https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61520
Bug ID: 61520
Summary: False warning: array subscript is below array bounds
(-Warray-bounds -O -ftree-vrp -funroll-loops)
Product: gcc
Version: 4.8.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: svojtovich at gmail dot com
gcc emits false warning for the following code:
gcc -Warray-bounds -O -ftree-vrp -funroll-loops -c dec.c -o dec.o
or gcc -Warray-bounds -O3 -c dec.c -o dec.o
static const int powers10[2 + 1]= { 1, 10, 100 };
int remove_leading_zeroes(int decimals, int var)
{
decimals%= 2;
while (var < powers10[decimals--]) /* no-op */;
return decimals;
}
This is simplified code, original code is available here:
http://bazaar.launchpad.net/~maria-captains/maria/10.0/view/head:/strings/decimal.c#L251
Note that original code ensures (within the same function) that array subscript
won't underrun array bounds.
4.8.2 seem to be also affected, look for compile results for decimal.c:
https://buildbot.askmonty.org/buildbot/builders/kvm-deb-trusty-amd64/builds/261/steps/compile/logs/stdio
