[v8-dev] [arm] Decrease the size of the assembler class by allocating buffers of pending constants on the he… (issue 1309903009 by ishell@chromium.org)

Fri, 04 Sep 2015 07:55:24 -0700 

Reviewers: Jakob,

Message:
PTAL

Description:
[arm] Decrease the size of the assembler class by allocating buffers of pending 
constants on the heap.

BUG=chromium:521828
LOG=N

Please review this at https://codereview.chromium.org/1309903009/

Base URL: https://chromium.googlesource.com/v8/v8.git@master

Affected files (+33, -2 lines):
  M src/arm/assembler-arm.h
  M src/arm/assembler-arm.cc
  M src/ic/access-compiler.h


Index: src/arm/assembler-arm.cc
diff --git a/src/arm/assembler-arm.cc b/src/arm/assembler-arm.cc
index 633b5d12c076b46e04343c9f2612928b21e46fd8..ca53ca3c0c54a52380816eb7ced5b1febbee6121 100644 
--- a/src/arm/assembler-arm.cc
+++ b/src/arm/assembler-arm.cc
@@ -448,6 +448,8 @@ const Instr kLdrStrInstrTypeMask = 0xffff0000;
 Assembler::Assembler(Isolate* isolate, void* buffer, int buffer_size)
     : AssemblerBase(isolate, buffer, buffer_size),
       recorded_ast_id_(TypeFeedbackId::None()),
+      pending_32_bit_constants_(&pending_32_bit_constants_buffer_[0]),
+      pending_64_bit_constants_(&pending_64_bit_constants_buffer_[0]),
       constant_pool_builder_(kLdrMaxReachBits, kVldrMaxReachBits),
       positions_recorder_(this) {
   reloc_info_writer.Reposition(buffer_ + buffer_size_, pc_);
@@ -465,6 +467,12 @@ Assembler::Assembler(Isolate* isolate, void* buffer, int buffer_size) 

 Assembler::~Assembler() {
   DCHECK(const_pool_blocked_nesting_ == 0);
+  if (pending_32_bit_constants_ != &pending_32_bit_constants_buffer_[0]) {
+    delete[] pending_32_bit_constants_;
+  }
+  if (pending_64_bit_constants_ != &pending_64_bit_constants_buffer_[0]) {
+    delete[] pending_64_bit_constants_;
+  }
 }
@@ -3664,6 +3672,15 @@ ConstantPoolEntry::Access Assembler::ConstantPoolAddEntry(int position, 
     DCHECK(num_pending_32_bit_constants_ < kMaxNumPending32Constants);
     if (num_pending_32_bit_constants_ == 0) {
       first_const_pool_32_use_ = position;
+    } else if (num_pending_32_bit_constants_ == kMinNumPendingConstants &&
+               pending_32_bit_constants_ ==
+                   &pending_32_bit_constants_buffer_[0]) {
+      // Inline buffer is over, switch to dynamically allocated buffer.
+      pending_32_bit_constants_ =
+          new ConstantPoolEntry[kMaxNumPending32Constants];
+      std::copy(&pending_32_bit_constants_buffer_[0],
+                &pending_32_bit_constants_buffer_[kMinNumPendingConstants],
+                &pending_32_bit_constants_[0]);
     }
     ConstantPoolEntry entry(position, value, sharing_ok);
     pending_32_bit_constants_[num_pending_32_bit_constants_++] = entry;
@@ -3684,6 +3701,15 @@ ConstantPoolEntry::Access Assembler::ConstantPoolAddEntry(int position, 
     DCHECK(num_pending_64_bit_constants_ < kMaxNumPending64Constants);
     if (num_pending_64_bit_constants_ == 0) {
       first_const_pool_64_use_ = position;
+    } else if (num_pending_64_bit_constants_ == kMinNumPendingConstants &&
+               pending_64_bit_constants_ ==
+                   &pending_64_bit_constants_buffer_[0]) {
+      // Inline buffer is over, switch to dynamically allocated buffer.
+      pending_64_bit_constants_ =
+          new ConstantPoolEntry[kMaxNumPending64Constants];
+      std::copy(&pending_64_bit_constants_buffer_[0],
+                &pending_64_bit_constants_buffer_[kMinNumPendingConstants],
+                &pending_64_bit_constants_[0]);
     }
     ConstantPoolEntry entry(position, value);
     pending_64_bit_constants_[num_pending_64_bit_constants_++] = entry;
Index: src/arm/assembler-arm.h
diff --git a/src/arm/assembler-arm.h b/src/arm/assembler-arm.h
index d0fcac206e0b7916995c3c9cf09482769273ea91..c54e51df78cb57c146f1f9f815214ca899057e49 100644 
--- a/src/arm/assembler-arm.h
+++ b/src/arm/assembler-arm.h
@@ -1465,6 +1465,7 @@ class Assembler : public AssemblerBase {
   static const int kMaxDistToIntPool = 4*KB;
   static const int kMaxDistToFPPool = 1*KB;
   // All relocations could be integer, it therefore acts as the limit.
+  static const int kMinNumPendingConstants = 4;
static const int kMaxNumPending32Constants = kMaxDistToIntPool / kInstrSize; static const int kMaxNumPending64Constants = kMaxDistToFPPool / kInstrSize; 

@@ -1598,8 +1599,10 @@ class Assembler : public AssemblerBase {
   // pending relocation entry per instruction.

   // The buffers of pending constant pool entries.
-  ConstantPoolEntry pending_32_bit_constants_[kMaxNumPending32Constants];
-  ConstantPoolEntry pending_64_bit_constants_[kMaxNumPending64Constants];
+ ConstantPoolEntry pending_32_bit_constants_buffer_[kMinNumPendingConstants]; + ConstantPoolEntry pending_64_bit_constants_buffer_[kMinNumPendingConstants]; 
+  ConstantPoolEntry* pending_32_bit_constants_;
+  ConstantPoolEntry* pending_64_bit_constants_;
   // Number of pending constant pool entries in the 32 bits buffer.
   int num_pending_32_bit_constants_;
   // Number of pending constant pool entries in the 64 bits buffer.
Index: src/ic/access-compiler.h
diff --git a/src/ic/access-compiler.h b/src/ic/access-compiler.h
index 61567a2224b14132e57a1bdd90f143a595d01f17..75503c090acbe4a0e5d4f1b8ca7352605744bbea 100644 
--- a/src/ic/access-compiler.h
+++ b/src/ic/access-compiler.h
@@ -81,6 +81,8 @@ class PropertyAccessCompiler BASE_EMBEDDED {

   Isolate* isolate_;
   MacroAssembler masm_;
+  // Ensure that MacroAssembler is reasonably big.
+  STATIC_ASSERT(sizeof(MacroAssembler) < KB / 2);
 };
 }
 }  // namespace v8::internal


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