[PATCH] D66553: [mips] Reduce number of instructions used for loading a global symbol's value

[Simon Atanasyan via Phabricator via llvm-commits]

atanasyan created this revision.
Herald added subscribers: jrtc27, hiraditya, arichardson, sdardis.
Herald added a project: LLVM.
atanasyan added a parent revision: D66228: [mips] Fix 64-bit address loading in case of applying 32-bit mask to the result.

Now `lw/sw $reg, sym+offset` pseudo instructions for global symbol `sym` are lowering into the following three instructions.

  lw     $reg, %got(symbol)($gp)
  addiu  $reg, $reg, offset
  lw/sw  $reg, 0($reg)

It's possible to reduce the number of instructions by taking the offset in account in the final `lw/sw` command. This patch implements that optimization.

  lw     $reg, %got(symbol)($gp)
  lw/sw  $reg, offset($reg)


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D66553

Files:
  llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
  llvm/test/MC/Mips/mips-expansions.s
  llvm/test/MC/Mips/mips64-expansions.s

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