https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110313
Bug ID: 110313
Summary: [14 Regression] GCN Fiji reload ICE in
'process_alt_operands'
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Keywords: openmp
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: tschwinge at gcc dot gnu.org
CC: ams at gcc dot gnu.org, burnus at gcc dot gnu.org, jules at
gcc dot gnu.org
Target Milestone: ---
Target: GCN
Between GCC commit
2720bbd597f56742a17119dfe80edc2ba86af255..bc6bd0d608da1609c1caeb04ab795a83720add55
(that is, 2023-05-30 - 2023-06-16) appeared some changes in GCC that cause an
ICE for a small number of libgomp offloading test cases, for GCN offloading
only, and with (default) '-march=fiji' only.
[-PASS:-]{+FAIL: libgomp.c++/../libgomp.c-c++-common/for-9.c (internal
compiler error: Segmentation fault)+}
{+FAIL:+} libgomp.c++/../libgomp.c-c++-common/for-9.c (test for excess
errors)
[-PASS:-]{+UNRESOLVED:+} libgomp.c++/../libgomp.c-c++-common/for-9.c
[-execution test-]{+compilation failed to produce executable+}
[-PASS:-]{+FAIL: libgomp.c/../libgomp.c-c++-common/for-9.c (internal
compiler error: Segmentation fault)+}
{+FAIL:+} libgomp.c/../libgomp.c-c++-common/for-9.c (test for excess
errors)
[-PASS:-]{+UNRESOLVED:+} libgomp.c/../libgomp.c-c++-common/for-9.c
[-execution test-]{+compilation failed to produce executable+}
The latter C++ variant not always observed.
Additionally (same ICE), but so far observed on one system only, when running
the exact same toolchain:
[-PASS:-]{+FAIL: libgomp.c/../libgomp.c-c++-common/for-16.c (internal
compiler error: Segmentation fault)+}
{+FAIL:+} libgomp.c/../libgomp.c-c++-common/for-16.c (test for excess
errors)
[-PASS:-]{+UNRESOLVED:+} libgomp.c/../libgomp.c-c++-common/for-16.c
[-execution test-]{+compilation failed to produce executable+}
The ICE is:
spawn -ignore SIGHUP gcc
../source-gcc/libgomp/testsuite/libgomp.c/../libgomp.c-c++-common/for-9.c
-I../source-gcc/libgomp/testsuite/../../include
-I../source-gcc/libgomp/testsuite/.. -fmessage-length=0
-fno-diagnostics-show-caret -fdiagnostics-color=never -fopenmp -O2 -lm -o
./for-9.exe
during RTL pass: reload
../source-gcc/libgomp/testsuite/libgomp.c/../libgomp.c-c++-common/for-2.h:
In function 'f20_dpf_ds128_runtime':
../source-gcc/libgomp/testsuite/libgomp.c/../libgomp.c-c++-common/for-2.h:346:1:
internal compiler error: Segmentation fault
0xe28adf crash_signal
[...]/source-gcc/gcc/toplev.cc:314
0xc19737 process_alt_operands
[...]/source-gcc/gcc/lra-constraints.cc:2789
0xc19737 curr_insn_transform
[...]/source-gcc/gcc/lra-constraints.cc:4201
0xc1ed0e lra_constraints(bool)
[...]/source-gcc/gcc/lra-constraints.cc:5396
0xbff652 lra(_IO_FILE*)
[...]/source-gcc/gcc/lra.cc:2396
0xb9c639 do_reload
[...]/source-gcc/gcc/ira.cc:5967
0xb9c639 execute
[...]/source-gcc/gcc/ira.cc:6153
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
gcn mkoffload: fatal error: x86_64-pc-linux-gnu-accel-amdgcn-amdhsa-gcc
returned 1 exit status
compilation terminated.
lto-wrapper: fatal error: [...]/amdgcn-amdhsa/mkoffload returned 1 exit
status
'gcc/lra-constraints.cc':
2778 if (operand_reg[nop] != NULL_RTX
2779 /* Output operands and matched input operands are
2780 not inherited. The following conditions do not
2781 exactly describe the previous statement but they
2782 are pretty close. */
2783 && curr_static_id->operand[nop].type != OP_OUT
2784 && (this_alternative_matches < 0
2785 || curr_static_id->operand[nop].type != OP_IN))
2786 {
2787 int last_reload = (lra_reg_info[ORIGINAL_REGNO
2788 (operand_reg[nop])]
2789 .last_reload);
Tobias mentioned that 'operand_reg[nop]' is '(reg/f:DI 16 s16 [3483])'.
It was "obvious" to try, but reverting Vlad's three recent commits:
- commit r14-1891-g154c69039571c66b3a6d16ecfa9e6ff22942f59f "RA: Ignore
conflicts for some pseudos from insns throwing a final exception"
- commit r14-1610-g8cc8707446b77f9413654b31704f5a639673c916 "RA: Constrain
class of pic offset table pseudo to general regs"
- commit r14-1417-g30038a207c10a2783fa2695b62c7c8458ef05e73 "LRA: Update insn
sp offset if its input reload changes SP"
... does *not* cure this issue.
I've not yet tested with a non-offloading, GCN target toolchain (... with
(default) '-march=fiji').
I'm now bisecting.
Once we've located the "offender", I'll see about providing a reproducer -- if
necessary.
