[Bug target/50341] calls via function pointer wrongly scheduled giving invalid TOC pointer
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50341 Michael Meissner meissner at gcc dot gnu.org changed: What|Removed |Added Status|ASSIGNED|RESOLVED Resolution||FIXED --- Comment #6 from Michael Meissner meissner at gcc dot gnu.org 2011-09-19 17:08:47 UTC --- Patch applied to trunk and GCC 4.6 branches not to split the load of the new TOC and the call. If we want to fix the underlying cause of the HIGH/LO_SUM not being optimized so the split can be re-enabled, reopen the bug.
[Bug target/50341] calls via function pointer wrongly scheduled giving invalid TOC pointer
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50341
Michael Meissner meissner at gcc dot gnu.org changed:
What|Removed |Added
CC||meissner at gcc dot gnu.org
--- Comment #3 from Michael Meissner meissner at gcc dot gnu.org 2011-09-15
18:32:45 UTC ---
From the example in the bug, it is the 3rd cpu_fprintf, where it decides to
move loading up an address into register 27, and move the load of the address
before the call, since register 27 is preserved across calls.
void cpu_dump_state (struct CPUPPCState *env, FILE *f, fprintf_function
cpu_fprintf,
int flags)
{
int i;
cpu_fprintf(f, NIP %016 l xLR %016 l x CTR
%016 l x XER %016 l x \n,
env-nip, env-lr, env-ctr, env-xer);
cpu_fprintf(f, MSR %016 l x HID0 %016 l x HF
%016 l x idx %d\n, env-msr, env-spr[(0x3F0)],
env-hflags, env-mmu_idx);
cpu_fprintf(f, TB %08 u %08 l u
DECR %08 u
\n,
cpu_ppc_load_tbu(env), cpu_ppc_load_tbl(env)
, cpu_ppc_load_decr(env)
);
These are the insns that are moved before the call:
(insn 1105 153 203 2 (set (reg/f:DI 27 27 [603])
(const:DI (plus:DI (reg:DI 2 2)
(high:DI (const:DI (unspec:DI [
(symbol_ref/f:DI (*.LC5) [flags 0x82]
var_decl 0xfff931e6360 *.LC5)
] UNSPEC_TOCREL)) 513 {largetoc_high}
(expr_list:REG_EQUIV (const:DI (plus:DI (reg:DI 2 2)
(high:DI (const:DI (unspec:DI [
(symbol_ref/f:DI (*.LC5) [flags 0x82]
var_decl 0xfff931e6360 *.LC5)
] UNSPEC_TOCREL)
(nil)))
(insn 1107 161 204 2 (set (reg/f:DI 27 27 [601])
(lo_sum:DI (reg/f:DI 27 27 [603])
(const:DI (unspec:DI [
(symbol_ref/f:DI (*.LC5) [flags 0x82] var_decl
0xfff931e6360 *.LC5)
] UNSPEC_TOCREL 514 {largetoc_low}
(expr_list:REG_EQUIV (symbol_ref/f:DI (*.LC5) [flags 0x82] var_decl
0xfff931e6360 *.LC5)
(nil)))
The RTL logic is not looking into the const.
This is triggered by Alan's patch in June:
2011-06-20 Alan Modra amo...@gmail.com
* config/rs6000/rs6000.c (create_TOC_reference): Wrap high part
of toc-relative address in CONST.
(rs6000_delegitimize_address): Recognize changed address.
(rs6000_legitimize_reload_address): Likewise.
(rs6000_emit_move): Don't force these constants to memory.
* config/rs6000/rs6000.md (tls_gd, tls_gd_high): Wrap high part of
toc-relative address in CONST.
(tls_ld, tls_ld_high, tls_got_dtprel, tls_got_dtprel_high): Likewise.
(tls_got_tprel, tls_got_tprel_high, largetoc_high): Likewise.
Now, I anticipate that the patch in 4.7 will be temporary until we are
confident that we have the right solution, but it is better to put a bandaid on
the patch to limit the damage.
[Bug target/50341] calls via function pointer wrongly scheduled giving invalid TOC pointer
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50341 --- Comment #4 from Michael Meissner meissner at gcc dot gnu.org 2011-09-15 18:34:11 UTC --- Created attachment 25295 -- http://gcc.gnu.org/bugzilla/attachment.cgi?id=25295 Patch for GCC 4.6 that disables the split of the load of the new TOC
[Bug target/50341] calls via function pointer wrongly scheduled giving invalid TOC pointer
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50341 --- Comment #5 from Michael Meissner meissner at gcc dot gnu.org 2011-09-15 18:34:44 UTC --- Created attachment 25296 -- http://gcc.gnu.org/bugzilla/attachment.cgi?id=25296 Patch for GCC 4.7 that disables the split of the load of the new TOC
[Bug target/50341] calls via function pointer wrongly scheduled giving invalid TOC pointer
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50341 Alan Modra amodra at gmail dot com changed: What|Removed |Added Status|UNCONFIRMED |ASSIGNED Last reconfirmed||2011-09-09 AssignedTo|unassigned at gcc dot |amodra at gmail dot com |gnu.org | Ever Confirmed|0 |1 --- Comment #1 from Alan Modra amodra at gmail dot com 2011-09-09 13:01:36 UTC --- Created attachment 25233 -- http://gcc.gnu.org/bugzilla/attachment.cgi?id=25233 testcase extracted from qemu compile with -m64 -O2, look before bctrl instructions in resulting assembly.
[Bug target/50341] calls via function pointer wrongly scheduled giving invalid TOC pointer
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50341 --- Comment #2 from Michael Meissner meissner at gcc dot gnu.org 2011-09-09 20:51:23 UTC --- Author: meissner Date: Fri Sep 9 20:51:18 2011 New Revision: 178740 URL: http://gcc.gnu.org/viewcvs?root=gccview=revrev=178740 Log: Branch for bug 50341 Added: branches/ibm/gcc-4_7-pr50341/ - copied from r178641, trunk/
