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Unified Diff: src/assembler.cc

Issue 6902066: Add AST ID to RelocInfo for type-recording ICs. Changes 7644 and 7632, combined. (Closed) Base URL: https://v8.googlecode.com/svn/branches/bleeding_edge
Patch Set: Fix an issue where a switch statement label ID could be used for both a load IC and a compare IC. Created 9 years, 8 months ago
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Index: src/assembler.cc
diff --git a/src/assembler.cc b/src/assembler.cc
index ca30e19cb4d2d1544cb2d1778a80af7d1e997e14..77c7b68c4f799bd1417e7dd5ad838f4a6090e2b1 100644
--- a/src/assembler.cc
+++ b/src/assembler.cc
@@ -30,7 +30,7 @@
// The original source code covered by the above license above has been
// modified significantly by Google Inc.
-// Copyright 2006-2009 the V8 project authors. All rights reserved.
+// Copyright 2011 the V8 project authors. All rights reserved.
#include "v8.h"
@@ -87,58 +87,85 @@ int Label::pos() const {
// -----------------------------------------------------------------------------
// Implementation of RelocInfoWriter and RelocIterator
//
+// Relocation information is written backwards in memory, from high addresses
+// towards low addresses, byte by byte. Therefore, in the encodings listed
+// below, the first byte listed it at the highest address, and successive
+// bytes in the record are at progressively lower addresses.
+//
// Encoding
//
// The most common modes are given single-byte encodings. Also, it is
// easy to identify the type of reloc info and skip unwanted modes in
// an iteration.
//
-// The encoding relies on the fact that there are less than 14
-// different relocation modes.
-//
-// embedded_object: [6 bits pc delta] 00
-//
-// code_taget: [6 bits pc delta] 01
+// The encoding relies on the fact that there are fewer than 14
+// different non-compactly encoded relocation modes.
//
-// position: [6 bits pc delta] 10,
-// [7 bits signed data delta] 0
+// The first byte of a relocation record has a tag in its low 2 bits:
+// Here are the record schemes, depending on the low tag and optional higher
+// tags.
//
-// statement_position: [6 bits pc delta] 10,
-// [7 bits signed data delta] 1
+// Low tag:
+// 00: embedded_object: [6-bit pc delta] 00
//
-// any nondata mode: 00 [4 bits rmode] 11, // rmode: 0..13 only
-// 00 [6 bits pc delta]
+// 01: code_target: [6-bit pc delta] 01
//
-// pc-jump: 00 1111 11,
-// 00 [6 bits pc delta]
+// 10: short_data_record: [6-bit pc delta] 10 followed by
+// [6-bit data delta] [2-bit data type tag]
//
-// pc-jump: 01 1111 11,
-// (variable length) 7 - 26 bit pc delta, written in chunks of 7
-// bits, the lowest 7 bits written first.
+// 11: long_record [2-bit high tag][4 bit middle_tag] 11
+// followed by variable data depending on type.
//
-// data-jump + pos: 00 1110 11,
-// signed intptr_t, lowest byte written first
+// 2-bit data type tags, used in short_data_record and data_jump long_record:
+// code_target_with_id: 00
+// position: 01
+// statement_position: 10
+// comment: 11 (not used in short_data_record)
//
-// data-jump + st.pos: 01 1110 11,
-// signed intptr_t, lowest byte written first
+// Long record format:
+// 4-bit middle_tag:
+// 0000 - 1100 : Short record for RelocInfo::Mode middle_tag + 2
+// (The middle_tag encodes rmode - RelocInfo::LAST_COMPACT_ENUM,
+// and is between 0000 and 1100)
+// The format is:
+// 00 [4 bit middle_tag] 11 followed by
+// 00 [6 bit pc delta]
//
-// data-jump + comm.: 10 1110 11,
-// signed intptr_t, lowest byte written first
+// 1101: not used (would allow one more relocation mode to be added)
+// 1110: long_data_record
+// The format is: [2-bit data_type_tag] 1110 11
+// signed intptr_t, lowest byte written first
+// (except data_type code_target_with_id, which
+// is followed by a signed int, not intptr_t.)
//
+// 1111: long_pc_jump
+// The format is:
+// pc-jump: 00 1111 11,
+// 00 [6 bits pc delta]
+// or
+// pc-jump (variable length):
+// 01 1111 11,
+// [7 bits data] 0
+// ...
