[RISCV] Add another potential combine to {double,float}-bitmanip-dagc…

…ombines.ll

(fcopysign a, (fneg b)) will be expanded to bitwise operations by
DAGTypeLegalizer::SoftenFloatRes_FCOPYSIGN if the floating point type isn't
legal. Arguably it might be worth doing a combine even if it is legal.

llvm-svn: 352240

llvm/test/CodeGen/RISCV/double-bitmanip-dagcombines.ll

@@ -78,3 +78,51 @@ define double @fabs(double %a) nounwind {
   %1 = call double @llvm.fabs.f64(double %a)
   ret double %1
 }
+
+declare double @llvm.copysign.f64(double, double)
+
+; DAGTypeLegalizer::SoftenFloatRes_FCOPYSIGN will convert to bitwise
+; operations if floating point isn't supported. A combine could be written to
+; do the same even when f64 is legal.
+
+define double @fcopysign_fneg(double %a, double %b) nounwind {
+; RV32I-LABEL: fcopysign_fneg:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    not a2, a3
+; RV32I-NEXT:    lui a3, 524288
+; RV32I-NEXT:    and a2, a2, a3
+; RV32I-NEXT:    addi a3, a3, -1
+; RV32I-NEXT:    and a1, a1, a3
+; RV32I-NEXT:    or a1, a1, a2
+; RV32I-NEXT:    ret
+;
+; RV32IFD-LABEL: fcopysign_fneg:
+; RV32IFD:       # %bb.0:
+; RV32IFD-NEXT:    addi sp, sp, -16
+; RV32IFD-NEXT:    sw a2, 8(sp)
+; RV32IFD-NEXT:    sw a3, 12(sp)
+; RV32IFD-NEXT:    fld ft0, 8(sp)
+; RV32IFD-NEXT:    sw a0, 8(sp)
+; RV32IFD-NEXT:    sw a1, 12(sp)
+; RV32IFD-NEXT:    fld ft1, 8(sp)
+; RV32IFD-NEXT:    fsgnjn.d ft0, ft1, ft0
+; RV32IFD-NEXT:    fsd ft0, 8(sp)
+; RV32IFD-NEXT:    lw a0, 8(sp)
+; RV32IFD-NEXT:    lw a1, 12(sp)
+; RV32IFD-NEXT:    addi sp, sp, 16
+; RV32IFD-NEXT:    ret
+;
+; RV64I-LABEL: fcopysign_fneg:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    addi a2, zero, -1
+; RV64I-NEXT:    slli a2, a2, 63
+; RV64I-NEXT:    not a1, a1
+; RV64I-NEXT:    and a1, a1, a2
+; RV64I-NEXT:    addi a2, a2, -1
+; RV64I-NEXT:    and a0, a0, a2
+; RV64I-NEXT:    or a0, a0, a1
+; RV64I-NEXT:    ret
+  %1 = fneg double %b
+  %2 = call double @llvm.copysign.f64(double %a, double %1)
+  ret double %2
+}

llvm/test/CodeGen/RISCV/float-bitmanip-dagcombines.ll

@@ -2,7 +2,7 @@
 ; RUN: llc -mtriple=riscv32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV32I %s
 ; RUN: llc -mtriple=riscv32 -mattr=+f -verify-machineinstrs < %s \
-; RUN:   | FileCheck -check-prefix=RV32I %s
+; RUN:   | FileCheck -check-prefix=RV32IF %s
 ; RUN: llc -mtriple=riscv64 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV64I %s
 
@@ -19,6 +19,12 @@ define float @fneg(float %a) nounwind {
 ; RV32I-NEXT:    xor a0, a0, a1
 ; RV32I-NEXT:    ret
 ;
+; RV32IF-LABEL: fneg:
+; RV32IF:       # %bb.0:
+; RV32IF-NEXT:    lui a1, 524288
+; RV32IF-NEXT:    xor a0, a0, a1
+; RV32IF-NEXT:    ret
+;
 ; RV64I-LABEL: fneg:
 ; RV64I:       # %bb.0:
 ; RV64I-NEXT:    lui a1, 524288
@@ -38,6 +44,13 @@ define float @fabs(float %a) nounwind {
 ; RV32I-NEXT:    and a0, a0, a1
 ; RV32I-NEXT:    ret
 ;
+; RV32IF-LABEL: fabs:
+; RV32IF:       # %bb.0:
+; RV32IF-NEXT:    lui a1, 524288
+; RV32IF-NEXT:    addi a1, a1, -1
+; RV32IF-NEXT:    and a0, a0, a1
+; RV32IF-NEXT:    ret
+;
 ; RV64I-LABEL: fabs:
 ; RV64I:       # %bb.0:
 ; RV64I-NEXT:    lui a1, 524288
@@ -47,3 +60,44 @@ define float @fabs(float %a) nounwind {
   %1 = call float @llvm.fabs.f32(float %a)
   ret float %1
 }
+
+declare float @llvm.copysign.f32(float, float)
+
+; DAGTypeLegalizer::SoftenFloatRes_FCOPYSIGN will convert to bitwise
+; operations if floating point isn't supported. A combine could be written to
+; do the same even when f32 is legal.
+
+define float @fcopysign_fneg(float %a, float %b) nounwind {
+; RV32I-LABEL: fcopysign_fneg:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    not a1, a1
+; RV32I-NEXT:    lui a2, 524288
+; RV32I-NEXT:    and a1, a1, a2
+; RV32I-NEXT:    addi a2, a2, -1
+; RV32I-NEXT:    and a0, a0, a2
+; RV32I-NEXT:    or a0, a0, a1
+; RV32I-NEXT:    ret
+;
+; RV32IF-LABEL: fcopysign_fneg:
+; RV32IF:       # %bb.0:
+; RV32IF-NEXT:    lui a2, 524288
+; RV32IF-NEXT:    xor a1, a1, a2
+; RV32IF-NEXT:    fmv.w.x ft0, a1
+; RV32IF-NEXT:    fmv.w.x ft1, a0
+; RV32IF-NEXT:    fsgnj.s ft0, ft1, ft0
+; RV32IF-NEXT:    fmv.x.w a0, ft0
+; RV32IF-NEXT:    ret
+;
+; RV64I-LABEL: fcopysign_fneg:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    not a1, a1
+; RV64I-NEXT:    lui a2, 524288
+; RV64I-NEXT:    and a1, a1, a2
+; RV64I-NEXT:    addiw a2, a2, -1
+; RV64I-NEXT:    and a0, a0, a2
+; RV64I-NEXT:    or a0, a0, a1
+; RV64I-NEXT:    ret
+  %1 = fneg float %b
+  %2 = call float @llvm.copysign.f32(float %a, float %1)
+  ret float %2
+}