https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101156
--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-11 branch has been updated by Richard Biener <rgue...@gcc.gnu.org>: https://gcc.gnu.org/g:9e1173009150086a927a6f0e001fd04c5cac54cb commit r11-8698-g9e1173009150086a927a6f0e001fd04c5cac54cb Author: Richard Biener <rguent...@suse.de> Date: Tue Jun 22 12:13:44 2021 +0200 middle-end/101156 - remove not working optimization in gimplification This removes a premature and not working optimization from the gimplifier. When gimplification is requested not to produce a SSA name we try to avoid generating a copy when we did so anyway but instead replace the LHS of its definition. But that only works in case there are no uses of the SSA name already which is something we cannot easily check, so the following removes said optimization. Statistics on the whole bootstrap shows we hit this optimization only for libiberty/cp-demangle.c and overall we have 21652112 gimplifications where just 240 copies are elided. Preserving the optimization would require scanning the original expression and the pre and post sequences for SSA names and uses, that seems excessive to avoid these 240 copies. 2021-06-22 Richard Biener <rguent...@suse.de> PR middle-end/101156 * gimplify.c (gimplify_expr): Remove premature incorrect optimization. * gcc.dg/pr101156.c: New testcase. (cherry picked from commit b4e21c80462682c4e6e5e487fe87107b27f8b4bd)
