[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Comment #23 from ubizjak at gmail dot com 2008-03-19 10:38 --- As stated in comment #16 and #17, the LCM infrastructure doesn't support mode switching in the way that would be usable for emms. Additionally, there are MANY problems expected when sharing x87 and MMX registers (i.e. handling of uninitialized x87 registers at the beginning of the function - this is the reason we don't implement x87 register passing ABI). Automatic MMX vectorization is not exactly a much usable feature nowadays (we have SSE that works quite well here). Due to recent changes in MMX register allocation area, excellent code is produced using MMX intrinsics, I'm closing this bug as WONTFIX. -- ubizjak at gmail dot com changed: What|Removed |Added Status|NEW |RESOLVED Resolution||WONTFIX http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Comment #22 from Richard dot Barnes at stratus dot com 2008-01-04 20:05 --- I have seen this bug in the vector-2 testcases shipped in gcc/gcc/testsuite/gcc.dg/compat when compiling for i386 with -msse2. In vector-2_y.c and vector-2_x.c we end up using both mmx and x87 registers in the same function without any intervening EMMS instruction. This fails in 4.1.2, 3.4.6, and 3.3.1. -- Richard dot Barnes at stratus dot com changed: What|Removed |Added CC||Richard dot Barnes at ||stratus dot com http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Comment #21 from rth at gcc dot gnu dot org 2005-11-02 06:39 --- I'm no longer actively working on this. -- rth at gcc dot gnu dot org changed: What|Removed |Added AssignedTo|rth at gcc dot gnu dot org |unassigned at gcc dot gnu ||dot org Status|ASSIGNED|NEW http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Additional Comments From pluto at agmk dot net 2005-09-22 13:10 ---
Uros,
The mode switching patch ICEs current mainline on ix86.
gcc fbmmx.i -msse -O0,-O1 fails with different insn-errors.
[ -msse -O0 ]
fbmmx.c: In function
#8216;_cairo_pixman_composite_src_add_8000x8000mmx#8217;:
fbmmx.c:2169: error: unable to find a register to spill in class
#8216;MMX_REGS#8217;
fbmmx.c:2169: error: this is the insn:
(insn 174 172 175 7 (set (reg:V8QI 59 [ D.8903 ])
(mem/c/i:V8QI (plus:SI (reg/f:SI 20 frame)
(const_int -16 [0xfff0])) [0 __m2+0 S8 A32])) 776
{*movv8qi_internal} (nil)
(nil))
fbmmx.c:2169: internal compiler error: in spill_failure, at reload1.c:1890
[ -msse -O1 ]
fbmmx.c: In function
#8216;_cairo_pixman_composite_src_add_8000x8000mmx#8217;:
fbmmx.c:2169: error: unable to find a register to spill in class
#8216;MMX_REGS#8217;
fbmmx.c:2169: error: this is the insn:
(insn 166 165 169 9 (set (reg:V8QI 167)
(us_plus:V8QI (mem:V8QI (reg/v/f:SI 4 si [orig:120 src ] [120]) [0 S8
A64])
(mem:V8QI (reg/v/f:SI 2 cx [orig:122 dst ] [122]) [0 S8 A64])))
812 {mmx_usaddv8qi3} (nil)
(nil))
fbmmx.c:2169: internal compiler error: in spill_failure, at reload1.c:1890
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Additional Comments From uros at kss-loka dot si 2005-08-24 14:33
---
There is another bug in ix86_mode_needed() that causes timeouts for
pr20314-1.c. The problem is in asm operands parsing code that gets into
infinite loop. The correct code should increase variable c instead of cc when
comma is found:
config/i386/i386.c (ix86_mode_needed):
...
for (i = 0; i noperands; i++)
{
const char *c = constraints[i];
enum reg_class class;
if (c[0] == '%')
c++;
if (ISDIGIT ((unsigned char) c[0]) c[1] == '\0')
c = constraints[c[0] - '0'];
while (*c)
{
char cc = *c;
int len;
switch (cc)
{
case ',':
c++; here!!
continue;
case '=':
case '+':
case '*':
case '%':
case '!':
case '#':
case '':
case '?':
break;
...
Regarding emms/efpu instructions in loop: I have made some experiments by
inserting mode switching insn before NOTE_INSN_LOOP_BEGIN. The failure in
20050604-1.c is fixed if this mode is set to FPU_MODE_MMX.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Additional Comments From rth at gcc dot gnu dot org 2005-08-23 20:48
---
So, I fixed another case in which we could die in create_pre_exit having
to do with complex return values. But past that, there are failures that
are completely within optimize_mode_switching, e.g. execute/20050604-1.c.
$ ./cc1 -m32 -march=pentium4 z.c
foo
z.c: In function foo:
z.c:28: error: unable to find a register to spill in class MMX_REGS
z.c:28: error: this is the insn:
(insn 14 63 15 2 (set (reg:V4HI 61 [ D.1620 ])
(mem/s/j:V4HI (symbol_ref:SI (u) var_decl 0x2daff160 u)
[0 u.v+0 S8 A64])) 994 {*movv4hi_internal} (nil)
(nil))
The problem is that we have a CFG like
+--+
v |
1-2-3-4
and we place the efpu insn in block 2, but the emms insn in block 4.
