RFR(S): 8192992: Test8007294.java failed: attempted to spill a non-spillable item
vladimir.kozlov at oracle.com
Mon Mar 5 17:02:22 UTC 2018
Yes, it is legal workaround but this way you removed all subsuming loads
Should we do anti-dependency check for loads during matching when shared
nodes are marked?:
How expensive would be that?
On 3/5/18 7:50 AM, Nils Eliasson wrote:
> This patch is a workaround for a scheduling problem encountered in some
> rare circumstances. Instead of hitting the assert we retry the
> compilation without subsuming loads.
> To quote Tobias:
> "The crash happens because a testN_mem_reg0 (CmpN(LoadN(mem), NULL)) is
> scheduled in a different block than its jmpCon user and the register
> allocator tries to spill the flag register. The problem is that
> PhaseCFG::schedule_late() detects an anti-dependency for the
> testN_mem_reg0 on a bottom memory Phi and therefore raises the LCA to
> the early block (see PhaseCFG::insert_anti_dependences()) which is "far
> away" from its jmpCon user. "
> Thanks to Roland who suggested the workaround.
More information about the hotspot-compiler-dev