[llvm] [AMDGPU][DAGCombiner][GlobalISel] Prevent FMA contraction when multiply cannot be eliminated (PR #169735)

[Matt Arsenault via llvm-commits]

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@@ -184,18 +165,15 @@ define amdgpu_kernel void @multiple_use_fadd_fmad_f32(ptr addrspace(1) %out, flo
 ; GFX11-NEXT:    s_load_b128 s[0:3], s[4:5], 0x0
 ; GFX11-NEXT:    v_mov_b32_e32 v0, 0
 ; GFX11-NEXT:    s_waitcnt lgkmcnt(0)
-; GFX11-NEXT:    v_add_f32_e64 v1, |s2|, |s2|
-; GFX11-NEXT:    v_fma_f32 v2, |s2|, 2.0, s3
-; GFX11-NEXT:    global_store_b32 v0, v1, s[0:1] dlc
-; GFX11-NEXT:    s_waitcnt_vscnt null, 0x0
-; GFX11-NEXT:    global_store_b32 v0, v2, s[0:1] offset:4 dlc
+; GFX11-NEXT:    v_fma_f32 v1, |s2|, 2.0, s3
+; GFX11-NEXT:    global_store_b32 v0, v1, s[0:1] offset:4 dlc
 ; GFX11-NEXT:    s_waitcnt_vscnt null, 0x0
 ; GFX11-NEXT:    s_endpgm
   %out.gep.1 = getelementptr float, ptr addrspace(1) %out, i32 1
   %x.abs = call float @llvm.fabs.f32(float %x)
   %mul2 = fmul fast float %x.abs, 2.0
   %mad = fadd fast float %mul2, %y
-  store volatile float %mul2, ptr addrspace(1) %out
+  ; store volatile float %mul2, ptr addrspace(1) %out
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arsenm wrote:

Accidental break of existing test

https://github.com/llvm/llvm-project/pull/169735