Revert "Port Swift's merge function pass to llvm: merging functions that differ in constants (#68235)"

This reverts commit 19b5495.

PR landed without approval, with severe quality issues.

Author: nikic

llvm/include/llvm/Transforms/IPO/MergeFunctionsIgnoringConst.h

@@ -379,7 +379,6 @@ class FunctionComparator {
   /// But, we are still not able to compare operands of PHI nodes, since those
   /// could be operands from further BBs we didn't scan yet.
   /// So it's impossible to use dominance properties in general.
-protected:
   mutable DenseMap<const Value*, int> sn_mapL, sn_mapR;
 
   // The global state we will use

llvm/include/llvm/Transforms/Utils/FunctionComparator.h

@@ -123,7 +123,6 @@
 #include "llvm/Transforms/IPO/LowerTypeTests.h"
 #include "llvm/Transforms/IPO/MemProfContextDisambiguation.h"
 #include "llvm/Transforms/IPO/MergeFunctions.h"
-#include "llvm/Transforms/IPO/MergeFunctionsIgnoringConst.h"
 #include "llvm/Transforms/IPO/ModuleInliner.h"
 #include "llvm/Transforms/IPO/OpenMPOpt.h"
 #include "llvm/Transforms/IPO/PartialInlining.h"

llvm/include/llvm/Transforms/Utils/FunctionComparatorIgnoringConst.h

@@ -60,7 +60,6 @@
 #include "llvm/Transforms/IPO/LowerTypeTests.h"
 #include "llvm/Transforms/IPO/MemProfContextDisambiguation.h"
 #include "llvm/Transforms/IPO/MergeFunctions.h"
-#include "llvm/Transforms/IPO/MergeFunctionsIgnoringConst.h"
 #include "llvm/Transforms/IPO/ModuleInliner.h"
 #include "llvm/Transforms/IPO/OpenMPOpt.h"
 #include "llvm/Transforms/IPO/PartialInlining.h"
@@ -177,10 +176,6 @@ static cl::opt<bool> EnableMergeFunctions(
     "enable-merge-functions", cl::init(false), cl::Hidden,
     cl::desc("Enable function merging as part of the optimization pipeline"));
 
-static cl::opt<bool> EnableMergeFuncIgnoringConst(
-    "enable-merge-func-ignoring-const", cl::init(false), cl::Hidden,
-    cl::desc("Enable function merger that ignores constants"));
-
 static cl::opt<bool> EnablePostPGOLoopRotation(
     "enable-post-pgo-loop-rotation", cl::init(true), cl::Hidden,
     cl::desc("Run the loop rotation transformation after PGO instrumentation"));
@@ -1638,9 +1633,6 @@ ModulePassManager PassBuilder::buildThinLTODefaultPipeline(
   MPM.addPass(buildModuleOptimizationPipeline(
       Level, ThinOrFullLTOPhase::ThinLTOPostLink));
 
-  if (EnableMergeFuncIgnoringConst)
-    MPM.addPass(MergeFuncIgnoringConstPass());
-
   // Emit annotation remarks.
   addAnnotationRemarksPass(MPM);
 
@@ -1966,9 +1958,6 @@ PassBuilder::buildLTODefaultPipeline(OptimizationLevel Level,
 
   invokeFullLinkTimeOptimizationLastEPCallbacks(MPM, Level);
 
-  if (EnableMergeFuncIgnoringConst)
-    MPM.addPass(MergeFuncIgnoringConstPass());
-
   // Emit annotation remarks.
   addAnnotationRemarksPass(MPM);
 

llvm/include/llvm/Transforms/Utils/MergeFunctionsIgnoringConst.h

@@ -87,7 +87,6 @@ MODULE_PASS("lower-ifunc", LowerIFuncPass())
 MODULE_PASS("lowertypetests", LowerTypeTestsPass())
 MODULE_PASS("metarenamer", MetaRenamerPass())
 MODULE_PASS("mergefunc", MergeFunctionsPass())
-MODULE_PASS("mergefunc-ignoring-const", MergeFuncIgnoringConstPass())
 MODULE_PASS("name-anon-globals", NameAnonGlobalPass())
 MODULE_PASS("no-op-module", NoOpModulePass())
 MODULE_PASS("objc-arc-apelim", ObjCARCAPElimPass())

llvm/lib/Passes/PassBuilder.cpp

@@ -30,7 +30,6 @@ add_llvm_component_library(LLVMipo
   LowerTypeTests.cpp
   MemProfContextDisambiguation.cpp
   MergeFunctions.cpp
-  MergeFunctionsIgnoringConst.cpp
   ModuleInliner.cpp
   OpenMPOpt.cpp
   PartialInlining.cpp