[llvm] Revert "[PowerPC] Add custom lowering for ssubo (#111748)" (PR #114672)

[Maryam Moghadas via llvm-commits]

https://github.com/maryammo created https://github.com/llvm/llvm-project/pull/114672

This reverts commit 8a0cb9ac869334fd6c6bd6aad8408623a7ccd7f6.
Reverting due to PPC bootstrap bot failure.



>From 0de8d2b5c89b090abe084ddd7d8bb13d6b659b5f Mon Sep 17 00:00:00 2001
From: Maryam Moghadas <maryammo at cpap8102.rtp.raleigh.ibm.com>
Date: Sat, 2 Nov 2024 10:05:05 -0400
Subject: [PATCH] Revert "[PowerPC] Add custom lowering for ssubo (#111748)"

This reverts commit 8a0cb9ac869334fd6c6bd6aad8408623a7ccd7f6.
---
 llvm/lib/Target/PowerPC/PPCISelLowering.cpp | 37 ---------------------
 llvm/lib/Target/PowerPC/PPCISelLowering.h   |  1 -
 llvm/test/CodeGen/PowerPC/saddo-ssubo.ll    | 11 +++---
 3 files changed, 6 insertions(+), 43 deletions(-)

diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index d8f3095ed7fb68..ab31898e262e7e 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -200,11 +200,6 @@ PPCTargetLowering::PPCTargetLowering(const PPCTargetMachine &TM,
 
   setOperationAction(ISD::UADDO, isPPC64 ? MVT::i64 : MVT::i32, Custom);
 
-  // On P10, the default lowering generates better code using the
-  // setbc instruction.
-  if (!Subtarget.hasP10Vector() && isPPC64)
-    setOperationAction(ISD::SSUBO, MVT::i32, Custom);
-
   // Match BITREVERSE to customized fast code sequence in the td file.
   setOperationAction(ISD::BITREVERSE, MVT::i32, Legal);
   setOperationAction(ISD::BITREVERSE, MVT::i64, Legal);
@@ -12021,36 +12016,6 @@ SDValue PPCTargetLowering::LowerUaddo(SDValue Op, SelectionDAG &DAG) const {
   return Res;
 }
 
-SDValue PPCTargetLowering::LowerSSUBO(SDValue Op, SelectionDAG &DAG) const {
-
-  SDLoc dl(Op);
-
-  SDValue LHS64 = DAG.getNode(ISD::ANY_EXTEND, dl, MVT::i64, Op.getOperand(0));
-  SDValue RHS64 = DAG.getNode(ISD::ANY_EXTEND, dl, MVT::i64, Op.getOperand(1));
-
-  SDValue Sub = DAG.getNode(ISD::SUB, dl, MVT::i64, LHS64, RHS64);
-
-  SDValue Extsw = DAG.getNode(ISD::SIGN_EXTEND_INREG, dl, MVT::i64, Sub,
-                              DAG.getValueType(MVT::i32));
-
-  SDValue Xor = DAG.getNode(ISD::XOR, dl, MVT::i64, Extsw, Sub);
-
-  SDValue Addic = DAG.getNode(ISD::ADDC, dl, DAG.getVTList(MVT::i64, MVT::Glue),
-                              Xor, DAG.getConstant(-1, dl, MVT::i64));
-
-  SDValue Overflow =
-      DAG.getNode(ISD::SUBE, dl, DAG.getVTList(MVT::i64, MVT::Glue), Xor, Addic,
-                  Addic.getValue(1));
-
-  SDValue OverflowTrunc =
-      DAG.getNode(ISD::TRUNCATE, dl, Op.getNode()->getValueType(1), Overflow);
-  SDValue SubTrunc =
-      (Sub->getValueType(0) != Op.getNode()->getValueType(0))
-          ? DAG.getNode(ISD::TRUNCATE, dl, Op.getNode()->getValueType(0), Sub)
-          : Sub;
-  return DAG.getMergeValues({SubTrunc, OverflowTrunc}, dl);
-}
-
 /// LowerOperation - Provide custom lowering hooks for some operations.
 ///
 SDValue PPCTargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const {
@@ -12073,8 +12038,6 @@ SDValue PPCTargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const {
   case ISD::SETCC:              return LowerSETCC(Op, DAG);
   case ISD::INIT_TRAMPOLINE:    return LowerINIT_TRAMPOLINE(Op, DAG);
   case ISD::ADJUST_TRAMPOLINE:  return LowerADJUST_TRAMPOLINE(Op, DAG);
-  case ISD::SSUBO:
-    return LowerSSUBO(Op, DAG);
 
   case ISD::INLINEASM:
   case ISD::INLINEASM_BR:       return LowerINLINEASM(Op, DAG);
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.h b/llvm/lib/Target/PowerPC/PPCISelLowering.h
index dde45e4cf6f4ae..0adbad86845973 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.h
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.h
@@ -1279,7 +1279,6 @@ namespace llvm {
     SDValue LowerJumpTable(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerUaddo(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerSETCC(SDValue Op, SelectionDAG &DAG) const;
-    SDValue LowerSSUBO(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerINIT_TRAMPOLINE(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerADJUST_TRAMPOLINE(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerINLINEASM(SDValue Op, SelectionDAG &DAG) const;
diff --git a/llvm/test/CodeGen/PowerPC/saddo-ssubo.ll b/llvm/test/CodeGen/PowerPC/saddo-ssubo.ll
index 7147257d27c4b8..fd5f26ba35742f 100644
--- a/llvm/test/CodeGen/PowerPC/saddo-ssubo.ll
+++ b/llvm/test/CodeGen/PowerPC/saddo-ssubo.ll
@@ -129,11 +129,12 @@ entry:
 define i1 @test_ssubo_i32(i32 %a, i32 %b) nounwind {
 ; CHECK-LABEL: test_ssubo_i32:
 ; CHECK:       # %bb.0: # %entry
-; CHECK-NEXT:    sub 3, 3, 4
-; CHECK-NEXT:    extsw 4, 3
-; CHECK-NEXT:    xor 3, 4, 3
-; CHECK-NEXT:    addic 4, 3, -1
-; CHECK-NEXT:    subfe 3, 4, 3
+; CHECK-NEXT:    sub 5, 3, 4
+; CHECK-NEXT:    cmpwi 1, 4, 0
+; CHECK-NEXT:    cmpw 5, 3
+; CHECK-NEXT:    li 3, 1
+; CHECK-NEXT:    creqv 20, 5, 0
+; CHECK-NEXT:    isel 3, 0, 3, 20
 ; CHECK-NEXT:    blr
 entry:
   %res = call { i32, i1 } @llvm.ssub.with.overflow.i32(i32 %a, i32 %b) nounwind