Re: [PATCH] Disable an unsafe VRP transformation when -fno-strict-overflow is set

2014-11-20 Thread Richard Biener
On Thu, Nov 20, 2014 at 4:21 AM, Patrick Palka patr...@parcs.ath.cx wrote: VRP may simplify a conditional like i = 5 to i == 5 if it is known that the lower bound of i's range is 5, e.g. [5, +INF]. But if the upper bound of i's range is also overflow infinity, i.e. [5, +INF(OVF)] then this

[PATCH] Disable an unsafe VRP transformation when -fno-strict-overflow is set

2014-11-19 Thread Patrick Palka
VRP may simplify a conditional like i = 5 to i == 5 if it is known that the lower bound of i's range is 5, e.g. [5, +INF]. But if the upper bound of i's range is also overflow infinity, i.e. [5, +INF(OVF)] then this transformation is only valid if -fstrict-overflow is in effect. Likewise for

Re: [PATCH] Disable an unsafe VRP transformation when -fno-strict-overflow is set

2014-11-19 Thread Patrick Palka
On Wed, Nov 19, 2014 at 10:21 PM, Patrick Palka patr...@parcs.ath.cx wrote: VRP may simplify a conditional like i = 5 to i == 5 if it is known that the lower bound of i's range is 5, e.g. [5, +INF]. But if the upper bound of i's range is also overflow infinity, i.e. [5, +INF(OVF)] then this