[cfe-commits] r38669 - /cfe/cfe/trunk/Driver/PrintPreprocessedOutput.cpp
sabre at cs.uiuc.edu
sabre at cs.uiuc.edu
Wed Jul 11 09:23:40 PDT 2007
Author: sabre
Date: Wed Jul 11 11:23:40 2007
New Revision: 38669
URL: http://llvm.org/viewvc/llvm-project?rev=38669&view=rev
Log:
Switch to using unix "write" when available, instead of stdio. This speeds up
-E -P mode by 10% (i.e. takes away almost all i/o time).
Modified:
cfe/cfe/trunk/Driver/PrintPreprocessedOutput.cpp
Modified: cfe/cfe/trunk/Driver/PrintPreprocessedOutput.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/cfe/trunk/Driver/PrintPreprocessedOutput.cpp?rev=38669&r1=38668&r2=38669&view=diff
==============================================================================
--- cfe/cfe/trunk/Driver/PrintPreprocessedOutput.cpp (original)
+++ cfe/cfe/trunk/Driver/PrintPreprocessedOutput.cpp Wed Jul 11 11:23:40 2007
@@ -17,11 +17,86 @@
#include "clang/Lex/Pragma.h"
#include "clang/Basic/SourceManager.h"
#include "llvm/Support/CommandLine.h"
-// NOTE: we use stdio because it is empirically much faster than iostreams.
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Config/config.h"
#include <cstdio>
using namespace llvm;
using namespace clang;
+//===----------------------------------------------------------------------===//
+// Simple buffered I/O
+//===----------------------------------------------------------------------===//
+//
+// Empirically, iostream is over 30% slower than stdio for this workload, and
+// stdio itself isn't very well suited. The problem with stdio is use of
+// putchar_unlocked. We have many newline characters that need to be emitted,
+// but stdio needs to do extra checks to handle line buffering mode. These
+// extra checks make putchar_unlocked fall off its inlined code path, hitting
+// slow system code. In practice, using 'write' directly makes 'clang -E -P'
+// about 10% faster than using the stdio path on darwin.
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#else
+#define USE_STDIO 1
+#endif
+
+static char *OutBufStart = 0, *OutBufEnd, *OutBufCur;
+
+/// InitOutputBuffer - Initialize our output buffer.
+///
+static void InitOutputBuffer() {
+#ifndef USE_STDIO
+ OutBufStart = new char[64*1024];
+ OutBufEnd = OutBufStart+64*1024;
+ OutBufCur = OutBufStart;
+#endif
+}
+
+/// FlushBuffer - Write the accumulated bytes to the output stream.
+///
+static void FlushBuffer() {
+#ifndef USE_STDIO
+ write(STDOUT_FILENO, OutBufStart, OutBufCur-OutBufStart);
+ OutBufCur = OutBufStart;
+#endif
+}
+
+/// CleanupOutputBuffer - Finish up output.
+///
+static void CleanupOutputBuffer() {
+#ifndef USE_STDIO
+ FlushBuffer();
+ delete [] OutBufStart;
+#endif
+}
+
+static void OutputChar(char c) {
+#ifdef USE_STDIO
+ putchar_unlocked(c);
+#else
+ if (OutBufCur >= OutBufEnd)
+ FlushBuffer();
+ *OutBufCur++ = c;
+#endif
+}
+
+static void OutputString(const char *Ptr, unsigned Size) {
+#ifdef USE_STDIO
+ fwrite(Ptr, Size, 1, stdout);
+#else
+ if (OutBufCur+Size >= OutBufEnd)
+ FlushBuffer();
+ memcpy(OutBufCur, Ptr, Size);
+ OutBufCur += Size;
+#endif
+}
+
+
+//===----------------------------------------------------------------------===//
+// Preprocessed token printer
+//===----------------------------------------------------------------------===//
+
static cl::opt<bool>
DisableLineMarkers("P", cl::desc("Disable linemarker output in -E mode"));
@@ -31,13 +106,17 @@
static bool EmodeEmittedTokensOnThisLine;
static DirectoryLookup::DirType EmodeFileType =DirectoryLookup::NormalHeaderDir;
-
-
/// MoveToLine - Move the output to the source line specified by the location
/// object. We can do this by emitting some number of \n's, or be emitting a
/// #line directive.
