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[vm] Remove the branch from pointer decompression in the runtime.

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In particular, this removes the branch from Deserializer::Ref.

Startup.ReadProgramSnapshot(StartupTime): on a Moto x4
  arm64c 46063 -> 44714 us (-2.93%)

TEST=ci
Change-Id: I1cdd6e8b36ad695f15552ebea0f3fc726b467863
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/242500
Reviewed-by: Liam Appelbe <liama@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
This commit is contained in:
Ryan Macnak 2022-05-02 19:25:12 +00:00 committed by Commit Bot
parent 017393ecdc
commit 49c039b5ab
2 changed files with 21 additions and 14 deletions
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5
runtime/vm/object.h
View file

@ -9260,11 +9260,6 @@ class Smi : public Integer {
return raw_smi;
}
static SmiPtr FromAlignedAddress(uword address) {
ASSERT((address & kSmiTagMask) == kSmiTag);
return static_cast<SmiPtr>(address);
}
static ClassPtr Class();
static intptr_t Value(const SmiPtr raw_smi) { return RawSmiValue(raw_smi); }

30
runtime/vm/tagged_pointer.h
View file

@ -9,6 +9,7 @@
#include "platform/assert.h"
#include "platform/utils.h"
#include "vm/class_id.h"
#include "vm/globals.h"
#include "vm/pointer_tagging.h"
namespace dart {
@ -66,13 +67,29 @@ class UntaggedObject;
return (addr & kObjectAlignmentMask) != kOldObjectBits; \
} \
\
bool operator==(const type& other) { return ptr == other.ptr; } \
bool operator!=(const type& other) { return ptr != other.ptr; } \
bool operator==(const type& other) { \
return (ptr & kSmiTagMask) == kHeapObjectTag \
? ptr == other.ptr \
: static_cast<compressed_uword>(ptr) == \
static_cast<compressed_uword>(other.ptr); \
} \
bool operator!=(const type& other) { \
return (ptr & kSmiTagMask) == kHeapObjectTag \
? ptr != other.ptr \
: static_cast<compressed_uword>(ptr) != \
static_cast<compressed_uword>(other.ptr); \
} \
constexpr bool operator==(const type& other) const { \
return ptr == other.ptr; \
return (ptr & kSmiTagMask) == kHeapObjectTag \
? ptr == other.ptr \
: static_cast<compressed_uword>(ptr) == \
static_cast<compressed_uword>(other.ptr); \
} \
constexpr bool operator!=(const type& other) const { \
return ptr != other.ptr; \
return (ptr & kSmiTagMask) == kHeapObjectTag \
? ptr != other.ptr \
: static_cast<compressed_uword>(ptr) != \
static_cast<compressed_uword>(other.ptr); \
}
class ObjectPtr {
@ -251,11 +268,6 @@ class CompressedObjectPtr {
: compressed_pointer_(static_cast<uint32_t>(tagged)) {}
ObjectPtr Decompress(uword heap_base) const {
if ((compressed_pointer_ & kSmiTagMask) != kHeapObjectTag) {
// TODO(liama): Make all native code robust to junk in the upper 32-bits
// of SMIs, then remove this special casing.
return DecompressSmi();
}
return static_cast<ObjectPtr>(static_cast<uword>(compressed_pointer_) +
heap_base);
}