https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93385
Bug ID: 93385
Summary: [10 Regression] wrong code with u128 modulo at -O2
-fno-dce -fno-ipa-cp -fno-tree-dce
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: zsojka at seznam dot cz
Target Milestone: ---
Host: x86_64-pc-linux-gnu
Created attachment 47693
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=47693&action=edit
reduced testcase
Output:
$ x86_64-pc-linux-gnu-gcc -O2 -fno-dce -fno-ipa-cp -fno-tree-dce testcase.c
$ ./a.out
Floating point exception
(gdb) bt
#0 0x00000000004011c4 in __udivmodti4 (rp=<synthetic pointer>, d=0, n=0) at
/repo/gcc-trunk/libgcc/libgcc2.c:1046
#1 __umodti3 (u=<optimized out>, v=<optimized out>) at
/repo/gcc-trunk/libgcc/libgcc2.c:1310
#2 0x0000000000401056 in c (d=<optimized out>) at testcase.c:7
#3 main () at testcase.c:16
The code seems to compute 0 % 0 (all rsi:rdi rcx:rdx are == 0)
$ x86_64-pc-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest-amd64/bin/x86_64-pc-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-20200122013655-10502831581-checking-yes-rtl-df-extra-nobootstrap-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/10.0.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-valgrind-annotations --disable-nls --enable-checking=yes,rtl,df,extra
--disable-bootstrap --with-cloog --with-ppl --with-isl
--build=x86_64-pc-linux-gnu --host=x86_64-pc-linux-gnu
--target=x86_64-pc-linux-gnu --with-ld=/usr/bin/x86_64-pc-linux-gnu-ld
--with-as=/usr/bin/x86_64-pc-linux-gnu-as --disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-20200122013655-10502831581-checking-yes-rtl-df-extra-nobootstrap-amd64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 10.0.1 20200122 (experimental) (GCC)
