Merge remote-tracking branch 'origin/master' into unswitch

Bootstraps OK, has

FAIL: gfortran.fortran-torture/execute/forall_7.f90 execution,  -O3 -g

and ICEs 511.povray_r, 526.blender_r, 538.imagick_r with -Ofast znver2

splines.cpp:687:5: internal compiler error: in tree_unswitch_single_loop, at tree-ssa-loop-unswitch.cc:902

blender/source/blender/modifiers/intern/MOD_weightvg_util.c:120:6: internal compiler error: Segmentation fault

magick/composite.c:1631:32: internal compiler error: in tree_unswitch_single_loop, at tree-ssa-loop-unswitch.cc:902

the 902 is the size estimation assert recently added.

diff --cc gcc/doc/invoke.texi
Simple merge

diff --cc gcc/tree-cfg.cc
Simple merge