+// [7 bits data] 1
+// (Bits 6..31 of pc delta, with leading zeroes
+// dropped, and last non-zero chunk tagged with 1.)
+
+
const int kMaxRelocModes = 14;
const int kTagBits = 2;
const int kTagMask = (1 << kTagBits) - 1;
const int kExtraTagBits = 4;
-const int kPositionTypeTagBits = 1;
-const int kSmallDataBits = kBitsPerByte - kPositionTypeTagBits;
+const int kLocatableTypeTagBits = 2;
+const int kSmallDataBits = kBitsPerByte - kLocatableTypeTagBits;
const int kEmbeddedObjectTag = 0;
const int kCodeTargetTag = 1;
-const int kPositionTag = 2;
+const int kLocatableTag = 2;
const int kDefaultTag = 3;
-const int kPCJumpTag = (1 << kExtraTagBits) - 1;
+const int kPCJumpExtraTag = (1 << kExtraTagBits) - 1;
const int kSmallPCDeltaBits = kBitsPerByte - kTagBits;
const int kSmallPCDeltaMask = (1 << kSmallPCDeltaBits) - 1;
@@ -152,11 +179,12 @@ const int kLastChunkTagMask = 1;
const int kLastChunkTag = 1;
-const int kDataJumpTag = kPCJumpTag - 1;
+const int kDataJumpExtraTag = kPCJumpExtraTag - 1;
-const int kNonstatementPositionTag = 0;
-const int kStatementPositionTag = 1;
-const int kCommentTag = 2;
+const int kCodeWithIdTag = 0;
+const int kNonstatementPositionTag = 1;
+const int kStatementPositionTag = 2;
+const int kCommentTag = 3;
uint32_t RelocInfoWriter::WriteVariableLengthPCJump(uint32_t pc_delta) {
@@ -164,7 +192,7 @@ uint32_t RelocInfoWriter::WriteVariableLengthPCJump(uint32_t pc_delta) {
// Otherwise write a variable length PC jump for the bits that do
// not fit in the kSmallPCDeltaBits bits.
if (is_uintn(pc_delta, kSmallPCDeltaBits)) return pc_delta;
- WriteExtraTag(kPCJumpTag, kVariableLengthPCJumpTopTag);
+ WriteExtraTag(kPCJumpExtraTag, kVariableLengthPCJumpTopTag);
uint32_t pc_jump = pc_delta >> kSmallPCDeltaBits;
ASSERT(pc_jump > 0);
// Write kChunkBits size chunks of the pc_jump.
@@ -187,7 +215,7 @@ void RelocInfoWriter::WriteTaggedPC(uint32_t pc_delta, int tag) {
void RelocInfoWriter::WriteTaggedData(intptr_t data_delta, int tag) {
- *--pos_ = static_cast<byte>(data_delta << kPositionTypeTagBits | tag);
+ *--pos_ = static_cast<byte>(data_delta << kLocatableTypeTagBits | tag);
}
@@ -206,11 +234,20 @@ void RelocInfoWriter::WriteExtraTaggedPC(uint32_t pc_delta, int extra_tag) {
}
+void RelocInfoWriter::WriteExtraTaggedIntData(int data_delta, int top_tag) {
+ WriteExtraTag(kDataJumpExtraTag, top_tag);
+ for (int i = 0; i < kIntSize; i++) {
+ *--pos_ = static_cast<byte>(data_delta);
+ // Signed right shift is arithmetic shift. Tested in test-utils.cc.
+ data_delta = data_delta >> kBitsPerByte;
+ }
+}
+
void RelocInfoWriter::WriteExtraTaggedData(intptr_t data_delta, int top_tag) {
- WriteExtraTag(kDataJumpTag, top_tag);
+ WriteExtraTag(kDataJumpExtraTag, top_tag);
for (int i = 0; i < kIntptrSize; i++) {
*--pos_ = static_cast<byte>(data_delta);
- // Signed right shift is arithmetic shift. Tested in test-utils.cc.
