[PATCH] D52298: [RISCV][MC] Add support for evaluating constant symbols as immediates

[Alex Bradbury via Phabricator via llvm-commits]

asb created this revision.
asb added reviewers: shiva0217, apazos.
Herald added subscribers: jocewei, PkmX, rkruppe, the_o, brucehoult, MartinMosbeck, rogfer01, mgrang, edward-jones, zzheng, jrtc27, kito-cheng, niosHD, sabuasal, simoncook, johnrusso, rbar.

This further improves compatibility with GNU as, allowing input such as the following to be assembled:

  .equ CONST, 0x123456
  li a0, CONST
  addi a0, a0, %lo(CONST)
  
  .equ CONST, 1
  slli a0, a0, CONST

Note that we don't have perfect compatibility with gas, as it will accept the following which we reject:

  addi a0, a0, %lo(CONST)
  .equ CONST, 0x123456

I believe that passing SetUsed=false to Sym.getVariableValue is correct - or at least that allows .equ to be used multiple times with the same symbol name in a way that matches gas. I'd appreciate a second opinion though.


Repository:
  rL LLVM

https://reviews.llvm.org/D52298

Files:
  lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
  test/MC/RISCV/rv32i-aliases-valid.s
  test/MC/RISCV/rv32i-valid.s
  test/MC/RISCV/rv64i-aliases-valid.s
  test/MC/RISCV/rv64i-valid.s

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