[RISCV] Use vmv.s.x instead of vfmv.s.f when the floating point scalar is 0.

Use integer vector scalar move instruction when move 0 to avoid add a integer-float move instruction.

Differential Revision: https://reviews.llvm.org/D116365

Author: jacquesguan

llvm/lib/Target/RISCV/RISCVInstrInfoVVLPatterns.td

@@ -1367,6 +1367,11 @@ let Predicates = [HasVInstructionsAnyF] in {
 
 // 17.2. Floating-Point Scalar Move Instructions
 foreach vti = AllFloatVectors in {
+  def : Pat<(vti.Vector (riscv_vfmv_s_f_vl (vti.Vector vti.RegClass:$merge),
+                                           (vti.Scalar (fpimm0)),
+                                           VLOpFrag)),
+            (!cast<Instruction>("PseudoVMV_S_X_"#vti.LMul.MX)
+                vti.RegClass:$merge, X0, GPR:$vl, vti.Log2SEW)>;
   def : Pat<(vti.Vector (riscv_vfmv_s_f_vl (vti.Vector vti.RegClass:$merge),
                                            vti.ScalarRegClass:$rs1,
                                            VLOpFrag)),

llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fp-buildvec.ll

@@ -86,9 +86,8 @@ define void @buildvec_dominant0_v2f32(<2 x float>* %x) {
 ; CHECK-NEXT:    addi a1, a1, %lo(.LCPI2_0)
 ; CHECK-NEXT:    vsetivli zero, 2, e32, mf2, ta, mu
 ; CHECK-NEXT:    vlse32.v v8, (a1), zero
-; CHECK-NEXT:    fmv.w.x ft0, zero
 ; CHECK-NEXT:    vsetvli zero, zero, e32, mf2, tu, mu
-; CHECK-NEXT:    vfmv.s.f v8, ft0
+; CHECK-NEXT:    vmv.s.x v8, zero
 ; CHECK-NEXT:    vse32.v v8, (a0)
 ; CHECK-NEXT:    ret
   store <2 x float> <float 0.0, float 1.0>, <2 x float>* %x
@@ -118,8 +117,7 @@ define void @buildvec_dominant0_v4f32(<4 x float>* %x) {
 ; CHECK-NEXT:    lui a1, %hi(.LCPI4_0)
 ; CHECK-NEXT:    addi a1, a1, %lo(.LCPI4_0)
 ; CHECK-NEXT:    vlse32.v v8, (a1), zero
-; CHECK-NEXT:    fmv.w.x ft0, zero
-; CHECK-NEXT:    vfmv.s.f v9, ft0
+; CHECK-NEXT:    vmv.s.x v9, zero
 ; CHECK-NEXT:    vsetivli zero, 3, e32, m1, tu, mu
 ; CHECK-NEXT:    vslideup.vi v8, v9, 2
 ; CHECK-NEXT:    vsetivli zero, 4, e32, m1, ta, mu
@@ -132,9 +130,8 @@ define void @buildvec_dominant0_v4f32(<4 x float>* %x) {
 define void @buildvec_dominant1_v4f32(<4 x float>* %x, float %f) {
 ; CHECK-LABEL: buildvec_dominant1_v4f32:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    fmv.w.x ft0, zero
 ; CHECK-NEXT:    vsetivli zero, 4, e32, m1, ta, mu
-; CHECK-NEXT:    vfmv.s.f v8, ft0
+; CHECK-NEXT:    vmv.s.x v8, zero
 ; CHECK-NEXT:    vfmv.v.f v9, fa0
 ; CHECK-NEXT:    vsetivli zero, 2, e32, m1, tu, mu
 ; CHECK-NEXT:    vslideup.vi v9, v8, 1