[llvm-commits] CVS: llvm/lib/Bitcode/Writer/BitcodeWriter.cpp

[Chris Lattner]

Changes in directory llvm/lib/Bitcode/Writer:

BitcodeWriter.cpp updated: 1.35 -> 1.36
---
Log message:

Implement support for globally associating abbrevs with block IDs, which
relieves us from having to emit the abbrevs into each instance of the block.
This shrinks kc.bit from 3368K to 3333K, but will be a more significant win
once instructions are abbreviated.

The VST went from:

  Block ID #14 (VALUE_SYMTAB):
      Num Instances: 2345
         Total Size: 1.29508e+07b/1.61885e+06B/404713W
       Average Size: 5522.73b/690.342B/172.585W
          % of file: 48.0645
  Tot/Avg SubBlocks: 0/0
    Tot/Avg Abbrevs: 7035/3
    Tot/Avg Records: 120924/51.5667
      % Abbrev Recs: 100

to:

  Block ID #14 (VALUE_SYMTAB):
      Num Instances: 2345
         Total Size: 1.26713e+07b/1.58391e+06B/395978W
       Average Size: 5403.53b/675.442B/168.86W
          % of file: 47.5198
  Tot/Avg SubBlocks: 0/0
    Tot/Avg Abbrevs: 0/0
    Tot/Avg Records: 120924/51.5667
      % Abbrev Recs: 100

because we didn't emit the same 3 abbrevs 2345 times :)



---
Diffs of the changes:  (+33 -42)

 BitcodeWriter.cpp |   75 +++++++++++++++++++++++-------------------------------
 1 files changed, 33 insertions(+), 42 deletions(-)


Index: llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
diff -u llvm/lib/Bitcode/Writer/BitcodeWriter.cpp:1.35 llvm/lib/Bitcode/Writer/BitcodeWriter.cpp:1.36
--- llvm/lib/Bitcode/Writer/BitcodeWriter.cpp:1.35	Fri May  4 16:31:13 2007
+++ llvm/lib/Bitcode/Writer/BitcodeWriter.cpp	Fri May  4 19:17:00 2007
@@ -714,36 +714,6 @@
   if (VST.empty()) return;
   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 3);
 
-  { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
-    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
-    if (Stream.EmitAbbrev(Abbv) != VST_ENTRY_8_ABBREV)
-      assert(0 && "Unexpected abbrev ordering!");
-  }
-  
-  { // 7-bit fixed width VST_ENTRY strings.
-    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
-    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
-    if (Stream.EmitAbbrev(Abbv) != VST_ENTRY_7_ABBREV)
-      assert(0 && "Unexpected abbrev ordering!");
-  }
-  { // 7-bit fixed width VST_BBENTRY strings.
-    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
-    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
-    if (Stream.EmitAbbrev(Abbv) != VST_BBENTRY_7_ABBREV)
-      assert(0 && "Unexpected abbrev ordering!");
-  }
-  
-  
   // FIXME: Set up the abbrev, we know how many values there are!
   // FIXME: We know if the type names can use 7-bit ascii.
   SmallVector<unsigned, 64> NameVals;
@@ -909,19 +879,40 @@
   // We only want to emit block info records for blocks that have multiple
   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.  Other
   // blocks can defined their abbrevs inline.
-  Stream.EnterSubblock(bitc::BLOCKINFO_BLOCK_ID, 2);
-
-#if 0
-  // Configure TYPE_SYMTAB_BLOCK's.
-
-  // Add an abbrev for VST_ENTRY where the characters each fit in 7 bits.
-  BitCodeAbbrev *Abbv = new BitCodeAbbrev();
-  Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
-  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8); // Value ID
-  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); // Linkage.
+  Stream.EnterBlockInfoBlock(2);
+  
+  { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
+    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, 
+                                   Abbv) != VST_ENTRY_8_ABBREV)
+      assert(0 && "Unexpected abbrev ordering!");
+  }
+  
+  { // 7-bit fixed width VST_ENTRY strings.
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
+    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
+                                   Abbv) != VST_ENTRY_7_ABBREV)
+      assert(0 && "Unexpected abbrev ordering!");
+  }
+  { // 7-bit fixed width VST_BBENTRY strings.
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
+    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
+                                   Abbv) != VST_BBENTRY_7_ABBREV)
+      assert(0 && "Unexpected abbrev ordering!");
+  }
   
-  xxx = Stream.EmitAbbrev(Abbv);
-#endif
   Stream.ExitBlock();
 }