Reviewers: danno, Paul Lind, kisg, fschneider, Kasper Lund,
Description:
MIPS: Re-worked the deopt entry table.
This method works around the Branch offset and relocinfo issues by
emulating a
pc-relative jump.
This allows us to generate larger entry tables. The theoretical limit is
2^16
(number of entries)
but even that can be extended by allowing a larger instruction count.
Also reverted the mips-specific constant (kNumberOfEntries) in deoptimizer.h
BUG=
TEST=
Please review this at http://codereview.chromium.org/9347016/
Affected files:
M src/deoptimizer.h
M src/mips/deoptimizer-mips.cc
Index: src/deoptimizer.h
diff --git a/src/deoptimizer.h b/src/deoptimizer.h
index
44189d96cd7774e4482acd6bd7d75556e1f5893b..68bc48d5cbbbb9f83b6c22d9db20d3fea7103a89
100644
--- a/src/deoptimizer.h
+++ b/src/deoptimizer.h
@@ -267,11 +267,7 @@ class Deoptimizer : public Malloced {
int ConvertJSFrameIndexToFrameIndex(int jsframe_index);
private:
-#ifdef V8_TARGET_ARCH_MIPS
- static const int kNumberOfEntries = 4096;
-#else
static const int kNumberOfEntries = 16384;
-#endif
Deoptimizer(Isolate* isolate,
JSFunction* function,
Index: src/mips/deoptimizer-mips.cc
diff --git a/src/mips/deoptimizer-mips.cc b/src/mips/deoptimizer-mips.cc
index
26a406333f732b8192131cdf73748ed37c897350..78720f4403d5859fabaa51a34dde42e6d69a8bc4
100644
--- a/src/mips/deoptimizer-mips.cc
+++ b/src/mips/deoptimizer-mips.cc
@@ -36,9 +36,6 @@ namespace v8 {
namespace internal {
-const int Deoptimizer::table_entry_size_ = 32;
-
-
int Deoptimizer::patch_size() {
const int kCallInstructionSizeInWords = 4;
return kCallInstructionSizeInWords * Assembler::kInstrSize;
@@ -839,32 +836,55 @@ void Deoptimizer::EntryGenerator::Generate() {
}
+// Maximum size of a table entry generated below.
+const int Deoptimizer::table_entry_size_ = 12 * Assembler::kInstrSize;
+
void Deoptimizer::TableEntryGenerator::GeneratePrologue() {
Assembler::BlockTrampolinePoolScope block_trampoline_pool(masm());
// Create a sequence of deoptimization entries. Note that any
// registers may be still live.
-
- Label done;
+ Label table_start;
+ __ bind(&table_start);
for (int i = 0; i < count(); i++) {
- int start = masm()->pc_offset();
- USE(start);
+ Label start;
+ __ bind(&start);
if (type() != EAGER) {
// Emulate ia32 like call by pushing return address to stack.
- __ push(ra);
+ __ addiu(sp, sp, -3 * kPointerSize);
+ __ sw(ra, MemOperand(sp, 2 * kPointerSize));
+ } else {
+ __ addiu(sp, sp, -2 * kPointerSize);
}
- __ li(at, Operand(i));
- __ push(at);
- __ Branch(&done);
+ // Using ori makes sure only one instruction is generated. This will
work
+ // as long as the number of deopt entries is below 2^16.
+ __ ori(at, zero_reg, i);
+ __ sw(at, MemOperand(sp, kPointerSize));
+ __ sw(ra, MemOperand(sp, 0));
+ // This branch instruction only jumps over one instruction, and that is
+ // executed in the delay slot. The result is that execution is linear
but
+ // the ra register is updated.
+ __ bal(1);
+ // Jump over the remaining deopt entries (including this one).
+ // Only include the remaining part of the current entry in the
calculation.
+ const int remaining_entries = (count() - i) * table_entry_size_;
+ const int cur_size = masm()->SizeOfCodeGeneratedSince(&start);
+ // ra points to the instruction after the delay slot. Adjust by 4.
+ __ Addu(at, ra, remaining_entries - cur_size - Assembler::kInstrSize);
+ __ lw(ra, MemOperand(sp, 0));
+ __ jr(at); // Expose delay slot.
+ __ addiu(sp, sp, kPointerSize); // In delay slot.
// Pad the rest of the code.
- while (table_entry_size_ > (masm()->pc_offset() - start)) {
+ while (table_entry_size_ > (masm()->SizeOfCodeGeneratedSince(&start)))
{
__ nop();
}
- ASSERT_EQ(table_entry_size_, masm()->pc_offset() - start);
+ ASSERT_EQ(table_entry_size_, masm()->SizeOfCodeGeneratedSince(&start));
}
- __ bind(&done);
+
+ ASSERT_EQ(masm()->SizeOfCodeGeneratedSince(&table_start),
+ count() * table_entry_size_);
}
#undef __
--
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