https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65027
Bug ID: 65027
Summary: failure to emit diagnostic when optimizing using
undefined behaviour
Product: gcc
Version: 5.0
Status: UNCONFIRMED
Keywords: diagnostic
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: rearnsha at gcc dot gnu.org
Target: x86_64, arm
The following code fragment, when compiled at -O3 is quite reasonably optimized
to return 33 (since any other return value relies on first encountering
undefined behaviour). However, the -Waggressive-loop-optimizations diagnostic
option fails to cause a warning about this to be reported.
int x[5];
int foo()
{
int i;
for (i = 0; i < 30; i++)
if (x[i] == 0)
return 33;
return 1;
}
This code should trigger do_warn_aggressive_loop_optimizations to emit a
diagnostic.
It probably doesn't at present because the loop is removed entirely.
