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Bug 1186006 - Assert that all blocks have an entry resume point, excepts for unreachable one added by the Value Numbering. r=sunfish

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This commit is contained in:
Nicolas B. Pierron 2016-03-15 16:55:43 +00:00
parent 3a24c0c1be
commit a69cc3e5ee
3 changed files with 26 additions and 3 deletions
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12
js/src/jit/Lowering.cpp
View File

@ -4682,7 +4682,13 @@ LIRGenerator::updateResumeState(MInstruction* ins)
void
LIRGenerator::updateResumeState(MBasicBlock* block)
{
MOZ_ASSERT_IF(!mir()->compilingAsmJS(), block->entryResumePoint());
// As Value Numbering phase can remove edges from the entry basic block to a
// code paths reachable from the OSR entry point, we have to add fixup
// blocks to keep the dominator tree organized the same way. These fixup
// blocks are flaged as unreachable, and should only exist iff the graph has
// an OSR block.
MOZ_ASSERT_IF(!mir()->compilingAsmJS() && !block->unreachable(), block->entryResumePoint());
MOZ_ASSERT_IF(block->unreachable(), block->graph().osrBlock());
lastResumePoint_ = block->entryResumePoint();
if (JitSpewEnabled(JitSpew_IonSnapshots) && lastResumePoint_)
SpewResumePoint(block, nullptr, lastResumePoint_);
@ -4696,6 +4702,10 @@ LIRGenerator::visitBlock(MBasicBlock* block)
definePhis();
// See fixup blocks added by Value Numbering, to keep the dominator relation
// modified by the presence of the OSR block.
MOZ_ASSERT_IF(block->unreachable(), *block->begin() == block->lastIns());
MOZ_ASSERT_IF(block->unreachable(), block->graph().osrBlock());
for (MInstructionIterator iter = block->begin(); *iter != block->lastIns(); iter++) {
if (!visitInstruction(*iter))
return false;

16
js/src/jit/RangeAnalysis.cpp
View File

@ -2275,13 +2275,16 @@ RangeAnalysis::analyze()
for (ReversePostorderIterator iter(graph_.rpoBegin()); iter != graph_.rpoEnd(); iter++) {
MBasicBlock* block = *iter;
MOZ_ASSERT(!block->unreachable());
// No blocks are supposed to be unreachable, except when we have an OSR
// block, in which case the Value Numbering phase add fixup blocks which
// are unreachable.
MOZ_ASSERT(!block->unreachable() || graph_.osrBlock());
// If the block's immediate dominator is unreachable, the block is
// unreachable. Iterating in RPO, we'll always see the immediate
// dominator before the block.
if (block->immediateDominator()->unreachable()) {
block->setUnreachable();
block->setUnreachableUnchecked();
continue;
}
@ -3430,6 +3433,15 @@ RangeAnalysis::prepareForUCE(bool* shouldRemoveDeadCode)
if (!block->unreachable())
continue;
// Filter out unreachable fake entries.
if (block->numPredecessors() == 0) {
// Ignore fixup blocks added by the Value Numbering phase, in order
// to keep the dominator tree as-is when we have OSR Block which are
// no longer reachable from the main entry point of the graph.
MOZ_ASSERT(graph_.osrBlock());
continue;
}
MControlInstruction* cond = block->getPredecessor(0)->lastIns();
if (!cond->isTest())
continue;

1
js/src/jit/ValueNumbering.cpp
View File

@ -440,6 +440,7 @@ ValueNumberer::fixupOSROnlyLoop(MBasicBlock* block, MBasicBlock* backedge)
fake->setImmediateDominator(fake);
fake->addNumDominated(1);
fake->setDomIndex(fake->id());
fake->setUnreachable();
// Create zero-input phis to use as inputs for any phis in |block|.
// Again, this is a little odd, but it's the least-odd thing we can do