On Sun, Oct 4, 2015 at 5:26 PM, Uros Bizjak <ubiz...@gmail.com> wrote:
> As shown in PR 66697 [1] and WineHQ bug [2], an application can
> misalign incoming stack to less than ABI mandated 16 bytes. While it
> is possible to use -mincoming-stack-boundary=2 (= 4 bytes) for 32 bit
> targets to emit stack realignment code, this option is artificially
> limited to 4 (= 16 bytes) for 64bit targets.
Attached v2 patch goes all the way to enable -mstackrealign and
'force_align_arg_pointer' attribute for x86_64. In addition to
-mincoming-stack-boundary changes, the patch changes
MIN_STACK_BOUNDARY definition to 8bytes on 64bit targets, as this is
really the minimum supported stack boundary.
This patch is also needed to allow stack realignment in the interrupt handler.
2015-10-05 Uros Bizjak <ubiz...@gmail.com>
PR target/66697
* config/i386/i386.h (MIN_STACK_BOUNDARY): Redefine as BITS_PER_WORD.
* config/i386/i386.c (ix86_option_override_internal): Lower minimum
allowed incoming stack boundary to 3 for 64bit SSE targets.
(ix86_minimum_incoming_stack_boundary): Also initialize
incoming_stack_boundary to MIN_STACK_BOUNDARY for 64bit targets
when -mstackrealign or force_align_arg_pointer attribute is used.
(ix86_handle_force_align_arg_pointer_attribute): New function.
(ix86_attribute_table): Use it for force_align_arg_pointer attribute.
testsuite/ChangeLog:
2015-10-05 Uros Bizjak <ubiz...@gmail.com>
PR target/66697
* gcc.target/i386/20060512-1.c: Also run on 64bit targets.
(PUSH, POP): New defines.
(sse2_test): Use PUSH and POP to misalign runtime stack.
* gcc.target/i386/20060512-2.c: Also compile on 64bit targets.
Patch was bootstrapped and regression tested on x86_64-linux-gnu
{,-m32}. I plan to commit this patch to SVN tomorrow, and also to
backport the patch to gcc-5 branch, but no soon that a couple of weeks
without problems in mainline, and after receiving confirmation from
Cygwin people that the patch cures their problems.
Uros.
Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c (revision 228488)
+++ config/i386/i386.c (working copy)
@@ -5102,8 +5102,7 @@ ix86_option_override_internal (bool main_args_p,
ix86_incoming_stack_boundary = ix86_default_incoming_stack_boundary;
if (opts_set->x_ix86_incoming_stack_boundary_arg)
{
- int min = (TARGET_64BIT_P (opts->x_ix86_isa_flags)
- ? (TARGET_SSE_P (opts->x_ix86_isa_flags) ? 4 : 3) : 2);
+ int min = TARGET_64BIT_P (opts->x_ix86_isa_flags) ? 3 : 2;
if (opts->x_ix86_incoming_stack_boundary_arg < min
|| opts->x_ix86_incoming_stack_boundary_arg > 12)
@@ -11779,6 +11778,25 @@ find_drap_reg (void)
}
}
+/* Handle a "force_align_arg_pointer" attribute. */
+
+static tree
+ix86_handle_force_align_arg_pointer_attribute (tree *node, tree name,
+ tree, int, bool *no_add_attrs)
+{
+ if (TREE_CODE (*node) != FUNCTION_TYPE
+ && TREE_CODE (*node) != METHOD_TYPE
+ && TREE_CODE (*node) != FIELD_DECL
+ && TREE_CODE (*node) != TYPE_DECL)
+ {
+ warning (OPT_Wattributes, "%qE attribute only applies to functions",
+ name);
+ *no_add_attrs = true;
+ }
+
+ return NULL_TREE;
+}
+
/* Return minimum incoming stack alignment. */
static unsigned int
@@ -11789,11 +11807,10 @@ ix86_minimum_incoming_stack_boundary (bool sibcall
/* Prefer the one specified at command line. */
if (ix86_user_incoming_stack_boundary)
incoming_stack_boundary = ix86_user_incoming_stack_boundary;
- /* In 32bit, use MIN_STACK_BOUNDARY for incoming stack boundary
+ /* Use MIN_STACK_BOUNDARY for incoming stack boundary
if -mstackrealign is used, it isn't used for sibcall check and
estimated stack alignment is 128bit. */
else if (!sibcall
- && !TARGET_64BIT
&& ix86_force_align_arg_pointer
&& crtl->stack_alignment_estimated == 128)
incoming_stack_boundary = MIN_STACK_BOUNDARY;
@@ -48050,7 +48067,7 @@ static const struct attribute_spec ix86_attribute_
true },
/* force_align_arg_pointer says this function realigns the stack at entry.
*/
{ (const char *)&ix86_force_align_arg_pointer_string, 0, 0,
- false, true, true, ix86_handle_cconv_attribute, false },
+ false, true, true, ix86_handle_force_align_arg_pointer_attribute, false },
#if TARGET_DLLIMPORT_DECL_ATTRIBUTES
{ "dllimport", 0, 0, false, false, false, handle_dll_attribute, false },
{ "dllexport", 0, 0, false, false, false, handle_dll_attribute, false },
Index: config/i386/i386.h
===================================================================
--- config/i386/i386.h (revision 228488)
+++ config/i386/i386.h (working copy)
@@ -752,7 +752,7 @@ extern const char *host_detect_local_cpu (int argc
#define MAIN_STACK_BOUNDARY (TARGET_64BIT ? 128 : 32)
/* Minimum stack boundary. */
-#define MIN_STACK_BOUNDARY (TARGET_64BIT ? (TARGET_SSE ? 128 : 64) : 32)
+#define MIN_STACK_BOUNDARY BITS_PER_WORD
/* Boundary (in *bits*) on which the stack pointer prefers to be
aligned; the compiler cannot rely on having this alignment. */
Index: testsuite/gcc.target/i386/20060512-1.c
===================================================================
--- testsuite/gcc.target/i386/20060512-1.c (revision 228488)
+++ testsuite/gcc.target/i386/20060512-1.c (working copy)
@@ -1,5 +1,4 @@
/* { dg-do run } */
-/* { dg-require-effective-target ia32 } */
/* { dg-options "-std=gnu99 -msse2 -mpreferred-stack-boundary=4" } */
/* { dg-require-effective-target sse2 } */
@@ -7,6 +6,14 @@
#include <emmintrin.h>
+#ifdef __x86_64__
+# define PUSH "pushq %rsi"
+# define POP "popq %rsi"
+#else
+# define PUSH "pushl %esi"
+# define POP "popl %esi"
+#endif
+
__m128i __attribute__ ((__noinline__))
vector_using_function ()
{
@@ -27,9 +34,9 @@ static void
sse2_test (void)
{
int result;
- asm ("pushl %esi"); /* Disalign runtime stack. */
+ asm (PUSH); /* Misalign runtime stack. */
result = self_aligning_function (g_1, g_2);
if (result != 42)
abort ();
- asm ("popl %esi");
+ asm (POP);
}
Index: testsuite/gcc.target/i386/20060512-2.c
===================================================================
--- testsuite/gcc.target/i386/20060512-2.c (revision 228488)
+++ testsuite/gcc.target/i386/20060512-2.c (working copy)
@@ -1,5 +1,4 @@
/* { dg-do compile } */
-/* { dg-require-effective-target ia32 } */
/* { dg-options "-std=gnu99 -mpreferred-stack-boundary=4" } */
int
outer_function (int x, int y)
