Unverified Commit 228ef85b authored by Nikita Popov's avatar Nikita Popov Committed by GitHub
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[X86] Return more accurate getNumSupportedRegs() (NFC) (#71690) 

https://github.com/llvm/llvm-project/pull/70222 introduced a hook to
return a more accurate number of registers supported for a specific
subtarget (rather than target). However, while x86 registers were
reordered to allow using this, the implementation currently still always
returns NUM_TARGET_REGS.

Adjust it to return a smaller number of registers depending on
availability of avx/avx512/amx.

The actual impact of this seems to be pretty small, on the order of
0.05%.
parent 14b5abbf

llvm/lib/Target/X86/X86RegisterInfo.cpp

+9 −1
Original line number Diff line number Diff line
@@ -634,7 +634,15 @@ unsigned X86RegisterInfo::getNumSupportedRegs(const MachineFunction &MF) const { 
         (X86::K6_K7 + 1 == X86::TMMCFG) &&

         (X86::TMM7 + 1 == X86::NUM_TARGET_REGS) &&

         "Register number may be incorrect");

  return X86::NUM_TARGET_REGS;



  const X86Subtarget &ST = MF.getSubtarget<X86Subtarget>();

  if (ST.hasAMXTILE())

    return X86::TMM7 + 1;

  if (ST.hasAVX512())

    return X86::K6_K7 + 1;

  if (ST.hasAVX())

    return X86::YMM15 + 1;

  return X86::R15WH + 1;

}



bool X86RegisterInfo::isArgumentRegister(const MachineFunction &MF,