[PATCH] D144166: [RISCV] For rv32, accept constants like 0xfffff800 as a valid simm12.

[Craig Topper via Phabricator via llvm-commits]

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Internally we store constants in int64_t after parsing, but this is
kind of an implementation detail. If we only supported rv32, we might
have chosen int32_t.

For rv32, I think it makes sense to accept the constants that we
would accept if int32_t was the internal type. In fact we already
do this for the `li` alias. This patch extends this to sign
extended constants for other instructions.

This matches the GNU assembler. The difference between LLVM and gcc
was previously noted here. https://github.com/riscv-non-isa/riscv-asm-manual/pull/71


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D144166

Files:
  llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
  llvm/test/MC/RISCV/rv32c-only-valid.s
  llvm/test/MC/RISCV/rv32i-only-valid.s
  llvm/test/MC/RISCV/rvv/rv32-immediate.s

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