re PR tree-optimization/53265 (Warn when undefined behavior implies smaller iteration count)
PR tree-optimization/53265
* common.opt (Waggressive-loop-optimizations): New option.
* tree-ssa-loop-niter.c: Include tree-pass.h.
(do_warn_aggressive_loop_optimizations): New function.
(record_estimate): Call it. Don't add !is_exit bounds to loop->bounds
if number_of_latch_executions returned constant.
(estimate_numbers_of_iterations_loop): Call number_of_latch_executions
early. If number_of_latch_executions returned constant, set
nb_iterations_upper_bound back to it.
* cfgloop.h (struct loop): Add warned_aggressive_loop_optimizations
field.
* Makefile.in (tree-ssa-loop-niter.o): Depend on $(TREE_PASS_H).
* doc/invoke.texi (-Wno-aggressive-loop-optimizations): Document.
* gcc.dg/pr53265.c: New test.
* gcc.dg/torture/pr49518.c: Add -Wno-aggressive-loop-optimizations
to dg-options.
* g++.dg/opt/longbranch2.C (EBCOTLut): Double sizes of a2 and a3
arrays.
* gcc.dg/tree-ssa/cunroll-10.c (main): Rename to foo. Add argument
n, use it as high bound instead of 4.
* unwind-dw2.c (execute_cfa_program): Avoid
-Waggressive-array-optimizations warnings for DW_CFA_GNU_window_save
on targets with DWARF_FRAME_REGISTERS < 32.