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RE: [PATCH][GCC][AArch64] Cleanup the AArch64 testsuite when stack-clash is on [Patch (6/6)]


Hi James,

Thanks for the review.

> -----Original Message-----
> From: James Greenhalgh <james.greenhalgh@arm.com>
> Sent: Tuesday, July 31, 2018 22:07
> To: Tamar Christina <Tamar.Christina@arm.com>
> Cc: gcc-patches@gcc.gnu.org; nd <nd@arm.com>; Richard Earnshaw
> <Richard.Earnshaw@arm.com>; Marcus Shawcroft
> <Marcus.Shawcroft@arm.com>
> Subject: Re: [PATCH][GCC][AArch64] Cleanup the AArch64 testsuite when
> stack-clash is on [Patch (6/6)]
> 
> On Tue, Jul 24, 2018 at 05:28:03AM -0500, Tamar Christina wrote:
> > Hi All,
> >
> > This patch cleans up the testsuite when a run is done with stack clash
> > protection turned on.
> >
> > Concretely this switches off -fstack-clash-protection for a couple of tests:
> >
> > * sve: We don't yet support stack-clash-protection and sve, so for now turn
> these off.
> > * assembler scan: some tests are quite fragile in that they check for exact
> >        assembly output, e.g. check for exact amount of sub etc.  These won't
> >        match now.
> > * vla: Some of the ubsan tests negative array indices. Because the arrays
> weren't
> >        used before the incorrect $sp wouldn't have been used. The correct
> value is
> >        restored on ret.  Now however we probe the $sp which causes a
> segfault.
> > * params: When testing the parameters we have to skip these on AArch64
> because of our
> >           custom constraints on them.  We already test them separately so this
> isn't a
> >           loss.
> >
> > Note that the testsuite is not entire clean due to gdb failure caused
> > by alloca with stack clash. On AArch64 we output an incorrect .loc
> > directive, but this is already the case with the current implementation in
> GCC and is a bug unrelated to this patch series.
> >
> > Bootstrapped Regtested on aarch64-none-linux-gnu, x86_64-pc-linux-gnu
> and no issues.
> > Both targets were tested with stack clash on and off by default.
> >
> > Ok for trunk?
> 
> For each of the generic tests you skip because of mismatched bounds, I think
> we should ensure we have an equivalent test checking that behaviour in
> gcc.target/aarch64/ . If we have that, it might be good to cross-reference
> them with a comment above your skip lines.

The problem is, fundamentally what these two tests are trying to test we don't support.
pr82788.c is explicitly checking for a bug that happened when you have a 1KB probe interval
with a 4KB guard-size.

And stack-check-6a.c is checking that increasing the guard size with smaller probe interval reduces
the amount of probing you would have to do. 

Both these cases we can't support as we force stack guard to be the same as probing interval.  I can't
think of any equivalent AArch64 test as these class of failures just don't happen for us.

> 
> > * vla: Some of the ubsan tests negative array indices. Because the arrays
> weren't
> >        used before the incorrect $sp wouldn't have been used. The correct
> value is
> >        restored on ret.  Now however we probe the $sp which causes a
> segfault.
> 
> This is interesting behaviour; is it a desirable side effect of your changes?

They should fail for every correct implementation of stack clash protection.  The programs were always invalid.
These test could probably be made to work by allocating some number of stack space before the negative
Index arrays.  They wouldn't crash then as the negative indices would still keep you within your stack space,
but that's arguably a different test then.