+ // Signed right shift is arithmetic shift. Tested in test-utils.cc.
data_delta = data_delta >> kBitsPerByte;
}
}
@@ -221,7 +258,8 @@ void RelocInfoWriter::Write(const RelocInfo* rinfo) {
byte* begin_pos = pos_;
#endif
ASSERT(rinfo->pc() - last_pc_ >= 0);
- ASSERT(RelocInfo::NUMBER_OF_MODES <= kMaxRelocModes);
+ ASSERT(RelocInfo::NUMBER_OF_MODES - RelocInfo::LAST_COMPACT_ENUM <=
+ kMaxRelocModes);
// Use unsigned delta-encoding for pc.
uint32_t pc_delta = static_cast<uint32_t>(rinfo->pc() - last_pc_);
RelocInfo::Mode rmode = rinfo->rmode();
@@ -232,35 +270,48 @@ void RelocInfoWriter::Write(const RelocInfo* rinfo) {
} else if (rmode == RelocInfo::CODE_TARGET) {
WriteTaggedPC(pc_delta, kCodeTargetTag);
ASSERT(begin_pos - pos_ <= RelocInfo::kMaxCallSize);
+ } else if (rmode == RelocInfo::CODE_TARGET_WITH_ID) {
+ // Use signed delta-encoding for id.
+ ASSERT(static_cast<int>(rinfo->data()) == rinfo->data());
+ int id_delta = static_cast<int>(rinfo->data()) - last_id_;
+ // Check if delta is small enough to fit in a tagged byte.
+ if (is_intn(id_delta, kSmallDataBits)) {
+ WriteTaggedPC(pc_delta, kLocatableTag);
+ WriteTaggedData(id_delta, kCodeWithIdTag);
+ } else {
+ // Otherwise, use costly encoding.
+ WriteExtraTaggedPC(pc_delta, kPCJumpExtraTag);
+ WriteExtraTaggedIntData(id_delta, kCodeWithIdTag);
+ }
+ last_id_ = static_cast<int>(rinfo->data());
} else if (RelocInfo::IsPosition(rmode)) {
- // Use signed delta-encoding for data.
- intptr_t data_delta = rinfo->data() - last_data_;
- int pos_type_tag = rmode == RelocInfo::POSITION ? kNonstatementPositionTag
- : kStatementPositionTag;
- // Check if data is small enough to fit in a tagged byte.
- // We cannot use is_intn because data_delta is not an int32_t.
- if (data_delta >= -(1 << (kSmallDataBits-1)) &&
- data_delta < 1 << (kSmallDataBits-1)) {
- WriteTaggedPC(pc_delta, kPositionTag);
- WriteTaggedData(data_delta, pos_type_tag);
- last_data_ = rinfo->data();
+ // Use signed delta-encoding for position.
+ ASSERT(static_cast<int>(rinfo->data()) == rinfo->data());
+ int pos_delta = static_cast<int>(rinfo->data()) - last_position_;
+ int pos_type_tag = (rmode == RelocInfo::POSITION) ? kNonstatementPositionTag
+ : kStatementPositionTag;
+ // Check if delta is small enough to fit in a tagged byte.
+ if (is_intn(pos_delta, kSmallDataBits)) {
+ WriteTaggedPC(pc_delta, kLocatableTag);
+ WriteTaggedData(pos_delta, pos_type_tag);
} else {
// Otherwise, use costly encoding.
- WriteExtraTaggedPC(pc_delta, kPCJumpTag);
- WriteExtraTaggedData(data_delta, pos_type_tag);
- last_data_ = rinfo->data();
+ WriteExtraTaggedPC(pc_delta, kPCJumpExtraTag);
+ WriteExtraTaggedIntData(pos_delta, pos_type_tag);
}
+ last_position_ = static_cast<int>(rinfo->data());
} else if (RelocInfo::IsComment(rmode)) {
// Comments are normally not generated, so we use the costly encoding.
- WriteExtraTaggedPC(pc_delta, kPCJumpTag);
- WriteExtraTaggedData(rinfo->data() - last_data_, kCommentTag);
- last_data_ = rinfo->data();
+ WriteExtraTaggedPC(pc_delta, kPCJumpExtraTag);
+ WriteExtraTaggedData(rinfo->data(), kCommentTag);
ASSERT(begin_pos - pos_ >= RelocInfo::kMinRelocCommentSize);
} else {
+ ASSERT(rmode > RelocInfo::LAST_COMPACT_ENUM);
+ int saved_mode = rmode - RelocInfo::LAST_COMPACT_ENUM;
// For all other modes we simply use the mode as the extra tag.
