[Bug tree-optimization/58143] [4.8/4.9 regression] wrong code at -O3

[bernd.edlinger at hotmail dot de]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58143

Bernd Edlinger <bernd.edlinger at hotmail dot de> changed:

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--- Comment #14 from Bernd Edlinger <bernd.edlinger at hotmail dot de> ---
Created attachment 30699
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30699&action=edit
patch to prevent undefined execution in lim

OK, this time only the lim pass should be the prevented from
introducing undefined behavior that was not there originally.

This triggered a minor regression in gcc.target/i386/pr53397-1.c;
Here lim used to move the expression "2*step" out of the loop,
but this may cause undefined behavior on case of overflow,
I propose to resolve this by adding -fno-strict-overflow,
The test case looks pretty constructed anyway.