> 
> Otherwise, this patch is OK.
> 
> Thanks,
> James
> 
> 
> > gcc/testsuite/
> > 2018-07-24  Tamar Christina  <tamar.christina@arm.com>
> >
> > 	PR target/86486
> > 	* gcc.dg/pr82788.c: Skip for AArch64.
> > 	* gcc.dg/guality/vla-1.c: Turn off stack-clash.
> > 	* gcc.target/aarch64/subsp.c: Likewise.
> > 	* gcc.target/aarch64/sve/mask_struct_load_3.c: Likewise.
> > 	* gcc.target/aarch64/sve/mask_struct_store_3.c: Likewise.
> > 	* gcc.target/aarch64/sve/mask_struct_store_4.c: Likewise.
> > 	* gcc.dg/params/blocksort-part.c: Skip stack-clash checks
> > 	on AArch64.
> > 	* gcc.dg/stack-check-10.c: Add AArch64 specific checks.
> > 	* gcc.dg/stack-check-5.c: Add AArch64 specific checks.
> > 	* gcc.dg/stack-check-6a.c: Skip on AArch64, we don't support this.
> > 	* testsuite/lib/target-supports.exp
> > 	(check_effective_target_frame_pointer_for_non_leaf): AArch64
> does not
> > 	require frame pointer for non-leaf functions.
> >
> > > -----Original Message-----
> > > From: Tamar Christina <tamar.christina@arm.com>
> > > Sent: Wednesday, July 11, 2018 12:23
> > > To: gcc-patches@gcc.gnu.org
> > > Cc: nd <nd@arm.com>; James Greenhalgh
> <James.Greenhalgh@arm.com>;
> > > Richard Earnshaw <Richard.Earnshaw@arm.com>; Marcus Shawcroft
> > > <Marcus.Shawcroft@arm.com>
> > > Subject: [PATCH][GCC][AArch64] Cleanup the AArch64 testsuite when
> > > stack- clash is on [Patch (6/6)]
> > >
> > > Hi All,
> > >
> > > This patch cleans up the testsuite when a run is done with stack
> > > clash protection turned on.
> > >
> > > Concretely this switches off -fstack-clash-protection for a couple of tests:
> > >
> > > * sve: We don't yet support stack-clash-protection and sve, so for
> > > now turn these off.
> > > * assembler scan: some tests are quite fragile in that they check for exact
> > >        assembly output, e.g. check for exact amount of sub etc.  These won't
> > >        match now.
> > > * vla: Some of the ubsan tests negative array indices. Because the
> > > arrays weren't
> > >        used before the incorrect $sp wouldn't have been used. The
> > > correct value is
> > >        restored on ret.  Now however we probe the $sp which causes a
> segfault.
> > > * params: When testing the parameters we have to skip these on
> > > AArch64 because of our
> > >           custom constraints on them.  We already test them
> > > separately so this isn't a
> > >           loss.
> > >
> > > Note that the testsuite is not entire clean due to gdb failure
> > > caused by alloca with stack clash. On AArch64 we output an incorrect
> > > .loc directive, but this is already the case with the current
> > > implementation in GCC and is a bug unrelated to this patch series.
> > >
> > > Bootstrapped Regtested on aarch64-none-linux-gnu,
> > > x86_64-pc-linux-gnu and no issues.
> > > Both targets were tested with stack clash on and off by default.
> > >
> > > Ok for trunk?
> > >
> > > Thanks,
> > > Tamar
> > >
> > > gcc/testsuite/
> > > 2018-07-11  Tamar Christina  <tamar.christina@arm.com>
> > >
> > > 	PR target/86486
> > > 	gcc.dg/pr82788.c: Skip for AArch64.
> > > 	gcc.dg/guality/vla-1.c: Turn off stack-clash.
> > > 	gcc.target/aarch64/subsp.c: Likewise.
> > > 	gcc.target/aarch64/sve/mask_struct_load_3.c: Likewise.
> > > 	gcc.target/aarch64/sve/mask_struct_store_3.c: Likewise.
> > > 	gcc.target/aarch64/sve/mask_struct_store_4.c: Likewise.
> > > 	gcc.dg/params/blocksort-part.c: Skip stack-clash checks
> > > 	on AArch64.
> > >
> > > --
> 
> > diff --git a/gcc/testsuite/c-c++-common/ubsan/vla-1.c
> > b/gcc/testsuite/c-c++-common/ubsan/vla-1.c
> > index
> >
> 52ade3aab7566dce3ca7ef931ac65895005d5e13..c97465edae195442a71ee66a
> b250
> > 15a2ac4fc8fc 100644
> > --- a/gcc/testsuite/c-c++-common/ubsan/vla-1.c
> > +++ b/gcc/testsuite/c-c++-common/ubsan/vla-1.c
> > @@ -1,5 +1,5 @@
> >  /* { dg-do run } */
> > -/* { dg-options "-fsanitize=vla-bound -Wall -Wno-unused-variable" }
