The following code snippet is the first few assembly instructions of a function.
The code runs on armv8a.
SUB SP, SP, #0x170 is the first assembly instruction of the function. Please note the instruction, FCMP S0, #0.0 .
My question is, register S0 is used without initialization. How is this possible?
Is there any assembly instruction that implicitly modifies S0 ?
.text:00000000000CDCF0 SUB SP, SP, #0x170
.text:00000000000CDCF4 MOV X2, #1
.text:00000000000CDCF8 MOV X3, X2
.text:00000000000CDCFC STR D8, [SP,#0x170+var_120]
.text:00000000000CDD00 STP X23, X24, [SP,#0x170+var_150]
.text:00000000000CDD04 MOV X23, X0
.text:00000000000CDD08 MOV X0, #0
.text:00000000000CDD0C STP X21, X22, [SP,#0x170+var_160]
.text:00000000000CDD10 STP X19, X20, [SP,#0x170+var_170]
.text:00000000000CDD14 STP X25, X26, [SP,#0x170+var_140]
.text:00000000000CDD18 STP X27, X30, [SP,#0x170+var_130]
.text:00000000000CDD1C ADD X21, SP, #0x170+var_10
.text:00000000000CDD20 ADD X22, SP, #0x170+var_8
.text:00000000000CDD24 LDRSW X1, [X23,#0x40]
.text:00000000000CDD28 MOV X4, X21
.text:00000000000CDD2C MOV X5, X22
.text:00000000000CDD30 BL GOMP_loop_dynamic_start
.text:00000000000CDD34 UXTB W0, W0
.text:00000000000CDD38 CBZ W0, loc_CE0B8
.text:00000000000CDD3C FMOV S8, #1.0
.text:00000000000CDD40 loc_CDD40 ;
.text:00000000000CDD40 LDR X24, [SP,#0x170+var_10]
.text:00000000000CDD44 LDR W20, [SP,#0x170+var_8]
.text:00000000000CDD48 LSL W26, W24, #0xC
.text:00000000000CDD4C MOV W27, W24
.text:00000000000CDD50 SBFIZ X26, X26, #2, #0x20 ; ' '
.text:00000000000CDD54 SBFIZ X24, X24, #2, #0x20 ; ' '
.text:00000000000CDD58
.text:00000000000CDD58 LDR W4, [X23,#0x3C]
.text:00000000000CDD5C LDR X3, [X23]
.text:00000000000CDD60 LDR X2, [X23,#8]
.text:00000000000CDD64 SXTW X25, W4
.text:00000000000CDD68 LDR X5, [X23,#0x10]
.text:00000000000CDD6C LSL X1, X25, #4
.text:00000000000CDD70 LDRSW X6, [X23,#0x38]
.text:00000000000CDD74 SUB X7, X1, X25
.text:00000000000CDD78 LDR W9, [X3,X24]
.text:00000000000CDD7C LDR W11, [X2,X24]
.text:00000000000CDD80 ADD X10, X7, X6
.text:00000000000CDD84 LDR W8, [X5,W4,SXTW#2]
.text:00000000000CDD88 SUB W14, W9, #0x20 ; ' '
.text:00000000000CDD8C LDR X13, [X23,#0x18]
.text:00000000000CDD90 SUB W15, W11, #0x20 ; ' '
.text:00000000000CDD94 LDR X19, [X23,#0x28]
.text:00000000000CDD98 MOV W3, W8
.text:00000000000CDD9C LDR X12, [X23,#0x30]
.text:00000000000CDDA0 MADD W16, W8, W15, W14
.text:00000000000CDDA4 LDR X17, [X13,X10,LSL#3]
.text:00000000000CDDA8 ADD X19, X19, X26
.text:00000000000CDDAC LDR X1, [X23,#0x20]
.text:00000000000CDDB0 MOV X2, X19
.text:00000000000CDDB4 ADD X25, X12, X24
.text:00000000000CDDB8 ADD X0, X17, W16,SXTW
.text:00000000000CDDBC BL FftCorr1
.text:00000000000CDDC0 FCMP S0, #0.0
