[llvm] [AMDGPU] Fix soft clause hazards missed past the lookahead window (PR #220806)

[Arseniy Obolenskiy via llvm-commits]

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@@ -56225,6 +56226,7 @@ define inreg <32 x float> @bitcast_v128i8_to_v32f32_scalar(<128 x i8> inreg %a,
 ; GFX9-NEXT:    buffer_load_ushort v25, off, s[0:3], s32 offset:140
 ; GFX9-NEXT:    buffer_load_ushort v24, off, s[0:3], s32 offset:136
 ; GFX9-NEXT:    buffer_load_ushort v23, off, s[0:3], s32 offset:132
+; GFX9-NEXT:    s_nop 0
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aobolensk wrote:

Here is it is real, store reads v0, five loads follow, then a load writes v0 again

That WAR is 6 instrs back, past the old window

https://github.com/llvm/llvm-project/pull/220806