Changes in directory llvm/lib/Bitcode/Writer:
BitcodeWriter.cpp updated: 1.45 -> 1.46
---
Log message:
add a denser encoding for null terminated strings, add a 6-bit abbrev as
well. This shrinks kc++ from 2724088 to 2717360 bytes.
---
Diffs of the changes: (+36 -8)
BitcodeWriter.cpp | 44 ++++++++++++++++++++++++++++++++++++--------
1 files changed, 36 insertions(+), 8 deletions(-)
Index: llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
diff -u llvm/lib/Bitcode/Writer/BitcodeWriter.cpp:1.45
llvm/lib/Bitcode/Writer/BitcodeWriter.cpp:1.46
--- llvm/lib/Bitcode/Writer/BitcodeWriter.cpp:1.45 Sat May 5 19:42:18 2007
+++ llvm/lib/Bitcode/Writer/BitcodeWriter.cpp Sat May 5 19:53:07 2007
@@ -411,7 +411,9 @@
Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
unsigned AggregateAbbrev = 0;
- unsigned String7Abbrev = 0;
+ unsigned String8Abbrev = 0;
+ unsigned CString7Abbrev = 0;
+ unsigned CString6Abbrev = 0;
// If this is a constant pool for the module, emit module-specific abbrevs.
if (isGlobal) {
// Abbrev for CST_CODE_AGGREGATE.
@@ -425,8 +427,20 @@
Abbv = new BitCodeAbbrev();
Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+ Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
+ String8Abbrev = Stream.EmitAbbrev(Abbv);
+ // Abbrev for CST_CODE_CSTRING.
+ Abbv = new BitCodeAbbrev();
+ Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
+ Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
- String7Abbrev = Stream.EmitAbbrev(Abbv);
+ CString7Abbrev = Stream.EmitAbbrev(Abbv);
+ // Abbrev for CST_CODE_CSTRING.
+ Abbv = new BitCodeAbbrev();
+ Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
+ Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+ Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
+ CString6Abbrev = Stream.EmitAbbrev(Abbv);
}
// FIXME: Install and use abbrevs to reduce size. Install them globally so
@@ -493,15 +507,29 @@
}
} else if (isa<ConstantArray>(C) && cast<ConstantArray>(C)->isString()) {
// Emit constant strings specially.
- Code = bitc::CST_CODE_STRING;
- bool isStr7 = true;
- for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i) {
+ unsigned NumOps = C->getNumOperands();
+ // If this is a null-terminated string, use the denser CSTRING encoding.
+ if (C->getOperand(NumOps-1)->isNullValue()) {
+ Code = bitc::CST_CODE_CSTRING;
+ --NumOps; // Don't encode the null, which isn't allowed by char6.
+ } else {
+ Code = bitc::CST_CODE_STRING;
+ AbbrevToUse = String8Abbrev;
+ }
+ bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
+ bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
+ for (unsigned i = 0; i != NumOps; ++i) {
unsigned char V = cast<ConstantInt>(C->getOperand(i))->getZExtValue();
Record.push_back(V);
- isStr7 &= (V & 128) == 0;
+ isCStr7 &= (V & 128) == 0;
+ if (isCStrChar6)
+ isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
}
- if (isStr7)
- AbbrevToUse = String7Abbrev;
+
+ if (isCStrChar6)
+ AbbrevToUse = CString6Abbrev;
+ else if (isCStr7)
+ AbbrevToUse = CString7Abbrev;
} else if (isa<ConstantArray>(C) || isa<ConstantStruct>(V) ||
isa<ConstantVector>(V)) {
Code = bitc::CST_CODE_AGGREGATE;
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