Avoid excessive spill slots for slow paths.
Reducing the frame size makes stack maps smaller as we need
fewer bits for stack masks and some dex register locations
may use short location kind rather than long. On Nexus 9,
AOSP ToT, the boot.oat size reduction is
prebuilt multi-part boot image:
- 32-bit boot.oat: -416KiB (-0.6%)
- 64-bit boot.oat: -635KiB (-0.9%)
prebuilt multi-part boot image with read barrier:
- 32-bit boot.oat: -483KiB (-0.7%)
- 64-bit boot.oat: -703KiB (-0.9%)
on-device built single boot image:
- 32-bit boot.oat: -380KiB (-0.6%)
- 64-bit boot.oat: -632KiB (-0.9%)
on-device built single boot image with read barrier:
- 32-bit boot.oat: -448KiB (-0.6%)
- 64-bit boot.oat: -692KiB (-0.9%)
The other benefit is that at runtime, threads may need fewer
pages for their stacks, reducing overall memory usage.
We defer the calculation of the maximum spill size from
the main register allocator (linear scan or graph coloring)
to the RegisterAllocationResolver and do it based on the
live registers at slow path safepoints. The old notion of
an artificial slow path safepoint interval is removed as
it is no longer needed.
Test: Run ART test suite on host and Nexus 9.
Bug: 30212852
Change-Id: I40b3d114e278e2c5807982904fa49bf6642c6275
diff --git a/compiler/optimizing/ssa_liveness_analysis.h b/compiler/optimizing/ssa_liveness_analysis.h
index 92788fe..06785e1 100644
--- a/compiler/optimizing/ssa_liveness_analysis.h
+++ b/compiler/optimizing/ssa_liveness_analysis.h
@@ -208,11 +208,6 @@
return new (allocator) LiveInterval(allocator, type, instruction);
}
- static LiveInterval* MakeSlowPathInterval(ArenaAllocator* allocator, HInstruction* instruction) {
- return new (allocator) LiveInterval(
- allocator, Primitive::kPrimVoid, instruction, false, kNoRegister, false, true);
- }
-
static LiveInterval* MakeFixedInterval(ArenaAllocator* allocator, int reg, Primitive::Type type) {
return new (allocator) LiveInterval(allocator, type, nullptr, true, reg, false);
}
@@ -223,7 +218,6 @@
bool IsFixed() const { return is_fixed_; }
bool IsTemp() const { return is_temp_; }
- bool IsSlowPathSafepoint() const { return is_slow_path_safepoint_; }
// This interval is the result of a split.
bool IsSplit() const { return parent_ != this; }
@@ -790,7 +784,7 @@
DCHECK(!HasHighInterval());
DCHECK(!HasLowInterval());
high_or_low_interval_ = new (allocator_) LiveInterval(
- allocator_, type_, defined_by_, false, kNoRegister, is_temp, false, true);
+ allocator_, type_, defined_by_, false, kNoRegister, is_temp, true);
high_or_low_interval_->high_or_low_interval_ = this;
if (first_range_ != nullptr) {
high_or_low_interval_->first_range_ = first_range_->Dup(allocator_);
@@ -919,7 +913,6 @@
bool is_fixed = false,
int reg = kNoRegister,
bool is_temp = false,
- bool is_slow_path_safepoint = false,
bool is_high_interval = false)
: allocator_(allocator),
first_range_(nullptr),
@@ -936,7 +929,6 @@
spill_slot_(kNoSpillSlot),
is_fixed_(is_fixed),
is_temp_(is_temp),
- is_slow_path_safepoint_(is_slow_path_safepoint),
is_high_interval_(is_high_interval),
high_or_low_interval_(nullptr),
defined_by_(defined_by) {}
@@ -1121,9 +1113,6 @@
// Whether the interval is for a temporary.
const bool is_temp_;
- // Whether the interval is for a safepoint that calls on slow path.
- const bool is_slow_path_safepoint_;
-
// Whether this interval is a synthesized interval for register pair.
const bool is_high_interval_;