[SelectionDAG] [NFC] Add pre-commit test for PR66701.

Author: srpande

llvm/test/CodeGen/AMDGPU/fma.ll

@@ -154,3 +154,27 @@ define float @fold_fmul_distributive(float %x, float %y) {
   %fmul = fmul contract float %fadd, %x
   ret float %fmul
 }
+
+; test to make sure contract is not dropped such that we can generate fma from following mul/add
+define amdgpu_kernel void @vec_mul_scalar_add_fma(<2 x float> %a, <2 x float> %b, float %c1, ptr addrspace(1) %inptr) {
+; GFX906-LABEL: vec_mul_scalar_add_fma:
+; GFX906:       ; %bb.0:
+; GFX906-NEXT:    s_load_dwordx4 s[4:7], s[0:1], 0x24
+; GFX906-NEXT:    s_waitcnt lgkmcnt(0)
+; GFX906-NEXT:    s_load_dword s5, s[0:1], 0x34
+; GFX906-NEXT:    s_load_dwordx2 s[2:3], s[0:1], 0x3c
+; GFX906-NEXT:    v_mov_b32_e32 v0, 0
+; GFX906-NEXT:    v_mov_b32_e32 v1, s6
+; GFX906-NEXT:    v_mul_f32_e32 v1, s4, v1
+; GFX906-NEXT:    s_waitcnt lgkmcnt(0)
+; GFX906-NEXT:    v_add_f32_e32 v1, s5, v1
+; GFX906-NEXT:    global_store_dword v0, v1, s[2:3] offset:4
+; GFX906-NEXT:    s_endpgm
+  %gep = getelementptr float, ptr addrspace(1) %inptr, i32 1
+  %c = shufflevector <2 x float> %a, <2 x float> poison, <2 x i32> zeroinitializer
+  %mul = fmul contract <2 x float> %c, %b
+  %elv = extractelement <2 x float> %mul, i64 0
+  %add = fadd contract float %elv, %c1
+  store float %add, ptr addrspace(1) %gep, align 4
+  ret void
+}