[RISCV] Fold (sext_inreg (xor (setcc), -1), i1) -> (add (setcc), -1). (#153855)

This improves all 3 vendor extensions that make sext_inreg i1 legal

Fixes #153781.

Author: topperc

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

@@ -16660,6 +16660,13 @@ performSIGN_EXTEND_INREGCombine(SDNode *N, SelectionDAG &DAG,
     return DAG.getNode(RISCVISD::SLLW, SDLoc(N), VT, Src.getOperand(0),
                        Src.getOperand(1));
 
+  // Fold (sext_inreg (xor (setcc), -1), i1) -> (add (setcc), -1)
+  if (Opc == ISD::XOR && SrcVT == MVT::i1 &&
+      isAllOnesConstant(Src.getOperand(1)) &&
+      Src.getOperand(0).getOpcode() == ISD::SETCC)
+    return DAG.getNode(ISD::ADD, SDLoc(N), VT, Src.getOperand(0),
+                       DAG.getAllOnesConstant(SDLoc(N), VT));
+
   return SDValue();
 }
 

llvm/test/CodeGen/RISCV/rv32xandesperf.ll

@@ -364,6 +364,19 @@ define i32 @sexti1_i32_2(i1 %a) {
   ret i32 %1
 }
 
+; Make sure we don't use not+nds.bfos
+define zeroext i8 @sexti1_i32_setcc(i32 signext %a) {
+; CHECK-LABEL: sexti1_i32_setcc:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    srli a0, a0, 31
+; CHECK-NEXT:    addi a0, a0, -1
+; CHECK-NEXT:    zext.b a0, a0
+; CHECK-NEXT:    ret
+  %icmp = icmp sgt i32 %a, -1
+  %sext = sext i1 %icmp to i8
+  ret i8 %sext
+}
+
 define i32 @sexti8_i32(i32 %a) {
 ; CHECK-LABEL: sexti8_i32:
 ; CHECK:       # %bb.0:

llvm/test/CodeGen/RISCV/rv32xtheadbb.ll

@@ -314,6 +314,26 @@ define i32 @sexti1_i32_2(i1 %a) nounwind {
   ret i32 %sext
 }
 
+; Make sure we don't use not+th.ext
+define zeroext i8 @sexti1_i32_setcc(i32 signext %a) {
+; RV32I-LABEL: sexti1_i32_setcc:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    srli a0, a0, 31
+; RV32I-NEXT:    addi a0, a0, -1
+; RV32I-NEXT:    zext.b a0, a0
+; RV32I-NEXT:    ret
+;
+; RV32XTHEADBB-LABEL: sexti1_i32_setcc:
+; RV32XTHEADBB:       # %bb.0:
+; RV32XTHEADBB-NEXT:    srli a0, a0, 31
+; RV32XTHEADBB-NEXT:    addi a0, a0, -1
+; RV32XTHEADBB-NEXT:    zext.b a0, a0
+; RV32XTHEADBB-NEXT:    ret
+  %icmp = icmp sgt i32 %a, -1
+  %sext = sext i1 %icmp to i8
+  ret i8 %sext
+}
+
 define i32 @sextb_i32(i32 %a) nounwind {
 ; RV32I-LABEL: sextb_i32:
 ; RV32I:       # %bb.0:

llvm/test/CodeGen/RISCV/rv64xandesperf.ll

@@ -277,6 +277,19 @@ define signext i32 @sexti1_i32_2(i1 %a) {
   ret i32 %1
 }
 
+; Make sure we don't use not+nds.bfos
+define zeroext i8 @sexti1_i32_setcc(i32 signext %a) {
+; CHECK-LABEL: sexti1_i32_setcc:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    srli a0, a0, 63
+; CHECK-NEXT:    addi a0, a0, -1
+; CHECK-NEXT:    zext.b a0, a0
+; CHECK-NEXT:    ret
+  %icmp = icmp sgt i32 %a, -1
+  %sext = sext i1 %icmp to i8
+  ret i8 %sext
+}
+
 define signext i32 @sexti8_i32(i32 signext %a) {
 ; CHECK-LABEL: sexti8_i32:
 ; CHECK:       # %bb.0:
@@ -334,6 +347,19 @@ define i64 @sexti1_i64_2(i1 %a) {
   ret i64 %1
 }
 
+; Make sure we don't use not+nds.bfos
+define zeroext i8 @sexti1_i64_setcc(i64 %a) {
+; CHECK-LABEL: sexti1_i64_setcc:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    srli a0, a0, 63
+; CHECK-NEXT:    addi a0, a0, -1
+; CHECK-NEXT:    zext.b a0, a0
+; CHECK-NEXT:    ret
+  %icmp = icmp sgt i64 %a, -1
+  %sext = sext i1 %icmp to i8
+  ret i8 %sext
+}
+
 define i64 @sexti8_i64(i64 %a) {
 ; CHECK-LABEL: sexti8_i64:
 ; CHECK:       # %bb.0:

llvm/test/CodeGen/RISCV/rv64xtheadbb.ll

@@ -635,6 +635,26 @@ define signext i32 @sexti1_i32_2(i1 %a) nounwind {
   ret i32 %sext
 }
 
+; Make sure we don't use not+th.ext
+define zeroext i8 @sexti1_i32_setcc(i32 signext %a) {
+; RV64I-LABEL: sexti1_i32_setcc:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    srli a0, a0, 63
+; RV64I-NEXT:    addi a0, a0, -1
+; RV64I-NEXT:    zext.b a0, a0
+; RV64I-NEXT:    ret
+;
+; RV64XTHEADBB-LABEL: sexti1_i32_setcc:
+; RV64XTHEADBB:       # %bb.0:
+; RV64XTHEADBB-NEXT:    srli a0, a0, 63
+; RV64XTHEADBB-NEXT:    addi a0, a0, -1
+; RV64XTHEADBB-NEXT:    zext.b a0, a0
+; RV64XTHEADBB-NEXT:    ret
+  %icmp = icmp sgt i32 %a, -1
+  %sext = sext i1 %icmp to i8
+  ret i8 %sext
+}
+
 define i64 @sexti1_i64(i64 %a) nounwind {
 ; RV64I-LABEL: sexti1_i64:
 ; RV64I:       # %bb.0:
@@ -666,6 +686,26 @@ define i64 @sexti1_i64_2(i1 %a) nounwind {
   ret i64 %sext
 }
 
+; Make sure we don't use not+th.ext
+define zeroext i8 @sexti1_i64_setcc(i64 %a) {
+; RV64I-LABEL: sexti1_i64_setcc:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    srli a0, a0, 63
+; RV64I-NEXT:    addi a0, a0, -1
+; RV64I-NEXT:    zext.b a0, a0
+; RV64I-NEXT:    ret
+;
+; RV64XTHEADBB-LABEL: sexti1_i64_setcc:
+; RV64XTHEADBB:       # %bb.0:
+; RV64XTHEADBB-NEXT:    srli a0, a0, 63
+; RV64XTHEADBB-NEXT:    addi a0, a0, -1
+; RV64XTHEADBB-NEXT:    zext.b a0, a0
+; RV64XTHEADBB-NEXT:    ret
+  %icmp = icmp sgt i64 %a, -1
+  %sext = sext i1 %icmp to i8
+  ret i8 %sext
+}
+
 define signext i32 @sextb_i32(i32 signext %a) nounwind {
 ; RV64I-LABEL: sextb_i32:
 ; RV64I:       # %bb.0:

llvm/test/CodeGen/RISCV/xqcibm-extract.ll

@@ -47,6 +47,33 @@ define i32 @sexti1_i32_2(i32 %a) {
   ret i32 %shr
 }
 
+; Make sure we don't use not+qc.ext
+define zeroext i8 @sexti1_i32_setcc(i32 signext %a) {
+; RV32I-LABEL: sexti1_i32_setcc:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    srli a0, a0, 31
+; RV32I-NEXT:    addi a0, a0, -1
+; RV32I-NEXT:    zext.b a0, a0
+; RV32I-NEXT:    ret
+;
+; RV32XQCIBM-LABEL: sexti1_i32_setcc:
+; RV32XQCIBM:       # %bb.0:
+; RV32XQCIBM-NEXT:    srli a0, a0, 31
+; RV32XQCIBM-NEXT:    addi a0, a0, -1
+; RV32XQCIBM-NEXT:    qc.extu a0, a0, 8, 0
+; RV32XQCIBM-NEXT:    ret
+;
+; RV32XQCIBMZBB-LABEL: sexti1_i32_setcc:
+; RV32XQCIBMZBB:       # %bb.0:
+; RV32XQCIBMZBB-NEXT:    srli a0, a0, 31
+; RV32XQCIBMZBB-NEXT:    addi a0, a0, -1
+; RV32XQCIBMZBB-NEXT:    qc.extu a0, a0, 8, 0
+; RV32XQCIBMZBB-NEXT:    ret
+  %icmp = icmp sgt i32 %a, -1
+  %sext = sext i1 %icmp to i8
+  ret i8 %sext
+}
+
 
 define i32 @sexti8_i32(i8 %a) nounwind {
 ; RV32I-LABEL: sexti8_i32: