[llvm] [AMDGPU] Allow folding FMA with SGPR and immediate operand on GFX10+ (PR #72258)

[Jay Foad via llvm-commits]

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@@ -715,12 +715,33 @@ define amdgpu_ps i32 @s_mul_fma_32_f32(float inreg %x, float inreg %y) {
 ; GFX9-NEXT:    v_readfirstlane_b32 s0, v0
 ; GFX9-NEXT:    ; return to shader part epilog
 ;
-; GFX1011-LABEL: s_mul_fma_32_f32:
-; GFX1011:       ; %bb.0:
-; GFX1011-NEXT:    v_mov_b32_e32 v0, s1
-; GFX1011-NEXT:    v_fmac_f32_e64 v0, 0x42000000, s0
-; GFX1011-NEXT:    v_readfirstlane_b32 s0, v0
-; GFX1011-NEXT:    ; return to shader part epilog
+; GFX10-SDAG-LABEL: s_mul_fma_32_f32:
+; GFX10-SDAG:       ; %bb.0:
+; GFX10-SDAG-NEXT:    v_mov_b32_e32 v0, s1
+; GFX10-SDAG-NEXT:    v_fmamk_f32 v0, s0, 0x42000000, v0
+; GFX10-SDAG-NEXT:    v_readfirstlane_b32 s0, v0
+; GFX10-SDAG-NEXT:    ; return to shader part epilog
+;
+; GFX10-GISEL-LABEL: s_mul_fma_32_f32:
+; GFX10-GISEL:       ; %bb.0:
+; GFX10-GISEL-NEXT:    v_mov_b32_e32 v0, s1
+; GFX10-GISEL-NEXT:    v_fmac_f32_e64 v0, 0x42000000, s0
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jayfoad wrote:

We are only successfully folding to fmamk for sdag. To make it work for gisel we need something like #72128.

https://github.com/llvm/llvm-project/pull/72258