> > */
> > +/* { dg-options "-fsanitize=vla-bound -Wall -Wno-unused-variable
> > +-fno-stack-clash-protection" } */
> >
> >  typedef long int V;
> >  int x = -1;
> > diff --git a/gcc/testsuite/gcc.dg/params/blocksort-part.c
> > b/gcc/testsuite/gcc.dg/params/blocksort-part.c
> > index
> >
> a9154f2e61ccd21b60153f20be3891b988f9ef2c..1e677878e7bd9c68b026f8c72b
> 0d
> > e9f01e15459c 100644
> > --- a/gcc/testsuite/gcc.dg/params/blocksort-part.c
> > +++ b/gcc/testsuite/gcc.dg/params/blocksort-part.c
> > @@ -1,3 +1,4 @@
> > +/* { dg-skip-if "AArch64 does not support these bounds." {
> > +aarch64*-*-* } { "--param stack-clash-protection-*" } } */
> >
> >  /*-------------------------------------------------------------*/
> >  /*--- Block sorting machinery                               ---*/
> > diff --git a/gcc/testsuite/gcc.dg/pr82788.c
> > b/gcc/testsuite/gcc.dg/pr82788.c index
> >
> a8f628fd7f66c3e56739f6ff491df38b23f4d4df..41c442f61a625c8b350e1e4c870a
> > 98d86b167031 100644
> > --- a/gcc/testsuite/gcc.dg/pr82788.c
> > +++ b/gcc/testsuite/gcc.dg/pr82788.c
> > @@ -1,4 +1,5 @@
> >  /* { dg-do run } */
> >  /* { dg-options "-O2 -fstack-clash-protection --param
> > stack-clash-protection-probe-interval=10 --param
> > stack-clash-protection-guard-size=12" } */
> >  /* { dg-require-effective-target supports_stack_clash_protection } */
> > +/* { dg-skip-if "AArch64 does not support this interval." {
> > +aarch64*-*-* } } */
> >  int main() { int a[1442]; return 0;}
> > diff --git a/gcc/testsuite/gcc.dg/stack-check-10.c
> > b/gcc/testsuite/gcc.dg/stack-check-10.c
> > index
> >
> a86956ad6925464e4a938a33e609fae5004201c7..2f5a090cb7a4ed6d2e6e43174
> 921
> > 50a348a326ab 100644
> > --- a/gcc/testsuite/gcc.dg/stack-check-10.c
> > +++ b/gcc/testsuite/gcc.dg/stack-check-10.c
> > @@ -39,3 +39,4 @@ f3 (void)
> >     need a frame pointer.  Otherwise neither should.  */
> >  /* { dg-final { scan-rtl-dump-times "Stack clash no frame pointer
> > needed" 2 "pro_and_epilogue" { target { ! frame_pointer_for_non_leaf }
> > } } } */
> >  /* { dg-final { scan-rtl-dump-times "Stack clash frame pointer
> > needed" 2 "pro_and_epilogue" { target { frame_pointer_for_non_leaf } }
> > } } */
> > +/* { dg-final { scan-rtl-dump-times "Stack clash no probe small stack
> > +adjustment in prologue" 2 "pro_and_epilogue" { target { aarch64*-*-*
> > +} } } } */
> > diff --git a/gcc/testsuite/gcc.dg/stack-check-5.c
> > b/gcc/testsuite/gcc.dg/stack-check-5.c
> > index
> >
> 604fa3cf6c5b502f74c1e3497b3b8d72a15bb3ea..0243147939c10e8f4632520b12
> 71
> > 4724af85b332 100644
> > --- a/gcc/testsuite/gcc.dg/stack-check-5.c
> > +++ b/gcc/testsuite/gcc.dg/stack-check-5.c
> > @@ -66,7 +66,9 @@ f3 (void)
> >  /* { dg-final { scan-rtl-dump-times "Stack clash no frame pointer
> > needed" 4 "pro_and_epilogue" { target { ! frame_pointer_for_non_leaf }
> > } } } */
> >  /* { dg-final { scan-rtl-dump-times "Stack clash no frame pointer
> > needed" 2 "pro_and_epilogue" { target { frame_pointer_for_non_leaf } }
> > } } */
> >  /* { dg-final { scan-rtl-dump-times "Stack clash frame pointer
> > needed" 2 "pro_and_epilogue" { target { frame_pointer_for_non_leaf } }
> > } } */
> > -
> > +/* AArch64 won't require a probe here due to the allocation amount
> > +being less than 1KB.  */
> > +/* { dg-final { scan-rtl-dump-times "Stack clash no probe small stack
> > +adjustment in prologue" 3 "pro_and_epilogue" { target { aarch64*-*-*
> > +} } } } */
> > +/* { dg-final { scan-rtl-dump-times "Stack clash no probe no stack
> > +adjustment in prologue" 1 "pro_and_epilogue" { target { aarch64*-*-*
> > +} } } } */
> >
> >  /* We have selected the size of the array in f2/f3 to be large enough
> >     to not live in the red zone on targets that support it.
> > diff --git a/gcc/testsuite/gcc.dg/stack-check-6a.c
> > b/gcc/testsuite/gcc.dg/stack-check-6a.c
> > index
> >
