[GlobalISel] Make more use of replaceSingleDefInstWithReg. NFC.

Author: jayfoad

llvm/include/llvm/Target/GlobalISel/Combine.td

@@ -424,7 +424,7 @@ def anyext_trunc_fold: GICombineRule <
   (defs root:$root, anyext_trunc_fold_matchinfo:$matchinfo),
   (match (wip_match_opcode G_ANYEXT):$root,
          [{ return Helper.matchCombineAnyExtTrunc(*${root}, ${matchinfo}); }]),
-  (apply [{ return Helper.applyCombineAnyExtTrunc(*${root}, ${matchinfo}); }])
+  (apply [{ return Helper.replaceSingleDefInstWithReg(*${root}, ${matchinfo}); }])
 >;
 
 // Fold ([asz]ext ([asz]ext x)) -> ([asz]ext x).
@@ -468,7 +468,7 @@ def fabs_fabs_fold: GICombineRule<
   (defs root:$root, fabs_fabs_fold_matchinfo:$matchinfo),
   (match (wip_match_opcode G_FABS):$root,
          [{ return Helper.matchCombineFAbsOfFAbs(*${root}, ${matchinfo}); }]),
-  (apply [{ return Helper.applyCombineFAbsOfFAbs(*${root}, ${matchinfo}); }])
+  (apply [{ return Helper.replaceSingleDefInstWithReg(*${root}, ${matchinfo}); }])
 >;
 
 // Fold (unmerge cst) -> cst1, cst2, ...

llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp

@@ -2295,14 +2295,6 @@ bool CombinerHelper::matchCombineAnyExtTrunc(MachineInstr &MI, Register &Reg) {
                   m_GTrunc(m_all_of(m_Reg(Reg), m_SpecificType(DstTy))));
 }
 
-bool CombinerHelper::applyCombineAnyExtTrunc(MachineInstr &MI, Register &Reg) {
-  assert(MI.getOpcode() == TargetOpcode::G_ANYEXT && "Expected a G_ANYEXT");
-  Register DstReg = MI.getOperand(0).getReg();
-  MI.eraseFromParent();
-  replaceRegWith(MRI, DstReg, Reg);
-  return true;
-}
-
 bool CombinerHelper::matchCombineExtOfExt(
     MachineInstr &MI, std::tuple<Register, unsigned> &MatchInfo) {
   assert((MI.getOpcode() == TargetOpcode::G_ANYEXT ||
@@ -2384,14 +2376,6 @@ bool CombinerHelper::matchCombineFAbsOfFAbs(MachineInstr &MI, Register &Src) {
   return mi_match(Src, MRI, m_GFabs(m_Reg(AbsSrc)));
 }
 
-bool CombinerHelper::applyCombineFAbsOfFAbs(MachineInstr &MI, Register &Src) {
-  assert(MI.getOpcode() == TargetOpcode::G_FABS && "Expected a G_FABS");
-  Register Dst = MI.getOperand(0).getReg();
-  MI.eraseFromParent();
-  replaceRegWith(MRI, Dst, Src);
-  return true;
-}
-
 bool CombinerHelper::matchCombineTruncOfExt(
     MachineInstr &MI, std::pair<Register, unsigned> &MatchInfo) {
   assert(MI.getOpcode() == TargetOpcode::G_TRUNC && "Expected a G_TRUNC");