diff options
Diffstat (limited to 'gas/config/tc-i386.c')
| -rw-r--r-- | gas/config/tc-i386.c | 84 |
1 files changed, 83 insertions, 1 deletions
diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c index ab52692..c51402a 100644 --- a/gas/config/tc-i386.c +++ b/gas/config/tc-i386.c @@ -5327,6 +5327,84 @@ optimize_encoding (void) } } +/* Try to shorten {nf} encodings, by shortening operand size or switching to + functionally identical encodings. */ + +static void +optimize_nf_encoding (void) +{ + if (i.tm.base_opcode == 0x80 + && (i.tm.extension_opcode == 0 || i.tm.extension_opcode == 5) + && i.suffix != BYTE_MNEM_SUFFIX + && !i.types[1].bitfield.byte + && !i.types[2].bitfield.byte + && i.op[0].imms->X_op == O_constant + && i.op[0].imms->X_add_number == 0x80) + { + /* Optimize: -O: + {nf} addw $0x80, ... -> {nf} subw $-0x80, ... + {nf} addl $0x80, ... -> {nf} subl $-0x80, ... + {nf} addq $0x80, ... -> {nf} subq $-0x80, ... + + {nf} subw $0x80, ... -> {nf} addw $-0x80, ... + {nf} subl $0x80, ... -> {nf} addl $-0x80, ... + {nf} subq $0x80, ... -> {nf} addq $-0x80, ... + */ + i.tm.base_opcode |= 3; + i.tm.extension_opcode ^= 5; + i.tm.opcode_modifier.w = 0; + i.op[0].imms->X_add_number = -i.op[0].imms->X_add_number; + + i.tm.operand_types[0].bitfield.imm8 = 0; + i.tm.operand_types[0].bitfield.imm8s = 1; + i.tm.operand_types[0].bitfield.imm16 = 0; + i.tm.operand_types[0].bitfield.imm32 = 0; + i.tm.operand_types[0].bitfield.imm32s = 0; + + i.types[0] = i.tm.operand_types[0]; + } + else if ((i.tm.base_opcode | 3) == 0x83 + && (i.tm.extension_opcode == 0 || i.tm.extension_opcode == 5) + && i.op[0].imms->X_op == O_constant + && (i.op[0].imms->X_add_number == 1 + || i.op[0].imms->X_add_number == -1 + /* While for wider than byte operations immediates were suitably + adjusted earlier on, 0xff in the byte case needs covering + explicitly. */ + || (i.op[0].imms->X_add_number == 0xff + && (i.suffix == BYTE_MNEM_SUFFIX + || i.types[i.operands - 1].bitfield.byte)))) + { + /* Optimize: -O: + {nf} add $1, ... -> {nf} inc ... + {nf} add $-1, ... -> {nf} dec ... + {nf} add $0xf...f, ... -> {nf} dec ... + + {nf} sub $1, ... -> {nf} dec ... + {nf} sub $-1, ... -> {nf} inc ... + {nf} sub $0xf...f, ... -> {nf} inc ... + */ + i.tm.base_opcode = 0xfe; + i.tm.extension_opcode + = (i.op[0].imms->X_add_number == 1) != (i.tm.extension_opcode == 0); + i.tm.opcode_modifier.w = 1; + + i.types[0] = i.types[1]; + i.types[1] = i.types[2]; + i.tm.operand_types[0] = i.tm.operand_types[1]; + i.tm.operand_types[1] = i.tm.operand_types[2]; + i.op[0] = i.op[1]; + i.op[1] = i.op[2]; + i.flags[0] = i.flags[1]; + i.flags[1] = i.flags[2]; + i.reloc[0] = i.reloc[1]; + i.reloc[1] = NO_RELOC; + + i.imm_operands = 0; + --i.operands; + } +} + static void s_noopt (int dummy ATTRIBUTE_UNUSED) { @@ -7206,7 +7284,11 @@ md_assemble (char *line) } if (optimize && !i.no_optimize && i.tm.opcode_modifier.optimize) - optimize_encoding (); + { + if (i.has_nf) + optimize_nf_encoding (); + optimize_encoding (); + } /* Past optimization there's no need to distinguish encoding_evex, encoding_evex512, and encoding_egpr anymore. */ |