Created attachment 49758 [details] reduced testcase Compiler output: $ x86_64-pc-linux-gnu-gcc -O -fno-tree-forwprop testcase.c during GIMPLE pass: switchlower testcase.c: In function 'foo': testcase.c:4:1: internal compiler error: in decompose, at wide-int.h:984 4 | foo (unsigned char uc) | ^~~ 0x61a4c0 wi::int_traits<generic_wide_int<wide_int_ref_storage<false, false> > >::decompose(long*, unsigned int, generic_wide_int<wide_int_ref_storage<false, false> > const&) /repo/gcc-trunk/gcc/wide-int.h:984 0xac2400 wi::int_traits<generic_wide_int<wide_int_storage> >::decompose(long*, unsigned int, generic_wide_int<wide_int_storage> const&) /repo/gcc-trunk/gcc/wide-int.h:1933 0xac2400 wide_int_ref_storage<true, false>::wide_int_ref_storage<generic_wide_int<wide_int_storage> >(generic_wide_int<wide_int_storage> const&, unsigned int) /repo/gcc-trunk/gcc/wide-int.h:1034 0xac2400 generic_wide_int<wide_int_ref_storage<true, false> >::generic_wide_int<generic_wide_int<wide_int_storage> >(generic_wide_int<wide_int_storage> const&, unsigned int) /repo/gcc-trunk/gcc/wide-int.h:790 0xac2400 bool wi::ltu_p<generic_wide_int<wide_int_storage>, generic_wide_int<wide_int_storage> >(generic_wide_int<wide_int_storage> const&, generic_wide_int<wide_int_storage> const&) /repo/gcc-trunk/gcc/wide-int.h:1937 0x10aa543 bool wi::lt_p<generic_wide_int<wide_int_storage>, generic_wide_int<wide_int_storage> >(generic_wide_int<wide_int_storage> const&, generic_wide_int<wide_int_storage> const&, signop) /repo/gcc-trunk/gcc/wide-int.h:1963 0x10aa543 tree_switch_conversion::bit_test_cluster::emit(tree_node*, tree_node*, tree_node*, basic_block_def*) /repo/gcc-trunk/gcc/tree-switch-conversion.c:1562 0x10aac3b tree_switch_conversion::switch_decision_tree::try_switch_expansion(vec<tree_switch_conversion::cluster*, va_heap, vl_ptr>&) /repo/gcc-trunk/gcc/tree-switch-conversion.c:1893 0x10ab413 tree_switch_conversion::switch_decision_tree::analyze_switch_statement() /repo/gcc-trunk/gcc/tree-switch-conversion.c:1823 0x10ac217 execute /repo/gcc-trunk/gcc/tree-switch-conversion.c:2570 Please submit a full bug report, with preprocessed source if appropriate. Please include the complete backtrace with any bug report. See <https://gcc.gnu.org/bugs/> for instructions. $ 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-r11-5984-20201214092247-gcf7efe2d36f-checking-yes-rtl-df-extra-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/11.0.0/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 --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-r11-5984-20201214092247-gcf7efe2d36f-checking-yes-rtl-df-extra-amd64 Thread model: posix Supported LTO compression algorithms: zlib zstd gcc version 11.0.0 20201214 (experimental) (GCC)
I can fix it.
Created attachment 49762 [details] Tentative fix
The master branch has been updated by Eric Botcazou <ebotcazou@gcc.gnu.org>: https://gcc.gnu.org/g:61e3c180ad6913fa5af39059de5ba7b3bde50cda commit r11-6110-g61e3c180ad6913fa5af39059de5ba7b3bde50cda Author: Eric Botcazou <ebotcazou@adacore.com> Date: Wed Dec 16 09:39:07 2020 +0100 Fix PR tree-optimization/98272 This fixes the precision mismatch introduced by the previous change. gcc/ChangeLog: PR tree-optimization/98272 * tree-switch-conversion.c (bit_test_cluster::emit): When finding out whether the entry test can be merged in the bit test, do the computation using the type of the index expression. gcc/testsuite/ChangeLog: * gcc.dg/pr98272.c: New test.
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