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MIPS: Fix deoptimization entry table when branch cannot reach.

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This fixes failures when table has more than 8192 entries, and preserves
optimization to have 2 instructions per entry.

TEST=mozilla/regress-398085-01
BUG=
R=paul.lind@imgtec.com

Review URL: https://codereview.chromium.org/477623002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23131 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
dusan.milosavljevic@imgtec.com 2014-08-14 15:23:01 +00:00
parent 5c7edb7e2b
commit 6dee88849a
1 changed files with 50 additions and 13 deletions
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39
src/mips/deoptimizer-mips.cc
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@ -324,8 +324,13 @@ void Deoptimizer::TableEntryGenerator::GeneratePrologue() {
// Create a sequence of deoptimization entries.
// Note that registers are still live when jumping to an entry.
Label table_start, done;
Label table_start, done, done_special, trampoline_jump;
__ bind(&table_start);
int kMaxEntriesBranchReach = (1 << (kImm16Bits - 2))/
(table_entry_size_ / Assembler::kInstrSize);
if (count() <= kMaxEntriesBranchReach) {
// Common case.
for (int i = 0; i < count(); i++) {
Label start;
__ bind(&start);
@ -340,6 +345,38 @@ void Deoptimizer::TableEntryGenerator::GeneratePrologue() {
count() * table_entry_size_);
__ bind(&done);
__ Push(at);
} else {
// Uncommon case, the branch cannot reach.
// Create mini trampoline and adjust id constants to get proper value at
// the end of table.
for (int i = kMaxEntriesBranchReach; i > 1; i--) {
Label start;
__ bind(&start);
DCHECK(is_int16(i));
__ Branch(USE_DELAY_SLOT, &trampoline_jump); // Expose delay slot.
__ li(at, - i); // In the delay slot.
DCHECK_EQ(table_entry_size_, masm()->SizeOfCodeGeneratedSince(&start));
}
// Entry with id == kMaxEntriesBranchReach - 1.
__ bind(&trampoline_jump);
__ Branch(USE_DELAY_SLOT, &done_special);
__ li(at, -1);
for (int i = kMaxEntriesBranchReach ; i < count(); i++) {
Label start;
__ bind(&start);
DCHECK(is_int16(i));
__ Branch(USE_DELAY_SLOT, &done); // Expose delay slot.
__ li(at, i); // In the delay slot.
}
DCHECK_EQ(masm()->SizeOfCodeGeneratedSince(&table_start),
count() * table_entry_size_);
__ bind(&done_special);
__ addiu(at, at, kMaxEntriesBranchReach);
__ bind(&done);
__ Push(at);
}
}