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IBM Z: stack clash prot: add missing updates of last_probe_offset

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After emitting probes in a loop last_probe_offset needs to be updated.
Not doing this usually assumes a too low distance to the last access
when emitting the remainder leading to stack probes being omitted.

gcc/ChangeLog:

2020-05-14  Andreas Krebbel  <krebbel@linux.ibm.com>

	* config/s390/s390.c (allocate_stack_space): Add missing updates
	of last_probe_offset.

gcc/testsuite/ChangeLog:

2020-05-14  Andreas Krebbel  <krebbel@linux.ibm.com>

	* gcc.target/s390/stack-clash-1.c: New test.
This commit is contained in:
Andreas Krebbel 2020-05-14 08:16:27 +02:00
parent d3e5bae174
commit 868d351e23
4 changed files with 29 additions and 0 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2020-05-14 Andreas Krebbel <krebbel@linux.ibm.com>
* config/s390/s390.c (allocate_stack_space): Add missing updates
of last_probe_offset.
2020-05-14 Andreas Krebbel <krebbel@linux.ibm.com>
* config/s390/s390.md ("allocate_stack"): Call

3
gcc/config/s390/s390.c
View file

@ -10996,6 +10996,8 @@ allocate_stack_space (rtx size, HOST_WIDE_INT last_probe_offset,
stack_pointer_rtx,
offset));
}
if (num_probes > 0)
last_probe_offset = INTVAL (offset);
dump_stack_clash_frame_info (PROBE_INLINE, residual != 0);
}
else
@ -11029,6 +11031,7 @@ allocate_stack_space (rtx size, HOST_WIDE_INT last_probe_offset,
s390_prologue_plus_offset (stack_pointer_rtx, temp_reg,
const0_rtx, true);
temp_reg_clobbered_p = true;
last_probe_offset = INTVAL (offset);
dump_stack_clash_frame_info (PROBE_LOOP, residual != 0);
}

4
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,7 @@
2020-05-14 Andreas Krebbel <krebbel@linux.ibm.com>
* gcc.target/s390/stack-clash-1.c: New test.
2020-05-14 Andreas Krebbel <krebbel@linux.ibm.com>
* gcc.target/s390/stack-clash-3.c: New test.

17
gcc/testsuite/gcc.target/s390/stack-clash-1.c Normal file
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@ -0,0 +1,17 @@
/* Make sure a stack probe is emitted also for the remaining bytes
after the loop probing the large chunk. */
/* { dg-do compile } */
/* { dg-options "-O2 -march=z9-ec -fstack-clash-protection" } */
void large_stack() {
volatile int stack[8000];
int i;
for (i = 0; i < sizeof(stack) / sizeof(int); ++i)
stack[i] = i;
}
/* We use a compare for the stack probe. There needs to be one inside
a loop and another for the remaining bytes. */
/* { dg-final { scan-assembler-times "cg\t" 2 { target lp64 } } } */
/* { dg-final { scan-assembler-times "c\t" 2 { target { ! lp64 } } } } */