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Fix a heinous inefficiency introduced in r149918, wherein reading eac…

…h byte of a

BLOB (i.e., large, performance intensive data) in a bitcode file was switched to
invoking one virtual method call per byte read.  Now we do one virtual call per
BLOB.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173065 91177308-0d34-0410-b5e6-96231b3b80d8
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commit 69582cf6c46456ad542df5aa09c47700c9525645 1 parent afe77f3
Chris Lattner authored
6 include/llvm/Bitcode/BitstreamReader.h
View
@@ -237,12 +237,6 @@ class BitstreamCursor {
static_cast<uint64_t>(pos - 1));
}
- unsigned char getByte(size_t pos) {
- uint8_t byte = -1;
- BitStream->getBitcodeBytes().readByte(pos, &byte);
- return byte;
- }
-
uint32_t getWord(size_t pos) {
uint8_t buf[4] = { 0xFF, 0xFF, 0xFF, 0xFF };
BitStream->getBitcodeBytes().readBytes(pos, sizeof(buf), buf, NULL);
17 lib/Bitcode/Reader/BitstreamReader.cpp
View
@@ -255,18 +255,17 @@ unsigned BitstreamCursor::readRecord(unsigned AbbrevID,
break;
}
- // Otherwise, read the number of bytes. If we can return a reference to
- // the data, do so to avoid copying it.
+ // Otherwise, inform the streamer that we need these bytes in memory.
+ const char *Ptr = (const char*)
+ BitStream->getBitcodeBytes().getPointer(CurBitPos/8, NumElts);
+
+ // If we can return a reference to the data, do so to avoid copying it.
if (Blob) {
- *Blob =
- StringRef((const char*)BitStream->getBitcodeBytes().getPointer(
- CurBitPos/8, NumElts),
- NumElts);
+ *Blob = StringRef(Ptr, NumElts);
} else {
- // FIXME: This is a brutally inefficient way to do this. Why isn't this
- // just using getPointer?
+ // Otherwise, unpack into Vals with zero extension.
for (; NumElts; --NumElts)
- Vals.push_back(Read(8));
+ Vals.push_back((unsigned char)*Ptr++);
}
// Skip over tail padding.
JumpToBit(NewEnd);
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