[llvm] [X86] Allow EVEX compression for mask registers (PR #171980)

[Simon Pilgrim via llvm-commits]

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@@ -187,6 +189,53 @@ static bool CompressEVEXImpl(MachineInstr &MI, MachineBasicBlock &MBB,
   if (TSFlags & (X86II::EVEX_K | X86II::EVEX_L2))
     return false;
 
+  // Try to compress VPMOV*2M + KMOV chain patterns:
+  //   vpmovd2m %xmm0, %k0     ->   vmovmskps %xmm0, %eax
+  //   kmovb %k0, %eax              (erase this)
+  unsigned Opc = MI.getOpcode();
+  if ((Opc == X86::VPMOVD2MZ128kr || Opc == X86::VPMOVD2MZ256kr) &&
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RKSimon wrote:

Handle VMOVMSKPD as well?

https://github.com/llvm/llvm-project/pull/171980