.txt

@@ -25,6 +25,7 @@ add_llvm_library(LLVMipo
   LoopExtractor.cpp
   LowerTypeTests.cpp
   MergeFunctions.cpp
+  MergeSimilarFunctions.cpp
   PartialInlining.cpp
   PassManagerBuilder.cpp
   PruneEH.cpp

lib/Transforms/IPO/IPO.cpp

@@ -45,6 +45,7 @@ void llvm::initializeIPO(PassRegistry &Registry) {
   initializeSingleLoopExtractorPass(Registry);
   initializeLowerTypeTestsPass(Registry);
   initializeMergeFunctionsPass(Registry);
+  initializeMergeSimilarFunctionsPass(Registry);
   initializePartialInlinerLegacyPassPass(Registry);
   initializePostOrderFunctionAttrsLegacyPassPass(Registry);
   initializeReversePostOrderFunctionAttrsLegacyPassPass(Registry);

lib/Transforms/IPO/PassManagerBuilder.cpp

@@ -170,6 +170,7 @@ PassManagerBuilder::PassManagerBuilder() {
     VerifyInput = false;
     VerifyOutput = false;
     MergeFunctions = false;
+    MergeSimilarFunctions = false;
     PrepareForLTO = false;
     EnablePGOInstrGen = RunPGOInstrGen;
     PGOInstrGen = PGOOutputFile;
@@ -446,6 +447,9 @@ void PassManagerBuilder::populateModulePassManager(
     else if (GlobalExtensionsNotEmpty() || !Extensions.empty())
       MPM.add(createBarrierNoopPass());
 
+    if (MergeSimilarFunctions)
+      MPM.add(createMergeSimilarFunctionsPass());
+
     if (PerformThinLTO) {
       // Drop available_externally and unreferenced globals. This is necessary
       // with ThinLTO in order to avoid leaving undefined references to dead
@@ -713,6 +717,9 @@ void PassManagerBuilder::populateModulePassManager(
   if (MergeFunctions)
     MPM.add(createMergeFunctionsPass());
 
+  if (MergeSimilarFunctions)
+    MPM.add(createMergeSimilarFunctionsPass());
+
   // LoopSink pass sinks instructions hoisted by LICM, which serves as a
   // canonicalization pass that enables other optimizations. As a result,
   // LoopSink pass needs to be a very late IR pass to avoid undoing LICM
@@ -905,6 +912,9 @@ void PassManagerBuilder::addLateLTOOptimizationPasses(
   // currently it damages debug info.
   if (MergeFunctions)
     PM.add(createMergeFunctionsPass());
+
+  if (MergeSimilarFunctions)
+    PM.add(createMergeSimilarFunctionsPass());
 }
 
 void PassManagerBuilder::populateThinLTOPassManager(

test/Transforms/MergeFunc/merge_similar_func_coff.ll

@@ -0,0 +1,23 @@
+; RUN: opt -S -mtriple i686-windows -merge-similar-functions -mergesimfunc-threshold=4 %s | FileCheck %s
+
+@g = external global i32
+
+define dllexport i32 @f(i32 %x, i32 %y) {
+  %sum = add i32 %x, %y
+  %sum2 = add i32 %sum, %y
+  %l = load i32, i32* @g, align 4
+  %sum3 = add i32 %sum2, %y
+  ret i32 %sum3
+}
+
+define dllexport i32 @h(i32 %x, i32 %y) {
+  %sum = add i32 %x, %y
+  %sum2 = add i32 %sum, %y
+  %l = load i32, i32* @g, align 4
+  %sum3 = add i32 %sum2, %y
+  ret i32 %sum3
+}
+
+; CHECK-NOT: define internal dllexport i32 @fTm(i32, i32)
+; CHECK-LABEL: define internal i32 @fTm(i32, i32)
+