On 8/15/19 9:47 PM, Bernd Edlinger wrote:
> Hi,
>
> this is the split out part from the "Fix not 8-byte aligned ldrd/strd on
> ARMv5 (PR 89544)"
> which is sanitizing the middle-end interface to the back-end for strict
> alignment,
> and a couple of bug-fixes that are necessary to survive boot-strap.
> It is intended to be applied after the PR 89544 fix.
>
> I think it would be possible to change the default implementation of
> STACK_SLOT_ALIGNMENT
> to make all stack variables always naturally aligned instead of doing that
> only
> in assign_parm_setup_stack, but would still like to avoid changing too many
> things
> that do not seem to have a problem. Since this would affect many targets,
> and more
> kinds of variables that may probably not have a strict alignment problem.
> But I am ready to take your advice though.
>
>
> Boot-strapped and reg-tested on x86_64-pc-linux-gnu and arm-linux-gnueabihf
> Is it OK for trunk?
>
>
Hmm, actually the hunk in assign_parm_setup_stack is not only failing
an assertion, but rather a wrong code bug:
I found now a test case that generates silently wrong code and is fixed
by this patch.
$ cat unaligned-argument-3.c
/* { dg-do compile } */
/* { dg-require-effective-target arm_arm_ok } */
/* { dg-options "-marm -mno-unaligned-access -O3" } */
typedef int __attribute__((aligned(1))) s;
void x(char*, s*);
void f(char a, s f)
{
x(&a, &f);
}
/* { dg-final { scan-assembler-times "str\t\[^\\n\]*\\\[sp\\\]" 1 } } */
/* { dg-final { scan-assembler-times "str\t\[^\\n\]*\\\[sp, #3\\\]" 0 } } */
currently with -marm -mno-unaligned-access -O3 we generate:
f:
@ args = 0, pretend = 0, frame = 8
@ frame_needed = 0, uses_anonymous_args = 0
str lr, [sp, #-4]!
sub sp, sp, #12
mov r3, r0
str r1, [sp, #3] <- may trap
add r0, sp, #7
add r1, sp, #3
strb r3, [sp, #7]
bl x
add sp, sp, #12
@ sp needed
ldr pc, [sp], #4
So I would like to add a test case to the patch as attached.
Tested with a cross, that both dg-final fail currently and are fixed
with the other patches applied.
Is it OK for trunk?
Thanks
Bernd.
2019-08-17 Bernd Edlinger <[email protected]>
PR middle-end/89544
* gcc.target/arm/unaligned-argument-3.c: New test.
Index: gcc/testsuite/gcc.target/arm/unaligned-argument-3.c
===================================================================
--- gcc/testsuite/gcc.target/arm/unaligned-argument-3.c (revision 0)
+++ gcc/testsuite/gcc.target/arm/unaligned-argument-3.c (working copy)
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target arm_arm_ok } */
+/* { dg-options "-marm -mno-unaligned-access -O3" } */
+
+typedef int __attribute__((aligned(1))) s;
+
+void x(char*, s*);
+void f(char a, s f)
+{
+ x(&a, &f);
+}
+
+/* { dg-final { scan-assembler-times "str\t\[^\\n\]*\\\[sp\\\]" 1 } } */
+/* { dg-final { scan-assembler-times "str\t\[^\\n\]*\\\[sp, #3\\\]" 0 } } */
