[AArch64] Move CSEL a, b, cc, SUBS(SUB(x,y), 0) -> CSEL a, b, cc, SUBS(x,y) to peephole by adding the missing sForms

[AZero13]

Peephole should be doing this, not DAG.

[llvmbot]

@llvm/pr-subscribers-backend-aarch64

Author: AZero13 (AZero13)

Changes

The goal is to eventually remove the CSEL a, b, cc, SUBS(SUB(x,y), 0) -> CSEL a, b, cc, SUBS(x,y) transform because peephole should have been doing it, but it has not this whole time. midpoint-int has a regression so the transform itself is not removed yet. That will come in another PR.

---

Full diff: https://github.com/llvm/llvm-project/pull/157552.diff

1 Files Affected:

• (modified) llvm/lib/Target/AArch64/AArch64InstrInfo.cpp (+16)

diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
index 3ce7829207cb6..0181a70f773f1 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -1718,12 +1718,20 @@ static unsigned sForm(MachineInstr &Instr) {
 
   case AArch64::ADDSWrr:
   case AArch64::ADDSWri:
+  case AArch64::ADDSWrx:
   case AArch64::ADDSXrr:
   case AArch64::ADDSXri:
+  case AArch64::ADDSXrx:
   case AArch64::SUBSWrr:
   case AArch64::SUBSWri:
+  case AArch64::SUBSWrx:
   case AArch64::SUBSXrr:
   case AArch64::SUBSXri:
+  case AArch64::SUBSXrx:
+  case AArch64::ADCSWr:
+  case AArch64::ADCSXr:
+  case AArch64::SBCSWr:
+  case AArch64::SBCSXr:
     return Instr.getOpcode();
 
   case AArch64::ADDWrr:
@@ -1734,6 +1742,10 @@ static unsigned sForm(MachineInstr &Instr) {
     return AArch64::ADDSXrr;
   case AArch64::ADDXri:
     return AArch64::ADDSXri;
+  case AArch64::ADDWrx:
+    return AArch64::ADDSWrx;
+  case AArch64::ADDXrx:
+    return AArch64::ADDSXrx;
   case AArch64::ADCWr:
     return AArch64::ADCSWr;
   case AArch64::ADCXr:
@@ -1746,6 +1758,10 @@ static unsigned sForm(MachineInstr &Instr) {
     return AArch64::SUBSXrr;
   case AArch64::SUBXri:
     return AArch64::SUBSXri;
+  case AArch64::SUBWrx:
+    return AArch64::SUBSWrx;
+  case AArch64::SUBXrx:
+    return AArch64::SUBSXrx;
   case AArch64::SBCWr:
     return AArch64::SBCSWr;
   case AArch64::SBCXr:

[AZero13]

This is kinda messy but I want to know what @davemgreen thinks