------- Comment #3 from ubizjak at gmail dot com 2009-08-06 10:47 -------
Hm, we can fix this by teaching scheduler that every access to %mm registers
clobbers FP state. Since scheduler already depend all x87 instructions on
Top-Of-Stack (TOS) register, we can perhaps extend this requirement for all
instructions that use %mm reg.
Something like the proof-of-concept patch bellow:
--cut here--
Index: sched-deps.c
===================================================================
--- sched-deps.c (revision 150503)
+++ sched-deps.c (working copy)
@@ -1898,7 +1898,12 @@
sched_analyze_reg (deps, FIRST_STACK_REG, mode, code, insn);
sched_analyze_reg (deps, FIRST_STACK_REG, mode, USE, insn);
}
+
+#ifdef FIRST_MMX_REG
+ if (regno >= FIRST_MMX_REG && regno <= LAST_MMX_REG)
+ sched_analyze_reg (deps, FIRST_STACK_REG, VOIDmode, CLOBBER, insn);
#endif
+#endif
}
else if (MEM_P (dest))
{
@@ -2044,7 +2049,12 @@
sched_analyze_reg (deps, FIRST_STACK_REG, mode, USE, insn);
sched_analyze_reg (deps, FIRST_STACK_REG, mode, SET, insn);
}
+
+#ifdef FIRST_MMX_REG
+ if (regno >= FIRST_MMX_REG && regno <= LAST_MMX_REG)
+ sched_analyze_reg (deps, FIRST_STACK_REG, VOIDmode, CLOBBER, insn);
#endif
+#endif
if (cslr_p && sched_deps_info->finish_rhs)
sched_deps_info->finish_rhs ();
--cut here--
Otherwise, you can just add "asm volatile ("")" as a scheduling barrier.
--
ubizjak at gmail dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Last reconfirmed|0000-00-00 00:00:00 |2009-08-06 10:47:08
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40983