> 8fb9c621585957a85877ebadfbc4a8daabe4311c..68dd9bc48a0c26ecb84ddd2c0
> 9b8
> > aa74d3276695 100644
> > --- a/gcc/testsuite/gcc.dg/stack-check-6a.c
> > +++ b/gcc/testsuite/gcc.dg/stack-check-6a.c
> > @@ -5,6 +5,7 @@
> >  /* { dg-options "-O2 -fstack-clash-protection
> > -fdump-rtl-pro_and_epilogue -fno-optimize-sibling-calls --param
> > stack-clash-protection-probe-interval=12 --param
> > stack-clash-protection-guard-size=16" } */
> >  /* { dg-require-effective-target supports_stack_clash_protection  }
> > */
> >  /* { dg-skip-if "" { *-*-* } { "-fstack-protector*" } { "" } } */
> > +/* { dg-skip-if "" { aarch64*-*-* } } */
> >
> >
> >  #include "stack-check-6.c"
> > diff --git a/gcc/testsuite/gcc.target/aarch64/subsp.c
> > b/gcc/testsuite/gcc.target/aarch64/subsp.c
> > index
> >
> 70d848c59d1f1e4df4314ca012c7a5d9d3b91ebc..6ef6b2c90ae694055749a94b6
> 8cb
> > ba5ee4aea882 100644
> > --- a/gcc/testsuite/gcc.target/aarch64/subsp.c
> > +++ b/gcc/testsuite/gcc.target/aarch64/subsp.c
> > @@ -1,4 +1,4 @@
> > -/* { dg-options "-O" } */
> > +/* { dg-options "-O -fno-stack-clash-protection" } */
> >
> >  int foo (void *);
> >
> > diff --git a/gcc/testsuite/gcc.target/aarch64/sve/mask_struct_load_3.c
> > b/gcc/testsuite/gcc.target/aarch64/sve/mask_struct_load_3.c
> > index
> >
> 29702ab55f249c3ebd0baf44981870524098e1e4..baeec61bb59aff56f0dcc20fc6
> ec
> > 6b93d517490e 100644
> > --- a/gcc/testsuite/gcc.target/aarch64/sve/mask_struct_load_3.c
> > +++ b/gcc/testsuite/gcc.target/aarch64/sve/mask_struct_load_3.c
> > @@ -1,5 +1,5 @@
> >  /* { dg-do compile } */
> > -/* { dg-options "-O2 -ftree-vectorize -ffast-math" } */
> > +/* { dg-options "-O2 -ftree-vectorize -ffast-math
> > +-fno-stack-clash-protection" } */
> >
> >  #include <stdint.h>
> >
> > diff --git
> > a/gcc/testsuite/gcc.target/aarch64/sve/mask_struct_store_3.c
> > b/gcc/testsuite/gcc.target/aarch64/sve/mask_struct_store_3.c
> > index
> >
> 001f5be8ff58bfcc75eccc4c050bef1e53faffeb..eae3be7a7b24dc124f7c1c26a97f
> > b25400cc62d2 100644
> > --- a/gcc/testsuite/gcc.target/aarch64/sve/mask_struct_store_3.c
> > +++ b/gcc/testsuite/gcc.target/aarch64/sve/mask_struct_store_3.c
> > @@ -1,5 +1,5 @@
> >  /* { dg-do compile } */
> > -/* { dg-options "-O2 -ftree-vectorize -ffast-math" } */
> > +/* { dg-options "-O2 -ftree-vectorize -ffast-math
> > +-fno-stack-clash-protection" } */
> >
> >  #include <stdint.h>
> >
> > diff --git
> > a/gcc/testsuite/gcc.target/aarch64/sve/mask_struct_store_4.c
> > b/gcc/testsuite/gcc.target/aarch64/sve/mask_struct_store_4.c
> > index
> >
> 59e9ee49c4a214b731ed1975da0dcfa46c059f8b..ce9825f73e8495a7f5c1f4ab1d
> 5b
> > f1aaf5035e17 100644
> > --- a/gcc/testsuite/gcc.target/aarch64/sve/mask_struct_store_4.c
> > +++ b/gcc/testsuite/gcc.target/aarch64/sve/mask_struct_store_4.c
> > @@ -1,5 +1,5 @@
> >  /* { dg-do compile } */
> > -/* { dg-options "-O2 -ftree-vectorize -ffast-math" } */
> > +/* { dg-options "-O2 -ftree-vectorize -ffast-math
> > +-fno-stack-clash-protection" } */
> >
> >  #include <stdint.h>
> >
> > diff --git a/gcc/testsuite/lib/target-supports.exp
> > b/gcc/testsuite/lib/target-supports.exp
> > index
> >
> 7ec350213e9225ad342d030afac30bd613851aa1..5624f361c59b97cb967b3485a
> dc8
> > db01da048a84 100644
> > --- a/gcc/testsuite/lib/target-supports.exp
> > +++ b/gcc/testsuite/lib/target-supports.exp
> > @@ -9280,10 +9280,6 @@ proc
> > check_effective_target_supports_stack_clash_protection { } {  # Return
> > 1 if the target creates a frame pointer for non-leaf functions  # Note we
> ignore cases where we apply tail call optimization here.
> >  proc check_effective_target_frame_pointer_for_non_leaf { } {
> > -  if { [istarget aarch*-*-*] } {
> > -	return 1
> > -  }
> > -
> >    # Solaris/x86 defaults to -fno-omit-frame-pointer.
> >    if { [istarget i?86-*-solaris*] || [istarget x86_64-*-solaris*] } {
> >      return 1
> >


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