[Bug tree-optimization/69376] [6 Regression] wrong code at -Os and above on x86_64-linux-gnu

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69376

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Created attachment 37433
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37433&action=edit
patch

Patch that I have tested but which exposes another latent issue?

FAIL: 21_strings/basic_string/requirements/exception/generation_prohibited.cc
ex
ecution test
FAIL: ext/vstring/requirements/exception/generation_prohibited.cc execution
test


on x86_64 both -m32 and -m64 with allocating gigabytes of memory and eventually
throwing bad_alloc ().  -fno-tree-pre recovers from this, so does -fno-tree-vrp
(as expected), so does disabling only vrp2 (or vrp1).