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[AARCH64] make stdarg functions work with +nofp

Message ID CABXYE2V+SwMbT5EsYM6hD0ENjwAhsZKAPTLvDuLxCNX9GAhLvg@mail.gmail.com
State New
Headers show

Commit Message

Jim Wilson May 22, 2015, 11:24 p.m. UTC 
The compiler currently ICEs when compiling a stdarg function with
+nofp, as reported in PR 66258.

The aarch64.md file disables FP instructions using TARGET_FLOAT, which
supports both -mgeneral-regs-only and +nofp.  But there is code in
aarch64.c that checks TARGET_GENERAL_REGS_ONLY.  This results in FP
instructions when using +nofp,  The aarch64.c code needs to use
TARGET_FLOAT instead like the md file already does.

I can't meaningfully test this with a bootstrap, since the patch has
no effect unless I bootstrap with +nofp, and that will fail as gcc
contains floating point code.

The testsuite already has multiple stdarg tests, so there is no need
for another one.

I tested this by verifying I get the same results for some simple
testcasess with and without the patch, with and without using
-mgeneral-regs-only and -mcpu=cortex-a53+nofp.

Comments

Jim Wilson June 9, 2015, 2:18 a.m. UTC | #1 
On Tue, Jun 2, 2015 at 3:45 AM, James Greenhalgh
<james.greenhalgh@arm.com> wrote:
> On Tue, Jun 02, 2015 at 11:38:29AM +0100, Kyrill Tkachov wrote:
>> Hi James, Jim,
>>
>> On 02/06/15 10:42, James Greenhalgh wrote:
>> > On Sat, May 23, 2015 at 12:24:00AM +0100, Jim Wilson wrote:
>> >> The compiler currently ICEs when compiling a stdarg function with
>> >> +nofp, as reported in PR 66258.

I'd like approval to add this patch to the gcc-5 release branch.  I
got two requests for this in the PR as currently grub won't build with
gcc-5.1.  I tested the patch on the gcc-5-release branch with a
default languages bootstrap and make check on an APM box running
Ubuntu.  I also verified that the patch fixes my testcase.

Jim
Jim Wilson June 16, 2015, 8:27 p.m. UTC | #2 
On Tue, Jun 16, 2015 at 1:46 AM, James Greenhalgh
<james.greenhalgh@arm.com> wrote:
> I'm happy for this to be backported.

Thanks.  Applied.

> I think Grub probably wants to change if they want to be safe, from
> what I've read it looks like they are hoping to use something like a
> standard printf without touching the FP registers, which is suspect...

Grub has its own printf code, as it can't use glibc, and the
grub_printf function doesn't support FP format codes.  So this should
not be a problem for grub.

FYI In the git tree, grub changed from using +nofp to
-mgeneral-regs-only on June 2, because the kernel uses
-mgeneral-regs-only, and because +nofp was broken in gcc-5-branch.
But we still needed the patch backported for people who could not or
didn't want to upgrade grub.

Jim
diff mbox

Patch

2015-05-22  Jim Wilson  <jim.wilson@linaro.org>

	PR target/66258
	* config/aarch64/aarch64.c (aarch64_function_value_regno_p): Change
	!TARGET_GENERAL_REGS_ONLY to TARGET_FLOAT.
	(aarch64_secondary_reload): Likewise
	(aarch64_expand_builtin_va_start): Change TARGET_GENERAL_REGS_ONLY
	to !TARGET_FLOAT.
	(aarch64_gimplify_va_arg_expr, aarch64_setup_incoming_varargs):
	Likewise.

Index: config/aarch64/aarch64.c
===================================================================
--- config/aarch64/aarch64.c	(revision 223590)
+++ config/aarch64/aarch64.c	(working copy)
@@ -1666,7 +1666,7 @@  aarch64_function_value_regno_p (const un
   /* Up to four fp/simd registers can return a function value, e.g. a
      homogeneous floating-point aggregate having four members.  */
   if (regno >= V0_REGNUM && regno < V0_REGNUM + HA_MAX_NUM_FLDS)
-    return !TARGET_GENERAL_REGS_ONLY;
+    return TARGET_FLOAT;
 
   return false;
 }
@@ -4783,7 +4783,7 @@  aarch64_secondary_reload (bool in_p ATTR
   /* A TFmode or TImode memory access should be handled via an FP_REGS
      because AArch64 has richer addressing modes for LDR/STR instructions
      than LDP/STP instructions.  */
-  if (!TARGET_GENERAL_REGS_ONLY && rclass == GENERAL_REGS
+  if (TARGET_FLOAT && rclass == GENERAL_REGS
       && GET_MODE_SIZE (mode) == 16 && MEM_P (x))
     return FP_REGS;
 
@@ -7571,7 +7571,7 @@  aarch64_expand_builtin_va_start (tree va
   vr_save_area_size
     = (NUM_FP_ARG_REGS - cum->aapcs_nvrn) * UNITS_PER_VREG;
 
-  if (TARGET_GENERAL_REGS_ONLY)
+  if (!TARGET_FLOAT)
     {
       if (cum->aapcs_nvrn > 0)
 	sorry ("%qs and floating point or vector arguments",
@@ -7681,7 +7681,7 @@  aarch64_gimplify_va_arg_expr (tree valis
 					       &is_ha))
     {
       /* TYPE passed in fp/simd registers.  */
-      if (TARGET_GENERAL_REGS_ONLY)
+      if (!TARGET_FLOAT)
 	sorry ("%qs and floating point or vector arguments",
 	       "-mgeneral-regs-only");
 
@@ -7918,7 +7918,7 @@  aarch64_setup_incoming_varargs (cumulati
   gr_saved = NUM_ARG_REGS - local_cum.aapcs_ncrn;
   vr_saved = NUM_FP_ARG_REGS - local_cum.aapcs_nvrn;
 
-  if (TARGET_GENERAL_REGS_ONLY)
+  if (!TARGET_FLOAT)
     {
       if (local_cum.aapcs_nvrn > 0)
 	sorry ("%qs and floating point or vector arguments",