[MacroFusion] Remove createBranchMacroFusionDAGMutation (#76209)

Instead, we add a `BranchOnly` parameter to indicate that only
branches with its predecessors will be fused.

X86 is the only user of `createBranchMacroFusionDAGMutation`.

Author: wangpc-pp

llvm/include/llvm/CodeGen/MacroFusion.h

@@ -50,15 +50,11 @@ bool fuseInstructionPair(ScheduleDAGInstrs &DAG, SUnit &FirstSU,
 /// for instructions that benefit according to the target-specific
 /// predicate functions. shouldScheduleAdjacent will be true if any of the
 /// provided predicates are true.
+/// If BranchOnly is true, only branch instructions with one of their
+/// predecessors will be fused.
 std::unique_ptr<ScheduleDAGMutation>
-createMacroFusionDAGMutation(ArrayRef<MacroFusionPredTy> Predicates);
-
-/// Create a DAG scheduling mutation to pair branch instructions with one
-/// of their predecessors back to back for instructions that benefit according
-/// to the target-specific predicate functions. shouldScheduleAdjacent will be
-/// true if any of the provided predicates are true.
-std::unique_ptr<ScheduleDAGMutation>
-createBranchMacroFusionDAGMutation(ArrayRef<MacroFusionPredTy> Predicates);
+createMacroFusionDAGMutation(ArrayRef<MacroFusionPredTy> Predicates,
+                             bool BranchOnly = false);
 
 } // end namespace llvm
 

llvm/lib/CodeGen/MacroFusion.cpp

@@ -212,15 +212,9 @@ bool MacroFusion::scheduleAdjacentImpl(ScheduleDAGInstrs &DAG, SUnit &AnchorSU)
 }
 
 std::unique_ptr<ScheduleDAGMutation>
-llvm::createMacroFusionDAGMutation(ArrayRef<MacroFusionPredTy> Predicates) {
+llvm::createMacroFusionDAGMutation(ArrayRef<MacroFusionPredTy> Predicates,
+                                   bool BranchOnly) {
   if (EnableMacroFusion)
-    return std::make_unique<MacroFusion>(Predicates, true);
-  return nullptr;
-}
-
-std::unique_ptr<ScheduleDAGMutation> llvm::createBranchMacroFusionDAGMutation(
-    ArrayRef<MacroFusionPredTy> Predicates) {
-  if (EnableMacroFusion)
-    return std::make_unique<MacroFusion>(Predicates, false);
+    return std::make_unique<MacroFusion>(Predicates, !BranchOnly);
   return nullptr;
 }

llvm/lib/Target/X86/X86MacroFusion.cpp

@@ -68,7 +68,8 @@ static bool shouldScheduleAdjacent(const TargetInstrInfo &TII,
 namespace llvm {
 
 std::unique_ptr<ScheduleDAGMutation> createX86MacroFusionDAGMutation() {
-  return createBranchMacroFusionDAGMutation(shouldScheduleAdjacent);
+  return createMacroFusionDAGMutation(shouldScheduleAdjacent,
+                                      /*BranchOnly=*/true);
 }
 
 } // end namespace llvm