[Bug tree-optimization/105198] [9/10 Regression] Wrong code for C loop (GCC 12 -O2, GCC 11 -O3)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105198 --- Comment #12 from CVS Commits --- The releases/gcc-10 branch has been updated by Richard Biener : https://gcc.gnu.org/g:29e8fe04e707910b1bcf15cbc2b582ee0e0e93d6 commit r10-10595-g29e8fe04e707910b1bcf15cbc2b582ee0e0e93d6 Author: Richard Biener Date: Fri Apr 8 13:13:29 2022 +0200 tree-optimization/105198 - wrong code with predictive commoning When predictive commoning looks for a looparound PHI it tries to match the entry value definition (a load) up with the appropriate member of the chain. But it fails to consider stmts clobbering the very same memory location inbetween the load and loop entry. In theory we could be more clever on must aliases that would be also picked up from a load (so not exactly stmt_kills_ref_p) and use the stored value from that if it is an exact match. But we currently have no way to propagate this information inside predcom. 2022-04-08 Richard Biener PR tree-optimization/105198 * tree-predcom.c (find_looparound_phi): Check whether the found memory location of the entry value is clobbered inbetween the value we want to use and loop entry. * gcc.dg/torture/pr105198.c: New testcase. (cherry picked from commit e5453bcc217ea4ac53a4ac277661d6ef0ccd425b)
[Bug tree-optimization/105198] [9/10 Regression] Wrong code for C loop (GCC 12 -O2, GCC 11 -O3)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105198 --- Comment #11 from Tomas Kalibera --- Thanks for the very quick fix! I confirm that when R is built with the fixed version of GCC 12, the R testcase for MASS is fixed, it works with -O2.
[Bug tree-optimization/105198] [9/10 Regression] Wrong code for C loop (GCC 12 -O2, GCC 11 -O3)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105198 Richard Biener changed: What|Removed |Added Summary|[9/10/11 Regression] Wrong |[9/10 Regression] Wrong |code for C loop (GCC 12 |code for C loop (GCC 12 |-O2, GCC 11 -O3)|-O2, GCC 11 -O3) Known to fail||11.2.0 Known to work||11.2.1, 12.0 --- Comment #10 from Richard Biener --- Fixed where the testcase fails, I'll eventually backport further for the latent issue.