Aside from being Less Than Ideal, this results in BOTH mmx and fpu
registers live around the loop, which means we can't allocate anything.
Uros, you should bootstrap i386 with --with-arch=foo, where foo is
whatever machine you have that supports at least mmx. Otherwise, you're
not actually testing this new code on i386 except for the few test
cases that force an -march or -mmx option.
I'll keep looking at it for a bit to see if its something simple, but
we're not going to overhaul optimize_mode_switching for 4.1 if it's
something complicated.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Additional Comments From rth at gcc dot gnu dot org 2005-08-23 21:30 --- Actually, I lied about the CFG. It's actually 1-3 with 2-3 still forming the loop. So LCM did the right thing, technically: for the case in which the loop trip count is zero, we avoid the efpu insn. The problem is, the model we have wrt efpu/emms requires that they be used in balanced pairs. And, really, we'd prefer that these insns be pushed out of loops when possible. But I'm not sure how to address this at the moment. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Additional Comments From rth at gcc dot gnu dot org 2005-08-22 20:32 --- Doing the code review. I've got a local patch for the create_pre_exit ice. I'm going to work to see this in 4.1. -- What|Removed |Added AssignedTo|unassigned at gcc dot gnu |rth at gcc dot gnu dot org |dot org | Status|NEW |ASSIGNED Last reconfirmed|2005-04-27 00:44:45 |2005-08-22 20:32:55 date|| http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Additional Comments From uros at kss-loka dot si 2005-08-19 10:19 --- (In reply to comment #13) current mainline bootstrap still fails. ../../gcc/unwind.inc: In function '_Unwind_ForcedUnwind': ../../gcc/unwind.inc:215: internal compiler error: in create_pre_exit, at mode-switching.c:352 The patch at http://gcc.gnu.org/ml/gcc-patches/2005-08/msg01142.html fixes this problem. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Additional Comments From pluto at agmk dot net 2005-07-23 15:42 --- (In reply to comment #10) (In reply to comment #6) with this patch I get an ice on amd64 bootstrap: In file included from ../../gcc/unwind-dw2.c:256: ../../gcc/config/i386/linux-unwind.h: In function 'x86_64_fallback_frame_state': ../../gcc/config/i386/linux-unwind.h:55: warning: dereferencing type-punned pointer will break strict-aliasing rules ../../gcc/unwind.inc: In function '_Unwind_ForcedUnwind': ../../gcc/unwind.inc:215: internal compiler error: in create_pre_exit, at mode-switching.c:350 Pawel, could you check the patch at http://gcc.gnu.org/ml/gcc-patches/2005- 07/msg01128.html if it fixes bootstrap problems on AMD64? Patch works for me with BOOT_CFLAGS=-02 -msse2 on pentium4, and this is as far as I can test... I check this right now :) I was busy with PR22584 earlier :| -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Additional Comments From pluto at agmk dot net 2005-07-23 17:07 --- current mainline bootstrap still fails. (...) ./xgcc -B./ -B/usr/x86_64-pld-linux/bin/ -isystem /usr/x86_64-pld-linux/include -isystem /usr/x86_64-pld-linux/sys-include -L/home/users/pluto/rpm/BUILD/gcc-4.1-20050723T1611UTC/obj-x86_64-pld-linux/gcc/../ld -O2 -DIN_GCC-W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition -isystem ./include -fPIC -DHAVE_GTHR_DEFAULT -DIN_LIBGCC2 -D__GCC_FLOAT_NOT_NEEDED -I. -I. -I../../gcc -I../../gcc/. -I../../gcc/../include -I../../gcc/../libcpp/include -fvisibility=hidden -DHIDE_EXPORTS -fexceptions -c ../../gcc/unwind-dw2.c -o libgcc/./unwind-dw2.o ../../gcc/unwind.inc: In function '_Unwind_ForcedUnwind': ../../gcc/unwind.inc:215: internal compiler error: in create_pre_exit, at mode-switching.c:352 (...) make[3]: *** [libgcc/./unwind-dw2.o] Error 1 make[3]: Leaving directory `/home/users/pluto/rpm/BUILD/gcc-4.1-20050723T1611UTC/obj-x86_64-pld-linux/gcc' make[2]: *** [stmp-multilib] Error 2 make[2]: Leaving directory `/home/users/pluto/rpm/BUILD/gcc-4.1-20050723T1611UTC/obj-x86_64-pld-linux/gcc' make[1]: *** [stage1_build] Error 2 make[1]: Leaving directory `/home/users/pluto/rpm/BUILD/gcc-4.1-20050723T1611UTC/obj-x86_64-pld-linux/gcc' make: *** [bootstrap] Error 2 -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Additional Comments From uros at kss-loka dot si 2005-07-22 09:33 --- Whee, it looks that x86_64 breakage has gone. I have succesfully compiled unwind-dw2.c with patched x86_64 crosscompiler. