[llvm] [AMDGPU] Prefer `s_memtime` for `readcyclecounter` on GFX10 (PR #80211)

[Matt Arsenault via llvm-commits]

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@@ -1065,8 +1065,6 @@ def : GCNPat <
   (REG_SEQUENCE SReg_64,
     (S_GETREG_B32 getHwRegImm<HWREG.SHADER_CYCLES, 0, -12>.ret), sub0,
     (S_MOV_B32 (i32 0)), sub1)> {
-  // Prefer this to s_memtime because it has lower and more predictable latency.
-  let AddedComplexity = 1;
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arsenm wrote:

Is the whole pattern just dead now? I would expect to need either an extra predicate for is-useful or modify the HasShaderCyclesRegister predicate 

https://github.com/llvm/llvm-project/pull/80211