https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85508
Bug ID: 85508 Summary: runtime error in config/i386/i386.c Product: gcc Version: 8.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: dcb314 at hotmail dot com Target Milestone: --- For this C code: typedef char a; typedef b; c; d(e) { for (;; f()) { a *g; b h; for (h = 0; h < 27; h++) for (e = 0; e <= 26; ++e) *g &= c; } } compiled by a ubsan version of recent gcc trunk, I get this: $ ~/gcc/results/bin/gcc -c -O3 -w bug431.c ../../trunk/gcc/config/i386/i386.c:43197:33: runtime error: left shift of negative value -1 $ ~/gcc/results/bin/gcc -v Using built-in specs. COLLECT_GCC=/home/dcb/gcc/results/bin/gcc COLLECT_LTO_WRAPPER=/home/dcb/gcc/results.259553.ubsan/libexec/gcc/x86_64-pc-linux-gnu/8.0.1/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: ../trunk/configure --prefix=/home/dcb/gcc/results.259553.ubsan --with-build-config=bootstrap-ubsan --disable-multilib --disable-werror --enable-checking=df,extra,fold,rtl,yes --enable-languages=c,c++,fortran Thread model: posix gcc version 8.0.1 20180422 (experimental) (GCC) $ File ../../trunk/gcc/config/i386/i386.c line 43197 is x = gen_int_mode (INTVAL (x) << 8, HImode);