1.14. CONDITIONAL JUMPS
.text:000000C8
; all 3 conditions were false, so just finish:
.text:000000C8 loc_C8: # CODE XREF: f_signed+A0
.text:000000C8 move $sp, $fp
.text:000000CC lw $ra, 0x20+var_4($sp)
.text:000000D0 lw $fp, 0x20+var_8($sp)
.text:000000D4 addiu $sp, 0x20
.text:000000D8 jr $ra
.text:000000DC or $at, $zero ; branch delay slot, NOP
.text:000000DC # End of function f_signed
SLT REG0, REG0, REG1is reduced by IDA to its shorter form:
SLT REG0, REG1.
We also see thereBEQZpseudo instruction (“Branch if Equal to Zero”),
which are in factBEQ REG, $ZERO, LABEL.
The unsigned version is just the same, butSLTU(unsigned version, hence “U” in name) is used instead of
SLT:
Listing 1.117: Non-optimizing GCC 4.4.5 (IDA).text:000000E0 f_unsigned: # CODE XREF: main+28
.text:000000E0
.text:000000E0 var_10 = -0x10
.text:000000E0 var_8 = -8
.text:000000E0 var_4 = -4
.text:000000E0 arg_0 = 0
.text:000000E0 arg_4 = 4
.text:000000E0
.text:000000E0 addiu $sp, -0x20
.text:000000E4 sw $ra, 0x20+var_4($sp)
.text:000000E8 sw $fp, 0x20+var_8($sp)
.text:000000EC move $fp, $sp
.text:000000F0 la $gp, __gnu_local_gp
.text:000000F8 sw $gp, 0x20+var_10($sp)
.text:000000FC sw $a0, 0x20+arg_0($fp)
.text:00000100 sw $a1, 0x20+arg_4($fp)
.text:00000104 lw $v1, 0x20+arg_0($fp)
.text:00000108 lw $v0, 0x20+arg_4($fp)
.text:0000010C or $at, $zero
.text:00000110 sltu $v0, $v1
.text:00000114 beqz $v0, loc_13C
.text:00000118 or $at, $zero
.text:0000011C lui $v0, (unk_230 >> 16)
.text:00000120 addiu $a0, $v0, (unk_230 & 0xFFFF)
.text:00000124 lw $v0, (puts & 0xFFFF)($gp)
.text:00000128 or $at, $zero
.text:0000012C move $t9, $v0
.text:00000130 jalr $t9
.text:00000134 or $at, $zero
.text:00000138 lw $gp, 0x20+var_10($fp)
.text:0000013C
.text:0000013C loc_13C: # CODE XREF: f_unsigned+34
.text:0000013C lw $v1, 0x20+arg_0($fp)
.text:00000140 lw $v0, 0x20+arg_4($fp)
.text:00000144 or $at, $zero
.text:00000148 bne $v1, $v0, loc_170
.text:0000014C or $at, $zero
.text:00000150 lui $v0, (aAB >> 16) # "a==b"
.text:00000154 addiu $a0, $v0, (aAB & 0xFFFF) # "a==b"
.text:00000158 lw $v0, (puts & 0xFFFF)($gp)
.text:0000015C or $at, $zero
.text:00000160 move $t9, $v0
.text:00000164 jalr $t9
.text:00000168 or $at, $zero
.text:0000016C lw $gp, 0x20+var_10($fp)
.text:00000170
.text:00000170 loc_170: # CODE XREF: f_unsigned+68
.text:00000170 lw $v1, 0x20+arg_0($fp)
.text:00000174 lw $v0, 0x20+arg_4($fp)