https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105830
Bug ID: 105830
Summary: call to memcpy when -nostdlib -nodefaultlibs flags
provided
Product: gcc
Version: 12.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: hiraditya at msn dot com
Target Milestone: ---
https://godbolt.org/z/jTEa6ajn3
```
// test.c
// Type your code here, or load an example.
/* Nonzero if either X or Y is not aligned on a "long" boundary. */
#define UNALIGNED(X, Y) \
(((unsigned long)X & (sizeof (unsigned long) - 1)) | ((unsigned long)Y &
(sizeof (unsigned long) - 1)))
#define UNALIGNED1(a) \
((unsigned long)(a) & (sizeof(unsigned long)-1))
/* How many bytes are copied each iteration of the 4X unrolled loop. */
#define BIGBLOCKSIZE (sizeof (unsigned long) * 4)
/* How many bytes are copied each iteration of the word copy loop. */
#define LITTLEBLOCKSIZE (sizeof (unsigned long))
/* Threshhold for punting to the byte copier. */
#define TOO_SMALL(LEN) ((LEN) < BIGBLOCKSIZE)
void * memcpy (void *__restrict dst0,
const void *__restrict src0,
unsigned long len0)
{
unsigned char *dst = dst0;
const unsigned char *src = src0;
/* If the size is small, or either SRC or DST is unaligned,
then punt into the byte copy loop. This should be rare. */
if (len0 >= LITTLEBLOCKSIZE && !UNALIGNED (src, dst))
{
unsigned long *aligned_dst;
const unsigned long *aligned_src;
aligned_dst = (unsigned long*)dst;
aligned_src = (const unsigned long*)src;
/* Copy one long word at a time if possible. */
/* Copy one long word at a time if possible. */
do
{
*aligned_dst++ = *aligned_src++;
len0 -= LITTLEBLOCKSIZE;
} while (len0 >= LITTLEBLOCKSIZE);
/* Pick up any residual with a byte copier. */
dst = (unsigned char*)aligned_dst;
src = (const unsigned char*)aligned_src;
}
for (; len0; len0--)
*dst++ = *src++;
return dst0;
}
// ARM gcc trunk
gcc -O3 -nostdlib -nodefaultlibs -S -o -
memcpy:
push {r3, r4, r5, r6, r7, lr}
cmp r2, #3
mov r4, r2
mov r5, r0
mov r6, r1
bls .L5
orr r3, r0, r1
lsls r3, r3, #30
beq .L9
.L3:
mov r2, r4
mov r1, r6
bl memcpy ; <------------- call to memcpy
mov r0, r5
pop {r3, r4, r5, r6, r7, pc}
.L9:
subs r7, r2, #4
and r4, r2, #3
bic r7, r7, #3
adds r7, r7, #4
mov r2, r7
add r6, r6, r7
bl memcpy ; <------------- call to memcpy
adds r0, r5, r7
.L5:
cmp r4, #0
bne .L3
mov r0, r5
pop {r3, r4, r5, r6, r7, pc}
