[Bug tree-optimization/126658] [16/17 Regression] Wrong code at -O1 on x86_64-pc-linux-gnu
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126658 --- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Richard Biener <[email protected]>: https://gcc.gnu.org/g:b947bd4aac67ba3bdb6030aa4ac2f3eb0204df05 commit r17-3179-gb947bd4aac67ba3bdb6030aa4ac2f3eb0204df05 Author: Richard Biener <[email protected]> Date: Thu Aug 6 11:49:20 2026 +0200 tree-optimization/126658 - TARGET_MEM_REF and non-null infering The following adjusts three places to avoid infering that operand zero of a TARGET_MEM_REF is literally dereferenced and thus may not be NULL. This reflects the fact that within IVOPTs we cannot easily guarantee that there'll be a real pointer in TMR_BASE and fiddling with IVOPTs proved fragile. So we are taking a conservative stance here, with carving out the likely common case of a scaled index which is unlikely going to be a pointer (fingers crossing). For the testcase at hand the apparent non-NULLness was triggering a jump-threading miscompiling the testcase. PR tree-optimization/126658 * gimple.cc (check_loadstore): Restrict TARGET_MEM_REF handling. * gimple-ssa-isolate-paths.cc (check_loadstore): Likewise. * gimple-range-infer.cc (non_null_loadstore): Likewise. * gcc.dg/torture/pr126658.c: New testcase.