[mips] Fix sc, scs, ll, lld instructions expanding

Authored by atanasyan on Nov 21 2019, 2:33 PM.


[mips] Fix sc, scs, ll, lld instructions expanding

There are a couple of bugs with the sc, scs, ll, lld instructions expanding:

  1. On R6 these instruction pack immediate offset into a 9-bit field. Now

if an immediate exceeds 9-bits assembler does not perform expansion and
just rejects such instruction.

  1. On 64-bit non-PIC code if an operand is a symbol assembler generates

incorrect sequence of instructions. It uses R_MIPS_HI16 and R_MIPS_LO16
relocations and skips R_MIPS_HIGHEST and R_MIPS_HIGHER ones.

To solve these problems this patch:

  • Introduces mem_simm9_exp to mark 9-bit memory immediate operands

which require expansion. Probably later all mem_simm9 operands will be
able to migrate on mem_simm9_exp and we rename it to mem_simm9.

  • Adds new OPERAND_MEM_SIMM9 operand type and assigns it to the

mem_simm9_exp. That allows to know operand size in the processInstruction
method and decide whether we need to expand instruction.

  • Adds expandMem9Inst method to expand instructions with 9-bit memory

immediate operand. This method just load immediate into a "base"
register used by origibal instruction:

sc $2, 256($sp) => addiu  $1, $sp, 256
                   sc     $2, 0($1)
  • Fix expandMem16Inst to support a correct set of relocations for

symbol loading in case of 64-bit non-PIC code.

ll $12, symbol => lui    $12, 0
                      R_MIPS_HIGHEST symbol
                  daddiu $12, $12, 0
                      R_MIPS_HIGHER symbol
                  dsll   $12, $12, 16
                  daddiu $12, $12, 0
                      R_MIPS_HI16 symbol
                  dsll   $12, $12, 16
                  ll     $12, 0($12)
                      R_MIPS_LO16 symbol
  • Fix expandMem16Inst to unify handling of 3 and 4 operands


  • Delete unused now MipsTargetStreamer::emitSCWithSymOffset method.

Task for next patches - implement expanding for other instructions use
mem_simm9 operand and other mem_simm## operands.

Differential Revision: https://reviews.llvm.org/D70648