static void MoveToLine(SourceLocation Loc) {
- if (DisableLineMarkers) return;
+ if (DisableLineMarkers) {
+ if (EmodeEmittedTokensOnThisLine) {
+ OutputChar('\n');
+ EmodeEmittedTokensOnThisLine = false;
+ }
+ return;
+ }
unsigned LineNo = EModePP->getSourceManager().getLineNumber(Loc);
@@ -46,24 +125,28 @@
if (LineNo-EModeCurLine < 8) {
unsigned CurLine = EModeCurLine;
for (; CurLine != LineNo; ++CurLine)
- putchar_unlocked('\n');
+ OutputChar('\n');
EModeCurLine = CurLine;
} else {
if (EmodeEmittedTokensOnThisLine) {
- putchar_unlocked('\n');
+ OutputChar('\n');
EmodeEmittedTokensOnThisLine = false;
}
EModeCurLine = LineNo;
- if (DisableLineMarkers) return;
- printf("# %d %s", LineNo, EModeCurFilename.c_str());
+ OutputChar('#');
+ OutputChar(' ');
+ std::string Num = utostr_32(LineNo);
+ OutputString(&Num[0], Num.size());
+ OutputChar(' ');
+ OutputString(&EModeCurFilename[0], EModeCurFilename.size());
if (EmodeFileType == DirectoryLookup::SystemHeaderDir)
- printf(" 3");
+ OutputString(" 3", 2);
else if (EmodeFileType == DirectoryLookup::ExternCSystemHeaderDir)
- printf(" 3 4");
- putchar_unlocked('\n');
+ OutputString(" 3 4", 4);
+ OutputChar('\n');
}
}
@@ -92,30 +175,36 @@
EmodeFileType = FileType;
if (EmodeEmittedTokensOnThisLine) {
- putchar_unlocked('\n');
+ OutputChar('\n');
EmodeEmittedTokensOnThisLine = false;
}
if (DisableLineMarkers) return;
- printf("# %d %s", EModeCurLine, EModeCurFilename.c_str());
+ OutputChar('#');
+ OutputChar(' ');
+ std::string Num = utostr_32(EModeCurLine);
+ OutputString(&Num[0], Num.size());
+ OutputChar(' ');
+ OutputString(&EModeCurFilename[0], EModeCurFilename.size());
+
switch (Reason) {
case Preprocessor::EnterFile:
- printf(" 1");
+ OutputString(" 1", 2);
break;
case Preprocessor::ExitFile:
- printf(" 2");
+ OutputString(" 2", 2);
break;
case Preprocessor::SystemHeaderPragma: break;
case Preprocessor::RenameFile: break;
}
if (FileType == DirectoryLookup::SystemHeaderDir)
- printf(" 3");
+ OutputString(" 3", 2);
else if (FileType == DirectoryLookup::ExternCSystemHeaderDir)
- printf(" 3 4");
+ OutputString(" 3 4", 4);
- putchar_unlocked('\n');
+ OutputChar('\n');
}
/// HandleIdent - Handle #ident directives when read by the preprocessor.
@@ -123,7 +212,8 @@
static void HandleIdent(SourceLocation Loc, const std::string &Val) {
MoveToLine(Loc);
- printf("#ident %s", Val.c_str());
+ OutputString("#ident ", strlen("#ident "));
+ OutputString(&Val[0], Val.size());
EmodeEmittedTokensOnThisLine = true;
}
@@ -146,11 +236,11 @@
// is not handled as a #define next time through the preprocessor if in
// -fpreprocessed mode.
if (ColNo <= 1 && Tok.getKind() == tok::hash)
- putchar_unlocked(' ');
+ OutputChar(' ');
// Otherwise, indent the appropriate number of spaces.
for (; ColNo > 1; --ColNo)
- putchar_unlocked(' ');
+ OutputChar(' ');
}
namespace {
@@ -161,16 +251,17 @@
// Figure out what line we went to and insert the appropriate number of
// newline characters.
MoveToLine(PragmaTok.getLocation());
- printf(Prefix);
+ OutputString(Prefix, strlen(Prefix));
// Read and print all of the pragma tokens.
while (PragmaTok.getKind() != tok::eom) {
if (PragmaTok.hasLeadingSpace())
- putchar_unlocked(' ');
- printf("%s", PP.getSpelling(PragmaTok).c_str());
+ OutputChar(' ');
+ std::string TokSpell = PP.getSpelling(PragmaTok);
+ OutputString(&TokSpell[0], TokSpell.size());
PP.LexUnexpandedToken(PragmaTok);
}
- putchar_unlocked('\n');
+ OutputChar('\n');
}
};
} // end anonymous namespace
@@ -178,6 +269,8 @@
/// DoPrintPreprocessedInput - This implements -E mode.
///
void clang::DoPrintPreprocessedInput(Preprocessor &PP) {
+ InitOutputBuffer();
+
LexerToken Tok;
char Buffer[256];
EModeCurLine = 0;
@@ -200,19 +293,21 @@
if (Tok.isAtStartOfLine()) {
HandleFirstTokOnLine(Tok, PP);
} else if (Tok.hasLeadingSpace()) {
- putchar_unlocked(' ');
+ OutputChar(' ');
}
if (Tok.getLength() < 256) {
unsigned Len = PP.getSpelling(Tok, Buffer);
Buffer[Len] = 0;
- fwrite(Buffer, Len, 1, stdout);
+ OutputString(Buffer, Len);
} else {
std::string S = PP.getSpelling(Tok);
- fwrite(&S[0], S.size(), 1, stdout);
+ OutputString(&S[0], S.size());
}
EmodeEmittedTokensOnThisLine = true;
} while (Tok.getKind() != tok::eof);
- putchar_unlocked('\n');
+ OutputChar('\n');
+
+ CleanupOutputBuffer();
}
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