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  1. JDK
  2. JDK-8252372

Check if cloning is required to move loads out of loops in PhaseIdealLoop::split_if_with_blocks_post()

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Details

    • Enhancement
    • Resolution: Fixed
    • P3
    • 17
    • 16, 17
    • hotspot
    • b24

    Description

      While working on JDK-8249607 it was not clear if the code starting at L1399:

       // See if a shared loop-varying computation has no loop-varying uses.
        // Happens if something is only used for JVM state in uncommon trap exits,
        // like various versions of induction variable+offset. Clone the
        // computation per usage to allow it to sink out of the loop.
        if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)

      is really doing what it is supposed to do. There are several things to be checked and might to be reworked:
      - Revisit the entire cloning optimization:
        - Is it really required or would other loop opts move loads out of the loop anyways if there are no uses inside?
        - What if there are some uses inside and outside, is it really beneficial to do the cloning and possibly ending up with multiple loads?
      If optimization is required:
      - We should rethink the yanking part as it does not prevent the nodes to be put back on the worklist and might block some optimizations. Is there another way to prevent nodes without control to float back into the loop? Maybe adding a cast node with an explicit control?
      - Make sure to not pin loads inside the loop if x_ctrl turns out to be a node inside the loop at the end (if that is not already guaranteed)
      - Make sure not to pin loads in an outer strip mined loop if they do not have a use there (i.e. think about late_load_ctrl, maybe have a look at idea in
      http://cr.openjdk.java.net/~chagedorn/8249607/webrev.01/ which tackles that problem)

      Attachments

        Issue Links

          duplicates

          Enhancement - null JDK-8229015 Check removal of yank() in PhaseIdealLoop::split_if_with_blocks_post

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Closed
          relates to

          Bug - A problem which impairs or prevents the functions of the product. JDK-8260709 C2: assert(false) failed: unscheduable graph

          • P2 - Crashes, loss of data, severe memory leak.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8271954 C2: assert(false) failed: Bad graph detected in build_loop_late

          • P2 - Crashes, loss of data, severe memory leak.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8229483 Sinking load out of loop may trigger: assert(found_sfpt) failed: no node in loop that's not input to safepoint

          • P3 - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8249607 C2: assert(!had_error) failed: bad dominance

          • P3 - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8260420 C2 compilation fails with assert(found_sfpt) failed: no node in loop that's not input to safepoint

          • P3 - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8272562 C2: assert(false) failed: Bad graph detected in build_loop_late

          • P3 - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8274074 SIGFPE with C2 compiled code with -XX:+StressGCM

          • P3 - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8276846 JDK-8273416 is incomplete for UseSSE=1

          • P3 - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8308103 Massive (up to ~30x) increase in C2 compilation time since JDK 17

          • P3 - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8315377 C2: assert(u->find_out_with(Op_AddP) == nullptr) failed: more than 2 chained AddP nodes?

          • P3 - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8267988 C2: assert(!addp->is_AddP() || addp->in(AddPNode::Base)->is_top() || addp->in(AddPNode::Base) == n->in(AddPNode::Base)) failed: Base pointers must match (addp 1301)

          • P2 - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. JDK-8269088 C2 fails with assert(!n->is_Store() && !n->is_LoadStore()) failed: no node with a side effect

          • P2 - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. JDK-8269752 C2: assert(false) failed: Bad graph detected in build_loop_late

          • P2 - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. JDK-8269797 C2: assert(!in->is_CFG()) failed: CFG Node with no controlling input after JDK-8252372

          • P2 - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. JDK-8270296 C2: Another assert(!had_error) failed: bad dominance

          • P2 - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. JDK-8293941 C2: assert(false) failed: Bad graph detected in build_loop_late

          • P3 - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. JDK-8271600 C2: CheckCastPP which should closely follow Allocate is sunk of a loop

          • P3 - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8273416 C2: assert(false) failed: bad AD file after JDK-8252372 with UseSSE={0,1}

          • P3 - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8276064 CheckCastPP with raw oop input floats below a safepoint

          • P3 - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8280600 C2: assert(!had_error) failed: bad dominance

          • P3 - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8280696 C2 compilation hits assert(is_dominator(c, n_ctrl)) failed

          • P3 - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8286625 C2 fails with assert(!n->is_Store() && !n->is_LoadStore()) failed: no node with a side effect

          • P3 - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8290850 C2: create_new_if_for_predicate() does not clone pinned phi input nodes resulting in a broken graph

          • P3 - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8335709 C2: assert(!loop->is_member(get_loop(useblock))) failed: must be outside loop

          • P3 - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8273115 CountedLoopEndNode::stride_con crash in debug build with -XX:+TraceLoopOpts

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8268017 C2: assert(phi_type->isa_int() || phi_type->isa_ptr() || phi_type->isa_long()) failed: bad phi type

          • P2 - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. JDK-8269575 C2: assert(false) failed: graph should be schedulable after JDK-8252372

          • P2 - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. JDK-8270307 C2: assert(false) failed: bad AD file after JDK-8267687

          • P2 - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. JDK-8277529 SIGSEGV in C2 CompilerThread Node::rematerialize() compiling Packet::readUnsignedTrint

          • P2 - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. JDK-8313262 C2: Sinking node may cause required cast to be dropped

          • P2 - Crashes, loss of data, severe memory leak.
          • Closed
          links to

          Commit Commit openjdk/jdk/9d305b9c

          Review Review openjdk/jdk/3689

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            People

              roland Roland Westrelin
              chagedorn Christian Hagedorn
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              Dates

                Created:
                Updated:
                Resolved: