[TargetLowering][RISCV] Don't transform (seteq/ne (sext_inreg X, VT), C1) -> (seteq/ne (zext_inreg X, VT), C1) if the sext_inreg is cheaper

RISCV has to use 2 shifts for (i64 (zext_inreg X, i32)), but we
can use addiw rd, rs1, x0 for sext_inreg. We already understood this
when type legalizing i32 seteq/ne on rv64. But this transform in
SimplifySetCC would sometimes undo it.

Reviewed By: luismarques

Differential Revision: https://reviews.llvm.org/D95289

llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp

@@ -3736,7 +3736,9 @@ SDValue TargetLowering::SimplifySetCC(EVT VT, SDValue N0, SDValue N1,
         break; // todo, be more careful with signed comparisons
       }
     } else if (N0.getOpcode() == ISD::SIGN_EXTEND_INREG &&
-               (Cond == ISD::SETEQ || Cond == ISD::SETNE)) {
+               (Cond == ISD::SETEQ || Cond == ISD::SETNE) &&
+               !isSExtCheaperThanZExt(cast<VTSDNode>(N0.getOperand(1))->getVT(),
+                                      OpVT)) {
       EVT ExtSrcTy = cast<VTSDNode>(N0.getOperand(1))->getVT();
       unsigned ExtSrcTyBits = ExtSrcTy.getSizeInBits();
       EVT ExtDstTy = N0.getValueType();

llvm/test/CodeGen/RISCV/double-stack-spill-restore.ll

@@ -19,7 +19,7 @@ define double @func(double %d, i32 %n) nounwind {
 ; RV32IFD-NEXT:    lw a0, 16(sp)
 ; RV32IFD-NEXT:    lw a1, 20(sp)
 ; RV32IFD-NEXT:    fsd ft0, 8(sp) # 8-byte Folded Spill
-; RV32IFD-NEXT:    call func
+; RV32IFD-NEXT:    call func@plt
 ; RV32IFD-NEXT:    sw a0, 16(sp)
 ; RV32IFD-NEXT:    sw a1, 20(sp)
 ; RV32IFD-NEXT:    fld ft0, 16(sp)
@@ -37,15 +37,14 @@ define double @func(double %d, i32 %n) nounwind {
 ; RV64IFD:       # %bb.0: # %entry
 ; RV64IFD-NEXT:    addi sp, sp, -16
 ; RV64IFD-NEXT:    sd ra, 8(sp) # 8-byte Folded Spill
-; RV64IFD-NEXT:    slli a2, a1, 32
+; RV64IFD-NEXT:    sext.w a2, a1
-; RV64IFD-NEXT:    srli a2, a2, 32
 ; RV64IFD-NEXT:    fmv.d.x ft0, a0
 ; RV64IFD-NEXT:    beqz a2, .LBB0_2
 ; RV64IFD-NEXT:  # %bb.1: # %if.else
 ; RV64IFD-NEXT:    addi a1, a1, -1
 ; RV64IFD-NEXT:    fmv.x.d a0, ft0
 ; RV64IFD-NEXT:    fsd ft0, 0(sp) # 8-byte Folded Spill
-; RV64IFD-NEXT:    call func
+; RV64IFD-NEXT:    call func@plt
 ; RV64IFD-NEXT:    fmv.d.x ft0, a0
 ; RV64IFD-NEXT:    fld ft1, 0(sp) # 8-byte Folded Reload
 ; RV64IFD-NEXT:    fadd.d ft0, ft0, ft1

llvm/test/CodeGen/RISCV/setcc-logic.ll

@@ -18,8 +18,7 @@ define i1 @and_icmp_eq(i32 %a, i32 %b, i32 %c, i32 %d) nounwind {
 ; RV64I-NEXT:    xor a0, a0, a1
 ; RV64I-NEXT:    xor a1, a2, a3
 ; RV64I-NEXT:    or a0, a0, a1
-; RV64I-NEXT:    slli a0, a0, 32
+; RV64I-NEXT:    sext.w a0, a0
-; RV64I-NEXT:    srli a0, a0, 32
 ; RV64I-NEXT:    seqz a0, a0
 ; RV64I-NEXT:    ret
   %cmp1 = icmp eq i32 %a, %b
@@ -42,8 +41,7 @@ define i1 @or_icmp_ne(i32 %a, i32 %b, i32 %c, i32 %d) nounwind {
 ; RV64I-NEXT:    xor a0, a0, a1
 ; RV64I-NEXT:    xor a1, a2, a3
 ; RV64I-NEXT:    or a0, a0, a1
-; RV64I-NEXT:    slli a0, a0, 32
+; RV64I-NEXT:    sext.w a0, a0
-; RV64I-NEXT:    srli a0, a0, 32
 ; RV64I-NEXT:    snez a0, a0
 ; RV64I-NEXT:    ret
   %cmp1 = icmp ne i32 %a, %b
@@ -87,10 +85,8 @@ define i1 @and_icmps_const_1bit_diff(i32 %x) nounwind {
 ; RV64I-LABEL: and_icmps_const_1bit_diff:
 ; RV64I:       # %bb.0:
 ; RV64I-NEXT:    addi a0, a0, -44
-; RV64I-NEXT:    addi a1, zero, 1
+; RV64I-NEXT:    andi a0, a0, -17
-; RV64I-NEXT:    slli a1, a1, 32
+; RV64I-NEXT:    sext.w a0, a0
-; RV64I-NEXT:    addi a1, a1, -17
-; RV64I-NEXT:    and a0, a0, a1
 ; RV64I-NEXT:    snez a0, a0
 ; RV64I-NEXT:    ret
   %a = icmp ne i32 %x, 44
@@ -111,8 +107,7 @@ define i1 @and_icmps_const_not1bit_diff(i32 %x) nounwind {
 ;
 ; RV64I-LABEL: and_icmps_const_not1bit_diff:
 ; RV64I:       # %bb.0:
-; RV64I-NEXT:    slli a0, a0, 32
+; RV64I-NEXT:    sext.w a0, a0
-; RV64I-NEXT:    srli a0, a0, 32
 ; RV64I-NEXT:    addi a1, a0, -44
 ; RV64I-NEXT:    snez a1, a1
 ; RV64I-NEXT:    addi a0, a0, -92

llvm/test/CodeGen/RISCV/sext-zext-trunc.ll

@@ -485,8 +485,7 @@ define i32 @sext_of_not_cmp_i32(i32 %x) {
 ;
 ; RV64I-LABEL: sext_of_not_cmp_i32:
 ; RV64I:       # %bb.0:
-; RV64I-NEXT:    slli a0, a0, 32
+; RV64I-NEXT:    sext.w a0, a0
-; RV64I-NEXT:    srli a0, a0, 32
 ; RV64I-NEXT:    addi a0, a0, -7
 ; RV64I-NEXT:    snez a0, a0
 ; RV64I-NEXT:    neg a0, a0
@@ -530,8 +529,7 @@ define i32 @dec_of_zexted_cmp_i32(i32 %x) {
 ;
 ; RV64I-LABEL: dec_of_zexted_cmp_i32:
 ; RV64I:       # %bb.0:
-; RV64I-NEXT:    slli a0, a0, 32
+; RV64I-NEXT:    sext.w a0, a0
-; RV64I-NEXT:    srli a0, a0, 32
 ; RV64I-NEXT:    addi a0, a0, -7
 ; RV64I-NEXT:    seqz a0, a0
 ; RV64I-NEXT:    addi a0, a0, -1