[Bug target/77728] [5/6/7/8 Regression] Miscompilation multiple vector iteration on ARM

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77728

--- Comment #30 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 41259
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41259&action=edit
gcc7-pr77728.patch

This is how I'd have written the aarch32 patch.  It has smaller amount of
changes and calls the sometimes expensive function only if really needed, not
always.  Though, if there are libstdc++ failures, we also need some -Wno-psabi
addition somewhere, perhaps:
--- libstdc++-v3/testsuite/lib/libstdc++.exp 2017-01-16 12:27:56.178985247
+0100
+++ libstdc++-v3/testsuite/lib/libstdc++.exp 2017-04-24 19:58:39.784972214
+0200
@@ -239,7 +239,7 @@ proc libstdc++_init { testfile } {

     # Default settings.
     set cxx [transform "g++"]
-    set cxxflags "-fmessage-length=0"
+    set cxxflags "-fmessage-length=0 -Wno-psabi"
     set cxxpchflags ""
     set cxxvtvflags ""
     set cxxldflags ""