On 3/1/19 10:49 AM, Qing Zhao wrote: > Jeff, > > thanks a lot for the reply. > > this is really helpful. > > I double checked the dumped intermediate file for pass “dom3", and > located the following for _152: > > ****BEFORE the pass “dom3”, there is no _152, the corresponding Block > looks like: > > <bb 4> [local count: 12992277]: > _98 = (int) ufcMSR_52(D); > k_105 = (sword) ufcMSR_52(D); > i_49 = _98 > 0 ? k_105 : 0; > > ***During the pass “doms”, _152 is generated as following: > > Optimizing block #4 > …. > Visiting statement: > i_49 = _98 > 0 ? k_105 : 0; > Meeting > [0, 65535] > and > [0, 0] > to > [0, 65535] > Intersecting > [0, 65535] > and > [0, 65535] > to > [0, 65535] > Optimizing statement i_49 = _98 > 0 ? k_105 : 0; > Replaced 'k_105' with variable '_98' > gimple_simplified to _152 = MAX_EXPR <_98, 0>; > i_49 = _152; > Folded to: i_49 = _152; > LKUP STMT i_49 = _152 > ==== ASGN i_49 = _152 > > then bb 4 becomes: > > <bb 4> [local count: 12992277]: > _98 = (int) ufcMSR_52(D); > k_105 = _98; > _152 = MAX_EXPR <_98, 0>; > i_49 = _152; > > and all the i_49 are replaced with _152. > > However, the value range info for _152 doesnot reflect the one for i_49, > it keeps as UNDEFINED. > > is this the root problem? Yes, I think so. It's like we didn't record anything for _152 when we simplified the RHS to a MAX_EXPR.
Jeff
