(Please CC me in the replies, I am not subscribed to the list)
Hi,
I am currently trying to switch the SH backend to use the LRA register allocater
by default with the help of patches by Oleg and Kaz (CC'ed) to address various
issues when using LRA by default. The patches can all be found in the
corresponding
Bugzilla report [1].
Currently, I have applied the following patches from the bug report:
- 58832
- 58833
- 58883
- 58905
plus the following change to enable LRA by default:
diff --git a/gcc/config/sh/sh.opt b/gcc/config/sh/sh.opt
index c44cfe70cb1..718dfb744ff 100644
--- a/gcc/config/sh/sh.opt
+++ b/gcc/config/sh/sh.opt
@@ -299,5 +299,5 @@ Target Var(TARGET_FSRRA)
Enable the use of the fsrra instruction.
mlra
-Target Var(sh_lra_flag) Init(0) Save
+Target Var(sh_lra_flag) Init(1) Save
Use LRA instead of reload (transitional).
With these changes applied, I have configured and built GCC from Git as follows:
# ../configure --disable-multilib --enable-multiarch --enable-bootstrap
--enable-languages=c,c++
# make -j32
which fails on QEMU with a segmentation fault:
/srv/glaubitz/gcc/build/./gcc/xgcc -B/srv/glaubitz/gcc/build/./gcc/
-B/usr/local/sh4-unknown-linux-gnu/bin/ \
-B/usr/local/sh4-unknown-linux-gnu/lib/ -isystem
/usr/local/sh4-unknown-linux-gnu/include -isystem \
/usr/local/sh4-unknown-linux-gnu/sys-include -fno-checking -g -O2 -O2 -g -O2
-DIN_GCC \
-W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual -Wstrict-prototypes
-Wmissing-prototypes \
-Wold-style-definition -isystem ./include -fpic -DNO_FPSCR_VALUES -w
-Wno-sync-nand -g -DIN_LIBGCC2 \
-fbuilding-libgcc -fno-stack-protector -fpic -DNO_FPSCR_VALUES -w
-Wno-sync-nand -I. -I. \
-I../.././gcc -I../../../libgcc -I../../../libgcc/. -I../../../libgcc/../gcc
-I../../../libgcc/../include \
-DHAVE_CC_TLS -o _paritysi2.o -MT _paritysi2.o -MD -MP -MF _paritysi2.dep
-DL_paritysi2 \
-c ../../../libgcc/libgcc2.c -fvisibility=hidden -DHIDE_EXPORTS
during GIMPLE pass: waccess
../../../libgcc/libgcc2.c: In function '__muldi3':
../../../libgcc/libgcc2.c:538:1: internal compiler error: Segmentation fault
538 | }
| ^
during GIMPLE pass: waccess
This is reproducible on real hardware (Renesas SH-7785LCR, Linux 6.5.0), so
it's not an emulation issue.
I have tried to debug this issue with my Linux-SH-enabled GDB fork [2] and got
the following backtrace:
(gdb) bt
#0 0x0109fee4 in wi::add_large(long long*, long long const*, unsigned int,
long long const*, unsigned int, unsigned int, signop, wi::overflow_type*) ()
#1 0x00bdbc10 in
access_ref::add_offset(generic_wide_int<fixed_wide_int_storage<128> > const&,
generic_wide_int<fixed_wide_int_storage<128> > const&) ()
#2 0x00bdd0e8 in compute_objsize_r(tree_node*, gimple*, bool, int,
access_ref*, ssa_name_limit_t&, pointer_query*) ()
#3 0x00000000 in ?? ()
(gdb) display/i $pc
1: x/i $pc
=> 0x109fee4 <_ZN2wi9add_largeEPxPKxjS2_jj6signopPNS_13overflow_typeE+84>:
mov.l @r2,r3
(gdb) x/wx $r2
0x7c07eaa0: Cannot access memory at address 0x7c07eaa0
(gdb)
I have also tried disabling late combine by SH by default, but that didn't help:
diff --git a/gcc/config/sh/sh.cc b/gcc/config/sh/sh.cc
index 280588268ae..dca27893536 100644
--- a/gcc/config/sh/sh.cc
+++ b/gcc/config/sh/sh.cc
@@ -1047,6 +1047,9 @@ sh_override_options_after_change (void)
str_align_functions = r;
}
}
+
+ if (!OPTION_SET_P (flag_late_combine_instructions))
+ flag_late_combine_instructions = 0;
}
^L
/* Print the operand address in x to the stream. */
Thus, I have now run out of ideas (as I'm not really a compiler expert).
Does anyone else have any other suggestions?
Thanks,
Adrian
PS: Would be great if we could upstream Linux SH native GDB support from [2]
as well, in case any binutils-gdb maintainer is reading here.
> [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55212
> [2] https://github.com/glaubitz/binutils-gdb/tree/linux-sh
--
.''`. John Paul Adrian Glaubitz
: :' : Debian Developer
`. `' Physicist
`- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913
