https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89208
Bug ID: 89208
Summary: unaligned access expanded to memcpy
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: bernd.edlinger at hotmail dot de
Target Milestone: ---
This test case is mis-compiled:
$ cat unaligned-argument-3.c
/* { dg-do compile } */
/* { dg-options "-ffreestanding -marm -march=armv6 -mno-unaligned-access
-mfloat-abi=soft -mabi=aapcs -O3" } */
struct s {
int a, b;
} __attribute__((packed));
void f(struct s *a, struct s *b)
{
*a = *b;
}
/* { dg-final { scan-assembler-times "ldrd" 0 } } */
/* { dg-final { scan-assembler-times "strd" 0 } } */
/* { dg-final { scan-assembler-times "ldm" 0 } } */
/* { dg-final { scan-assembler-times "stm" 0 } } */
/* { dg-final { scan-assembler-times "memcpy" 0 } } */
$ arm-linux-gnueabihf-gcc -ffreestanding -marm -march=armv6
-mno-unaligned-access -mfloat-abi=soft -mabi=aapcs -O3 -S
unaligned-argument-3.c
$ $ cat unaligned-argument-3.s
.arch armv6
.eabi_attribute 20, 1
.eabi_attribute 21, 1
.eabi_attribute 23, 3
.eabi_attribute 24, 1
.eabi_attribute 25, 1
.eabi_attribute 26, 1
.eabi_attribute 30, 2
.eabi_attribute 34, 0
.eabi_attribute 18, 4
.file "unaligned-argument-3.c"
.text
.align 2
.global f
.syntax unified
.arm
.fpu softvfp
.type f, %function
f:
@ args = 0, pretend = 0, frame = 0
@ frame_needed = 0, uses_anonymous_args = 0
mov r2, #8
push {r4, lr}
bl memcpy
pop {r4, pc}
.size f, .-f
.ident "GCC: (GNU) 9.0.1 20190128 (experimental)"
.section .note.GNU-stack,"",%progbits
it is wrong to call memcpy if -ffreestanding is used.
