https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116420
--- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jeff Law <l...@gcc.gnu.org>: https://gcc.gnu.org/g:c9377734b798d8d311dfd3a5618dc49407703b93 commit r15-3095-gc9377734b798d8d311dfd3a5618dc49407703b93 Author: Jeff Law <j...@ventanamicro.com> Date: Thu Aug 22 12:48:49 2024 -0600 [PR rtl-optimization/116420] Fix interesting block bitmap DF dataflow The DF framework provides us a way to run dataflow problems on sub-graphs. Naturally a bitmap of interesting blocks is passed into those routines. At a confluence point, the DF framework will not mark a block for re-processing if it's not in that set of interesting blocks. When ext-dce sets up that set of interesting blocks it's using the wrong counter. ie, it's using n_basic_blocks rather than last_basic_block. If there are holes in the block indices, some number of blocks won't get marked as interesting. In this case the block needing reprocessing has an index higher than n_basic_blocks. It never gets reprocessed and the newly found live chunks don't propagate further up the CFG -- ultimately resulting in a pseudo appearing to have only the low 8 bits live, when in fact the low 32 bits are actually live. Fixed in the obvious way, by using last_basic_block instead. Bootstrapped and regression tested on x86_64. Pushing to the trunk. PR rtl-optimization/116420 gcc/ * ext-dce.cc (ext_dce_init): Fix loop iteration when setting up the interesting block for DF to analyze. gcc/testsuite * gcc.dg/torture/pr116420.c: New test.
