[PowerPC] [Peephole] fold frame offset by using index form to save add.

renamable $x6 = ADDI8 $x1, -80      ;;; 0 is replaced with -80
renamable $x6 = ADD8 killed renamable $x6, renamable $x5
STW killed renamable $r3, 4, killed renamable $x6 :: (store 4 into %ir.14, !tbaa !2)

After PEI there is a peephole opt opportunity to combine above -80 in ADDI8 with 4 in the STW to eliminate unnecessary ADD8.

Expected result:
renamable $x6 = ADDI8 $x1, -76
STWX killed renamable $r3, renamable $x5, killed renamable $x6 :: (store 4 into %ir.6, !tbaa !2)

Reviewed by: stefanp

Differential Revision: https://reviews.llvm.org/D66329

1 files changed, 10 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.h b/llvm/lib/Target/PowerPC/PPCInstrInfo.h
index 19ab30cb090..d76809027f8 100644
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.h
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.h
@@ -422,6 +422,16 @@ public:
 
   bool convertToImmediateForm(MachineInstr &MI,
                               MachineInstr **KilledDef = nullptr) const;
+  bool foldFrameOffset(MachineInstr &MI) const;
+  bool isADDIInstrEligibleForFolding(MachineInstr &ADDIMI, int64_t &Imm) const;
+  bool isADDInstrEligibleForFolding(MachineInstr &ADDMI) const;
+  bool isImmInstrEligibleForFolding(MachineInstr &MI, unsigned &BaseReg,
+                                    unsigned &XFormOpcode,
+                                    int64_t &OffsetOfImmInstr,
+                                    ImmInstrInfo &III) const;
+  bool isValidToBeChangedReg(MachineInstr *ADDMI, unsigned Index,
+                             MachineInstr *&ADDIMI, int64_t &OffsetAddi,
+                             int64_t OffsetImm) const;
 
   /// Fixup killed/dead flag for register \p RegNo between instructions [\p
   /// StartMI, \p EndMI]. Some PostRA transformations may violate register