8f571e6471
As observed by Jakub in comment #2 of PR 98865, the expression -(a>>63) is optimized in GENERIC but not in GIMPLE. Investigating further it turns out that this is one of a few transformations performed by fold_negate_expr in fold-const.c that aren't yet performed by match.pd. This patch moves/duplicates them there, and should be relatively safe as these transformations are already performed by the compiler, but just in different passes. This revised patch adds a Boolean simplify argument to tree-ssa-sccvn.c's vn_nary_build_or_lookup_1 to control whether simplification should be performed before value numbering, updating the callers, but then avoiding simplification when constructing/value-numbering NEGATE_EXPR. This avoids the regression of gcc.dg/tree-ssa/ssa-free-88.c, and enables the new test case(s) to pass. 2021-09-22 Roger Sayle <roger@nextmovesoftware.com> Richard Biener <rguenther@suse.de> gcc/ChangeLog * match.pd (negation simplifications): Implement some negation folding transformations from fold-const.c's fold_negate_expr. * tree-ssa-sccvn.c (vn_nary_build_or_lookup_1): Add a SIMPLIFY argument, to control whether the op should be simplified prior to looking up/assigning a value number. (vn_nary_build_or_lookup): Update call to vn_nary_build_or_lookup_1. (vn_nary_simplify): Likewise. (visit_nary_op): Likewise, but when constructing a NEGATE_EXPR now call vn_nary_build_or_lookup_1 disabling simplification. gcc/testsuite/ChangeLog * gcc.dg/fold-negate-1.c: New test case.
This directory contains the GNU Compiler Collection (GCC). The GNU Compiler Collection is free software. See the files whose names start with COPYING for copying permission. The manuals, and some of the runtime libraries, are under different terms; see the individual source files for details. The directory INSTALL contains copies of the installation information as HTML and plain text. The source of this information is gcc/doc/install.texi. The installation information includes details of what is included in the GCC sources and what files GCC installs. See the file gcc/doc/gcc.texi (together with other files that it includes) for usage and porting information. An online readable version of the manual is in the files gcc/doc/gcc.info*. See http://gcc.gnu.org/bugs/ for how to report bugs usefully. Copyright years on GCC source files may be listed using range notation, e.g., 1987-2012, indicating that every year in the range, inclusive, is a copyrightable year that could otherwise be listed individually.