https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78312
Bug ID: 78312
Summary: [7 Regression] wrong code probably due to VRP of
multiplication
Product: gcc
Version: 7.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: zsojka at seznam dot cz
Target Milestone: ---
Target: x86_64-pc-linux-gnu
Created attachment 40022
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40022&action=edit
reduced testcase
Output:
$ x86_64-pc-linux-gnu-gcc testcase.c -O2
$ ./a.out
Aborted
$ 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-242046-checking-yes-rtl-df-extra-nographite-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/7.0.0/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
--without-cloog --without-ppl --without-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-242046-checking-yes-rtl-df-extra-nographite-amd64
Thread model: posix
gcc version 7.0.0 20161110 (experimental) (GCC)
The .vrp1 dump shows:
...
# RANGE ~[1, 65534]
_6 = _2 * _5;
# RANGE [0, 1] NONZERO 1
_7 = _6 * _6;
...
I believe that the code has defined behavior due to the (unsigned) cast.
