https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97312
--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:781634daea8cb788efb33994f4a19df76598542e commit r11-3744-g781634daea8cb788efb33994f4a19df76598542e Author: Jakub Jelinek <ja...@redhat.com> Date: Fri Oct 9 10:19:16 2020 +0200 vrp: Fix up gcc.target/aarch64/pr90838.c [PR97312, PR94801] > Perhaps another way out of this would be document and enforce that > __builtin_c[lt]z{,l,ll} etc calls are undefined at zero, but C[TL]Z ifn > calls are defined there based on *_DEFINED_VALUE_AT_ZERO (*) == 2 The following patch implements that, i.e. __builtin_c?z* now take full advantage of them being UB at zero, while the ifns are well defined at zero if *_DEFINED_VALUE_AT_ZERO (*) == 2. That is what fixes PR94801. Furthermore, to fix PR97312, if it is well defined at zero and the value at zero is prec, we don't lower the maximum unless the argument is known to be non-zero. For gimple-range.cc I guess we could improve it if needed e.g. by returning a [0,7][32,32] range for .CTZ of e.g. [0,137], but for now it (roughly) matches what vr-values.c does. 2020-10-09 Jakub Jelinek <ja...@redhat.com> PR tree-optimization/94801 PR target/97312 * vr-values.c (vr_values::extract_range_basic) <CASE_CFN_CLZ, CASE_CFN_CTZ>: When stmt is not an internal-fn call or C?Z_DEFINED_VALUE_AT_ZERO is not 2, assume argument is not zero and thus use [0, prec-1] range unless it can be further improved. For CTZ, don't update maxi from upper bound if it was previously prec. * gimple-range.cc (gimple_ranger::range_of_builtin_call) <CASE_CFN_CLZ, CASE_CFN_CTZ>: Likewise. * gcc.dg/tree-ssa/pr94801.c: New test.