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Additional Comments From uros at kss-loka dot si 2005-07-21 08:46 --- (In reply to comment #6) with this patch I get an ice on amd64 bootstrap: In file included from ../../gcc/unwind-dw2.c:256: ../../gcc/config/i386/linux-unwind.h: In function 'x86_64_fallback_frame_state': ../../gcc/config/i386/linux-unwind.h:55: warning: dereferencing type-punned pointer will break strict-aliasing rules ../../gcc/unwind.inc: In function '_Unwind_ForcedUnwind': ../../gcc/unwind.inc:215: internal compiler error: in create_pre_exit, at mode-switching.c:350 Pawel, could you check the patch at http://gcc.gnu.org/ml/gcc-patches/2005- 07/msg01128.html if it fixes bootstrap problems on AMD64? Patch works for me with BOOT_CFLAGS=-02 -msse2 on pentium4, and this is as far as I can test... -- What|Removed |Added URL||http://gcc.gnu.org/ml/gcc- ||patches/2005- ||07/msg01128.html Keywords||patch http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Additional Comments From pluto at agmk dot net 2005-06-25 06:26 --- (In reply to comment #7) (in reply to comment #6) This is a known problem, with a hack to mode-switching.c at http://gcc.gnu.org/ml/gcc-patches/2005-06/msg01434.html. Please, could you try to apply the mode-switching.c part of the patch and see if it fix an ice for you. with this hack bootstrap still ices. ../../gcc/unwind.inc: In function '_Unwind_ForcedUnwind': ../../gcc/unwind.inc:215: internal compiler error: in create_pre_exit, at mode-switching.c:362 -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Additional Comments From uros at kss-loka dot si 2005-06-25 07:40 --- (In reply to comment #8) This is a known problem, with a hack to mode-switching.c at http://gcc.gnu.org/ml/gcc-patches/2005-06/msg01434.html. Please, could you try to apply the mode-switching.c part of the patch and see if it fix an ice for you. with this hack bootstrap still ices. ../../gcc/unwind.inc: In function '_Unwind_ForcedUnwind': ../../gcc/unwind.inc:215: internal compiler error: in create_pre_exit, at mode-switching.c:362 It was a hack anyway :---( Thanks for the report, I'll try to find a proper fix in the next week. (BTW: It fails for x86-64, because this target enables mmx by default.) -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Additional Comments From pluto at agmk dot net 2005-06-24 14:03 --- (In reply to comment #5) Uros, also for you it seems... (http://gcc.gnu.org/ml/gcc-patches/2005-06/msg01724.html) with this patch I get an ice on amd64 bootstrap: (..) -c ../../gcc/unwind-dw2.c -o libgcc/./unwind-dw2.o In file included from ../../gcc/unwind-dw2.c:256: ../../gcc/config/i386/linux-unwind.h: In function 'x86_64_fallback_frame_state': ../../gcc/config/i386/linux-unwind.h:55: warning: dereferencing type-punned pointer will break strict-aliasing rules ../../gcc/unwind.inc: In function '_Unwind_ForcedUnwind': ../../gcc/unwind.inc:215: internal compiler error: in create_pre_exit, at mode-switching.c:350 -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Additional Comments From uros at kss-loka dot si 2005-06-24 20:33 --- (in reply to comment #6) ../../gcc/unwind.inc: In function '_Unwind_ForcedUnwind': ../../gcc/unwind.inc:215: internal compiler error: in create_pre_exit, at mode-switching.c:350 This is a known problem, with a hack to mode-switching.c at http://gcc.gnu.org/ml/gcc-patches/2005-06/msg01434.html. As this will fix an ice you got, the real problem is in fact, that this function is (like __builtin_apply case) trying to handle returned %mm register together with %st and this will confuse mode switching in the exit block. Please, could you try to apply the mode-switching.c part of the patch and see if it fix an ice for you. However, I think that __builtin_apply should process only an x87 output register, and should be limited only to functions that return in FPU_X87 mode. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Additional Comments From steven at gcc dot gnu dot org 2005-06-21 11:20 --- Uros, also for you it seems... (http://gcc.gnu.org/ml/gcc-patches/2005-06/msg01724.html) -- What|Removed |Added CC||uros at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Additional Comments From rth at gcc dot gnu dot org 2005-01-18 09:52 --- *** Bug 17415 has been marked as a duplicate of this bug. *** -- What|Removed |Added CC||plm at pcug dot org dot au http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Additional Comments From pinskia at gcc dot gnu dot org 2004-12-26 21:20 --- Confirmed, there is a dup of this filed already. -- What|Removed |Added Status|UNCONFIRMED |NEW Ever Confirmed||1 Keywords||wrong-code Last reconfirmed|-00-00 00:00:00 |2004-12-26 21:20:02 date|| http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Additional Comments From pinskia at gcc dot gnu dot org 2004-12-27 00:24 --- *** Bug 14801 has been marked as a duplicate of this bug. *** -- What|Removed |Added CC||belyshev at depni dot sinp ||dot msu dot ru http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
[Bug target/19161] No emms or femms emitted between MMX and FP instructions
--- Additional Comments From pinskia at gcc dot gnu dot org 2004-12-27 00:26 --- Found the bug finnally, see PR 14801 for an example. Also PR 16872 is another example. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19161
