[llvm] [AMDGPU][SIPreEmitPeephole] mustRetainExeczBranch: estimate ThenBlock cost using MachineTraceInfo (PR #111117)

[Matt Arsenault via llvm-commits]

Juan Manuel Martinez =?utf-8?q?Caamaño?= <juamarti at amd.com>,
Juan Manuel Martinez =?utf-8?q?Caamaño?= <juamarti at amd.com>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/111117 at github.com>


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@@ -13,7 +13,6 @@ define amdgpu_cs void @if_then(ptr addrspace(8) inreg %input, ptr addrspace(8) i
 ; GCN-NEXT:    s_or_b32 exec_lo, exec_lo, s0
 ; GCN-NEXT:    v_cmp_lt_u32_e32 vcc_lo, 3, v0
 ; GCN-NEXT:    s_and_saveexec_b32 s0, vcc_lo
-; GCN-NEXT:    s_cbranch_execz .LBB0_4
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arsenm wrote:

I'm surprised this branch is now deleted. I thought the cutoff for profitability would be somewhere around 6 instructions, but this block has 9 + the branch 

https://github.com/llvm/llvm-project/pull/111117