// None of these modes need a data component.
- ASSERT(rmode < kPCJumpTag && rmode < kDataJumpTag);
- WriteExtraTaggedPC(pc_delta, rmode);
+ ASSERT(saved_mode < kPCJumpExtraTag && saved_mode < kDataJumpExtraTag);
+ WriteExtraTaggedPC(pc_delta, saved_mode);
}
last_pc_ = rinfo->pc();
#ifdef DEBUG
@@ -294,12 +345,32 @@ inline void RelocIterator::AdvanceReadPC() {
}
+void RelocIterator::AdvanceReadId() {
+ int x = 0;
+ for (int i = 0; i < kIntSize; i++) {
+ x |= static_cast<int>(*--pos_) << i * kBitsPerByte;
+ }
+ last_id_ += x;
+ rinfo_.data_ = last_id_;
+}
+
+
+void RelocIterator::AdvanceReadPosition() {
+ int x = 0;
+ for (int i = 0; i < kIntSize; i++) {
+ x |= static_cast<int>(*--pos_) << i * kBitsPerByte;
+ }
+ last_position_ += x;
+ rinfo_.data_ = last_position_;
+}
+
+
void RelocIterator::AdvanceReadData() {
intptr_t x = 0;
for (int i = 0; i < kIntptrSize; i++) {
x |= static_cast<intptr_t>(*--pos_) << i * kBitsPerByte;
}
- rinfo_.data_ += x;
+ rinfo_.data_ = x;
}
@@ -319,27 +390,33 @@ void RelocIterator::AdvanceReadVariableLengthPCJump() {
}
-inline int RelocIterator::GetPositionTypeTag() {
- return *pos_ & ((1 << kPositionTypeTagBits) - 1);
+inline int RelocIterator::GetLocatableTypeTag() {
+ return *pos_ & ((1 << kLocatableTypeTagBits) - 1);
}
-inline void RelocIterator::ReadTaggedData() {
+inline void RelocIterator::ReadTaggedId() {
int8_t signed_b = *pos_;
// Signed right shift is arithmetic shift. Tested in test-utils.cc.
- rinfo_.data_ += signed_b >> kPositionTypeTagBits;
+ last_id_ += signed_b >> kLocatableTypeTagBits;
+ rinfo_.data_ = last_id_;
}
-inline RelocInfo::Mode RelocIterator::DebugInfoModeFromTag(int tag) {
- if (tag == kStatementPositionTag) {
- return RelocInfo::STATEMENT_POSITION;
- } else if (tag == kNonstatementPositionTag) {
- return RelocInfo::POSITION;
- } else {
- ASSERT(tag == kCommentTag);
- return RelocInfo::COMMENT;
- }
+inline void RelocIterator::ReadTaggedPosition() {
+ int8_t signed_b = *pos_;
+ // Signed right shift is arithmetic shift. Tested in test-utils.cc.
+ last_position_ += signed_b >> kLocatableTypeTagBits;
+ rinfo_.data_ = last_position_;
+}
+
+
+static inline RelocInfo::Mode GetPositionModeFromTag(int tag) {
+ ASSERT(tag == kNonstatementPositionTag ||
+ tag == kStatementPositionTag);
+ return (tag == kNonstatementPositionTag) ?
+ RelocInfo::POSITION :
+ RelocInfo::STATEMENT_POSITION;
}
@@ -358,37 +435,64 @@ void RelocIterator::next() {
} else if (tag == kCodeTargetTag) {
ReadTaggedPC();
if (SetMode(RelocInfo::CODE_TARGET)) return;
- } else if (tag == kPositionTag) {
+ } else if (tag == kLocatableTag) {
ReadTaggedPC();
Advance();
- // Check if we want source positions.
- if (mode_mask_ & RelocInfo::kPositionMask) {
- ReadTaggedData();
- if (SetMode(DebugInfoModeFromTag(GetPositionTypeTag()))) return;
+ int locatable_tag = GetLocatableTypeTag();
+ if (locatable_tag == kCodeWithIdTag) {
+ if (SetMode(RelocInfo::CODE_TARGET_WITH_ID)) {
+ ReadTaggedId();
+ return;
+ }
+ } else {
+ // Compact encoding is never used for comments,
+ // so it must be a position.
