currently, aarch64 LEGITIMIZE_ADDRESS_P hook will reject all "reg + offset"
address given
"offset" is beyond supported range.
while this may be too strict. we should honor the "strict_p" parameter in
the hook. before
reload, we accept all offset if it's a frame access, because the offset may
change during
later register elimination.
the early reject of "reg + offset" may cause extra registers created, and if
that register
live range is across function invoking then callee saved reg needed, thus
introduce extra
reg save/restore also.
give a simple example as:
int
test15 (void)
{
unsigned char a[480];
initialize_array (a, 480);
if (a[0] == 0x10)
return 1;
return 0;
}
.S before the patch
(-O2 -fPIC)
===
test15:
sub sp, sp, #480
mov w1, 480
stp x29, x30, [sp, -32]!
add x29, sp, 0
str x19, [sp, 16]
add x19, x29, 32
mov x0, x19
bl initialize_array
ldrb w0, [x19]
ldr x19, [sp, 16]
ldp x29, x30, [sp], 32
cmp w0, 16
cset w0, eq
add sp, sp, 480
ret
.S after the patch
===
test15:
stp x29, x30, [sp, -496]!
mov w1, 480
add x29, sp, 0
add x0, x29, 16
bl initialize_array
ldrb w0, [x29, 16]
ldp x29, x30, [sp], 496
cmp w0, 16
cset w0, eq
ret
test done
=========
no regression on aarch64-none-elf bare metal.
bootstrap OK on aarch64.
OK for trunk?
thanks.
gcc/
* config/aarch64/aarch64.c (aarch64_classify_address): Accept all offset
for frame access
when strict_p is false.
gcc/testsuite
* gcc.target/aarch64/legitimize_stack_var_before_reload_1.c: New testcase.