hi,
I'm having some trouble while understanding the generated assembly
code for trampoline by mips back-end.
Following is the code for which i'm trying to undertsand the generated
trampoline code.
int foo(int (*f)()){
(*f)();
}
main(){
int i;
int g(){printf("hello,%d",i);}
foo(g);
}
Parts of generated assembly code which are confusing are
$LTRAMP0:
.word 0x03e00821 # move $1,$31
.word 0x04110001 # bgezal $0,.+8
.word 0x00000000 # nop
.word 0x8fe30014 # lw $3,20($31)
.word 0x8fe20018 # lw $2,24($31)
.word 0x0060c821 # move $25,$3 (abicalls)
.word 0x00600008 # jr $3
.word 0x0020f821 # move $31,$1
.word 0x00000000 # <function address>
.word 0x00000000 # <static chain value>
.globl _flush_cache
main:
- - - - - - - - - - - -
addiu $sp,$sp,-80
sw $31,72($sp)
sw $fp,68($sp)
sw $16,64($sp)
move $fp,$sp
addiu $2,$fp,20
addiu $16,$2,4
lui $2,%hi($LTRAMP0)
move $3,$16
addiu $2,$2,%lo($LTRAMP0)
li $5,40 # 0x28
move $4,$2
jal memcpy
nop
lui $2,%hi(g.1238)
addiu $2,$2,%lo(g.1238)
sw $2,32($16)
move $3,$16
li $4,40 # 0x28
li $5,3 # 0x3
jal _flush_cache
nop
addiu $2,$fp,20
addiu $2,$2,4
move $3,$2
jal foo
nop
A bit of explaination of above code will be helpful
