[CodeGen][NPM] Create method to add the branch folding pass with the option to enable tail merge

Signed-off-by: Mikhail R. Gadelha <[email protected]>

Author: mikhailramalho

llvm/include/llvm/CodeGen/Passes.h

@@ -257,6 +257,8 @@ namespace llvm {
   /// branches.
   extern char &BranchFolderPassID;
 
+  MachineFunctionPass *createBranchFolderPass(bool EnableTailMerge);
+
   /// BranchRelaxation - This pass replaces branches that need to jump further
   /// than is supported by a branch instruction.
   extern char &BranchRelaxationPassID;

llvm/lib/CodeGen/BranchFolding.cpp

@@ -90,10 +90,13 @@ namespace {
 
   /// BranchFolderPass - Wrap branch folder in a machine function pass.
 class BranchFolderLegacy : public MachineFunctionPass {
+  bool EnableTailMerge;
+
 public:
   static char ID;
 
-  explicit BranchFolderLegacy() : MachineFunctionPass(ID) {}
+  explicit BranchFolderLegacy(bool EnableTailMerge = true)
+      : MachineFunctionPass(ID), EnableTailMerge(EnableTailMerge) {}
 
   bool runOnMachineFunction(MachineFunction &MF) override;
 
@@ -152,7 +155,8 @@ bool BranchFolderLegacy::runOnMachineFunction(MachineFunction &MF) {
   // TailMerge can create jump into if branches that make CFG irreducible for
   // HW that requires structurized CFG.
   bool EnableTailMerge = !MF.getTarget().requiresStructuredCFG() &&
-                         PassConfig->getEnableTailMerge();
+                         PassConfig->getEnableTailMerge() &&
+                         this->EnableTailMerge;
   MBFIWrapper MBBFreqInfo(
       getAnalysis<MachineBlockFrequencyInfoWrapperPass>().getMBFI());
   BranchFolder Folder(
@@ -2080,3 +2084,7 @@ bool BranchFolder::HoistCommonCodeInSuccs(MachineBasicBlock *MBB) {
   ++NumHoist;
   return true;
 }
+
+MachineFunctionPass *llvm::createBranchFolderPass(bool EnableTailMerge = true) {
+  return new BranchFolderLegacy(EnableTailMerge);
+}

llvm/lib/Target/RISCV/RISCVTargetMachine.cpp

@@ -18,6 +18,7 @@
 #include "RISCVTargetTransformInfo.h"
 #include "TargetInfo/RISCVTargetInfo.h"
 #include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/CodeGen/BranchFoldingPass.h"
 #include "llvm/CodeGen/GlobalISel/CSEInfo.h"
 #include "llvm/CodeGen/GlobalISel/IRTranslator.h"
 #include "llvm/CodeGen/GlobalISel/InstructionSelect.h"