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[regalloc] Do not pick state from ranges end before the predecessor does

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When pick state from predecessor, we should consider live ranges that were split out by the backwards spilling heurisitics and already end before the predecessor does.

Bug: chromium:1066869
Change-Id: I9ff85e73059a7c07f1e212fdc041450c79a4d70c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2174337
Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Yolanda Chen <yolanda.chen@intel.com>
Cr-Commit-Position: refs/heads/master@{#67665}
This commit is contained in:
Yolanda Chen 2020-05-06 23:18:54 +08:00 committed by Commit Bot
parent 1d8d67426e
commit f2fe2c678d
1 changed files with 8 additions and 4 deletions
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12
src/compiler/backend/register-allocator.cc
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@ -3848,11 +3848,15 @@ void LinearScanAllocator::AllocateRegisters() {
auto& spill_state = data()->GetSpillState(pred);
TRACE("Not a fallthrough. Adding %zu elements...\n",
spill_state.size());
LifetimePosition pred_end =
LifetimePosition::GapFromInstructionIndex(
this->code()->InstructionBlockAt(pred)->code_end());
for (const auto range : spill_state) {
// Filter out ranges that had their register stolen by backwards
// working spill heuristics. These have been spilled after the
// fact, so ignore them.
if (!range->HasRegisterAssigned()) continue;
// Filter out ranges that were split or had their register
// stolen by backwards working spill heuristics. These have
// been spilled after the fact, so ignore them.
if (range->End() < pred_end || !range->HasRegisterAssigned())
continue;
to_be_live->emplace(range);
}
}