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[PowerPC]Avoid combine to ADDC i8 or ADDC i16 for PPCTargetLowering::combineSignExtendSetCC#199733

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[PowerPC]Avoid combine to ADDC i8 or ADDC i16 for PPCTargetLowering::combineSignExtendSetCC#199733
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since ADDC only support 32bit and 64bit operand

the patch avoid combine

t13: i8,ch = load<(load (s8) from %ir.cond.i.i.i29.sroa.sel.sroa.sel.sroa.sel.sroa.sel, !tbaa <0x1112348b8>)> t0, t10, undef:i32
t16: i1 = setcc t13, Constant:i8<0>, seteq:ch
t17: i32 = sign_extend t16

to

t13: i8,ch = load<(load (s8) from %ir.cond.i.i.i29.sroa.sel.sroa.sel.sroa.sel.sroa.sel, !tbaa !8)> t0, t10, undef:i32
t22: i32,i32 = PPCISD::ADDC t13, Constant:i32<-1>

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Author: zhijian lin (diggerlin)

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since ADDC only support 32bit and 64bit operand

the patch avoid combine

t13: i8,ch = load<(load (s8) from %ir.cond.i.i.i29.sroa.sel.sroa.sel.sroa.sel.sroa.sel, !tbaa <0x1112348b8>)> t0, t10, undef:i32
t16: i1 = setcc t13, Constant:i8<0>, seteq:ch
t17: i32 = sign_extend t16

to

t13: i8,ch = load<(load (s8) from %ir.cond.i.i.i29.sroa.sel.sroa.sel.sroa.sel.sroa.sel, !tbaa !8)> t0, t10, undef:i32
t22: i32,i32 = PPCISD::ADDC t13, Constant:i32<-1>


Full diff: https://github.com/llvm/llvm-project/pull/199733.diff

5 Files Affected:

  • (modified) llvm/lib/Target/PowerPC/PPCISelLowering.cpp (+8-3)
  • (modified) llvm/test/CodeGen/PowerPC/testComparesieqsc.ll (+2-2)
  • (modified) llvm/test/CodeGen/PowerPC/testComparesieqss.ll (+2-2)
  • (modified) llvm/test/CodeGen/PowerPC/testCompareslleqsc.ll (+2-2)
  • (modified) llvm/test/CodeGen/PowerPC/testCompareslleqss.ll (+2-2)
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 407093fd2b849..754b04e8c1049 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -15873,7 +15873,7 @@ SDValue PPCTargetLowering::combineSignExtendSetCC(SDNode *N,
     return SDValue();
 
   SDValue N0 = N->getOperand(0);
-  if (N0.getOpcode() != ISD::SETCC)
+  if (N0.getOpcode() != ISD::SETCC || !N0.hasOneUse())
     return SDValue();
 
   ISD::CondCode CC = cast<CondCodeSDNode>(N0.getOperand(2))->get();
@@ -15889,16 +15889,21 @@ SDValue PPCTargetLowering::combineSignExtendSetCC(SDNode *N,
   SDValue X = isNullConstant(LHS) ? RHS : LHS;
   EVT XVT = X.getValueType(); // The type of x in the setcc x, 0, eq.
 
+  if (XVT != MVT::i32 && XVT != MVT::i64)
+    return SDValue();
+
   if ((XVT == MVT::i64 || VT == MVT::i64) && !Subtarget.isPPC64())
     return SDValue();
 
   // On PPC64, i32 carry operations use the full 64-bit XER register,
   // so we must use i64 operations to avoid incorrect results.
   // Use i64 operations and truncate the result if needed.
-  if (XVT != MVT::i64 && Subtarget.isPPC64())
+  if (XVT != MVT::i64 && Subtarget.isPPC64()) {
+    if (!X.hasOneUse())
+      return SDValue();
     // Zero-extend if input type is not 64bits.
     X = DAG.getNode(ISD::ZERO_EXTEND, dl, MVT::i64, X);
-
+  }
   EVT OpVT = Subtarget.isPPC64() ? MVT::i64 : MVT::i32;
 
   // Generate: SUBFE(ADDC(X, -1)).
diff --git a/llvm/test/CodeGen/PowerPC/testComparesieqsc.ll b/llvm/test/CodeGen/PowerPC/testComparesieqsc.ll
index 541aebb055347..094bbd458bedc 100644
--- a/llvm/test/CodeGen/PowerPC/testComparesieqsc.ll
+++ b/llvm/test/CodeGen/PowerPC/testComparesieqsc.ll
@@ -100,14 +100,14 @@ define dso_local signext i32 @test_ieqsc_sext_z(i8 signext %a) {
 ; CHECK-NEXT:    blr
 ; CHECK-BE-LABEL: test_ieqsc_sext_z:
 ; CHECK-BE:       # %bb.0: # %entry
-; CHECK-BE-NEXT:    clrldi r3, r3, 56
+; CHECK-BE-NEXT:    clrldi r3, r3, 32
 ; CHECK-BE-NEXT:    addic r3, r3, -1
 ; CHECK-BE-NEXT:    subfe r3, r3, r3
 ; CHECK-BE-NEXT:    blr
 ;
 ; CHECK-LE-LABEL: test_ieqsc_sext_z:
 ; CHECK-LE:       # %bb.0: # %entry
-; CHECK-LE-NEXT:    clrldi r3, r3, 56
+; CHECK-LE-NEXT:    clrldi r3, r3, 32
 ; CHECK-LE-NEXT:    addic r3, r3, -1
 ; CHECK-LE-NEXT:    subfe r3, r3, r3
 ; CHECK-LE-NEXT:    blr
diff --git a/llvm/test/CodeGen/PowerPC/testComparesieqss.ll b/llvm/test/CodeGen/PowerPC/testComparesieqss.ll
index 67e1729f2488e..eaf251077273e 100644
--- a/llvm/test/CodeGen/PowerPC/testComparesieqss.ll
+++ b/llvm/test/CodeGen/PowerPC/testComparesieqss.ll
@@ -100,14 +100,14 @@ define dso_local signext i32 @test_ieqss_sext_z(i16 signext %a) {
 ; CHECK-NEXT:    blr
 ; CHECK-BE-LABEL: test_ieqss_sext_z:
 ; CHECK-BE:       # %bb.0: # %entry
-; CHECK-BE-NEXT:    clrldi r3, r3, 48
+; CHECK-BE-NEXT:    clrldi r3, r3, 32
 ; CHECK-BE-NEXT:    addic r3, r3, -1
 ; CHECK-BE-NEXT:    subfe r3, r3, r3
 ; CHECK-BE-NEXT:    blr
 ;
 ; CHECK-LE-LABEL: test_ieqss_sext_z:
 ; CHECK-LE:       # %bb.0: # %entry
-; CHECK-LE-NEXT:    clrldi r3, r3, 48
+; CHECK-LE-NEXT:    clrldi r3, r3, 32
 ; CHECK-LE-NEXT:    addic r3, r3, -1
 ; CHECK-LE-NEXT:    subfe r3, r3, r3
 ; CHECK-LE-NEXT:    blr
diff --git a/llvm/test/CodeGen/PowerPC/testCompareslleqsc.ll b/llvm/test/CodeGen/PowerPC/testCompareslleqsc.ll
index 75f3017ac0c4f..c920a64764f00 100644
--- a/llvm/test/CodeGen/PowerPC/testCompareslleqsc.ll
+++ b/llvm/test/CodeGen/PowerPC/testCompareslleqsc.ll
@@ -100,14 +100,14 @@ define i64 @test_lleqsc_sext_z(i8 signext %a) {
 ; CHECK-NEXT:    blr
 ; CHECK-BE-LABEL: test_lleqsc_sext_z:
 ; CHECK-BE:       # %bb.0: # %entry
-; CHECK-BE-NEXT:    clrldi r3, r3, 56
+; CHECK-BE-NEXT:    clrldi r3, r3, 32
 ; CHECK-BE-NEXT:    addic r3, r3, -1
 ; CHECK-BE-NEXT:    subfe r3, r3, r3
 ; CHECK-BE-NEXT:    blr
 ;
 ; CHECK-LE-LABEL: test_lleqsc_sext_z:
 ; CHECK-LE:       # %bb.0: # %entry
-; CHECK-LE-NEXT:    clrldi r3, r3, 56
+; CHECK-LE-NEXT:    clrldi r3, r3, 32
 ; CHECK-LE-NEXT:    addic r3, r3, -1
 ; CHECK-LE-NEXT:    subfe r3, r3, r3
 ; CHECK-LE-NEXT:    blr
diff --git a/llvm/test/CodeGen/PowerPC/testCompareslleqss.ll b/llvm/test/CodeGen/PowerPC/testCompareslleqss.ll
index 0670168426a8a..84ef41ea2a817 100644
--- a/llvm/test/CodeGen/PowerPC/testCompareslleqss.ll
+++ b/llvm/test/CodeGen/PowerPC/testCompareslleqss.ll
@@ -99,14 +99,14 @@ define i64 @test_lleqss_sext_z(i16 signext %a) {
 ; CHECK-NEXT:    blr
 ; CHECK-BE-LABEL: test_lleqss_sext_z:
 ; CHECK-BE:       # %bb.0: # %entry
-; CHECK-BE-NEXT:    clrldi r3, r3, 48
+; CHECK-BE-NEXT:    clrldi r3, r3, 32
 ; CHECK-BE-NEXT:    addic r3, r3, -1
 ; CHECK-BE-NEXT:    subfe r3, r3, r3
 ; CHECK-BE-NEXT:    blr
 ;
 ; CHECK-LE-LABEL: test_lleqss_sext_z:
 ; CHECK-LE:       # %bb.0: # %entry
-; CHECK-LE-NEXT:    clrldi r3, r3, 48
+; CHECK-LE-NEXT:    clrldi r3, r3, 32
 ; CHECK-LE-NEXT:    addic r3, r3, -1
 ; CHECK-LE-NEXT:    subfe r3, r3, r3
 ; CHECK-LE-NEXT:    blr

@diggerlin diggerlin requested review from RolandF77 and amy-kwan May 26, 2026 17:58
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