+ ASSERT(locatable_tag == kNonstatementPositionTag ||
+ locatable_tag == kStatementPositionTag);
+ if (mode_mask_ & RelocInfo::kPositionMask) {
+ ReadTaggedPosition();
+ if (SetMode(GetPositionModeFromTag(locatable_tag))) return;
+ }
}
} else {
ASSERT(tag == kDefaultTag);
int extra_tag = GetExtraTag();
- if (extra_tag == kPCJumpTag) {
+ if (extra_tag == kPCJumpExtraTag) {
int top_tag = GetTopTag();
if (top_tag == kVariableLengthPCJumpTopTag) {
AdvanceReadVariableLengthPCJump();
} else {
AdvanceReadPC();
}
- } else if (extra_tag == kDataJumpTag) {
- // Check if we want debug modes (the only ones with data).
- if (mode_mask_ & RelocInfo::kDebugMask) {
- int top_tag = GetTopTag();
- AdvanceReadData();
- if (SetMode(DebugInfoModeFromTag(top_tag))) return;
+ } else if (extra_tag == kDataJumpExtraTag) {
+ int locatable_tag = GetTopTag();
+ if (locatable_tag == kCodeWithIdTag) {
+ if (SetMode(RelocInfo::CODE_TARGET_WITH_ID)) {
+ AdvanceReadId();
+ return;
+ }
+ Advance(kIntSize);
+ } else if (locatable_tag != kCommentTag) {
+ ASSERT(locatable_tag == kNonstatementPositionTag ||
+ locatable_tag == kStatementPositionTag);
+ if (mode_mask_ & RelocInfo::kPositionMask) {
+ AdvanceReadPosition();
+ if (SetMode(GetPositionModeFromTag(locatable_tag))) return;
+ } else {
+ Advance(kIntSize);
+ }
} else {
- // Otherwise, just skip over the data.
+ ASSERT(locatable_tag == kCommentTag);
+ if (SetMode(RelocInfo::COMMENT)) {
+ AdvanceReadData();
+ return;
+ }
Advance(kIntptrSize);
}
} else {
AdvanceReadPC();
- if (SetMode(static_cast<RelocInfo::Mode>(extra_tag))) return;
+ int rmode = extra_tag + RelocInfo::LAST_COMPACT_ENUM;
+ if (SetMode(static_cast<RelocInfo::Mode>(rmode))) return;
}
}
}
@@ -404,6 +508,8 @@ RelocIterator::RelocIterator(Code* code, int mode_mask) {
end_ = code->relocation_start();
done_ = false;
mode_mask_ = mode_mask;
+ last_id_ = 0;
+ last_position_ = 0;
if (mode_mask_ == 0) pos_ = end_;
next();
}
@@ -417,6 +523,8 @@ RelocIterator::RelocIterator(const CodeDesc& desc, int mode_mask) {
end_ = pos_ - desc.reloc_size;
done_ = false;
mode_mask_ = mode_mask;
+ last_id_ = 0;
+ last_position_ = 0;
if (mode_mask_ == 0) pos_ = end_;
next();
}
@@ -444,6 +552,8 @@ const char* RelocInfo::RelocModeName(RelocInfo::Mode rmode) {
return "debug break";
case RelocInfo::CODE_TARGET:
return "code target";
+ case RelocInfo::CODE_TARGET_WITH_ID:
+ return "code target with id";
case RelocInfo::GLOBAL_PROPERTY_CELL:
return "global property cell";
case RelocInfo::RUNTIME_ENTRY:
@@ -490,6 +600,9 @@ void RelocInfo::Print(FILE* out) {
Code* code = Code::GetCodeFromTargetAddress(target_address());
PrintF(out, " (%s) (%p)", Code::Kind2String(code->kind()),
target_address());
+ if (rmode_ == CODE_TARGET_WITH_ID) {
+ PrintF(" (id=%d)", static_cast<int>(data_));
+ }
} else if (IsPosition(rmode_)) {
PrintF(out, " (%" V8_PTR_PREFIX "d)", data());
} else if (rmode_ == RelocInfo::RUNTIME_ENTRY &&
@@ -523,6 +636,7 @@ void RelocInfo::Verify() {
#endif
case CONSTRUCT_CALL:
case CODE_TARGET_CONTEXT:
+ case CODE_TARGET_WITH_ID:
case CODE_TARGET: {
// convert inline target address to code object
Address addr = target_address();
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