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* [Bug tree-optimization/30318] New: VRP does not create ANIT_RANGEs on overflow
@ 2006-12-28 13:28 rguenth at gcc dot gnu dot org
2006-12-28 19:35 ` [Bug tree-optimization/30318] VRP does not create ANTI_RANGEs " rguenth at gcc dot gnu dot org
2006-12-28 20:33 ` rguenth at gcc dot gnu dot org
0 siblings, 2 replies; 3+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2006-12-28 13:28 UTC (permalink / raw)
To: gcc-bugs
VRP should, if overfow is defined, create anti-ranges if plus or minus
cause wrapping.
void test2 (unsigned int i)
{
if (i <= 0x0fffffffa)
{
return;
}
if (i == 0x0ffffffff)
{
return;
}
{
unsigned int v = i + 2;
{
if (v != 0)
{
if (v != 0x0ffffffff)
{
link_error ();
}
}
}
}
}
we should be able to optimize this. So [UINT_MAX-4, UINT_MAX-1] + 2
is ~[1, UINT_MAX-1].
(I have a patch)
--
Summary: VRP does not create ANIT_RANGEs on overflow
Product: gcc
Version: 4.3.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: enhancement
Priority: P3
Component: tree-optimization
AssignedTo: rguenth at gcc dot gnu dot org
ReportedBy: rguenth at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30318
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2006-12-28 13:28 [Bug tree-optimization/30318] New: VRP does not create ANIT_RANGEs on overflow rguenth at gcc dot gnu dot org
2006-12-28 19:35 ` [Bug tree-optimization/30318] VRP does not create ANTI_RANGEs " rguenth at gcc dot gnu dot org
2006-12-28 20:33 ` rguenth at gcc dot gnu dot org
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