This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG6951b72334bb: [clang] Speedup line offset mapping
computation (authored by serge-sans-paille).
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D99409/new/
https://reviews.llvm.org/D99409
Files:
clang/lib/Basic/SourceManager.cpp
llvm/test/tools/llvm-objdump/X86/source-interleave-prefix.test
Index: llvm/test/tools/llvm-objdump/X86/source-interleave-prefix.test
===================================================================
--- llvm/test/tools/llvm-objdump/X86/source-interleave-prefix.test
+++ llvm/test/tools/llvm-objdump/X86/source-interleave-prefix.test
@@ -11,7 +11,7 @@
; RUN: sed -e "s,SRC_COMPDIR,./Inputs,g" %p/Inputs/source-interleave.ll > %t-relative-path.ll
; RUN: llc -o %t-relative-path.o -filetype=obj -mtriple=x86_64-pc-linux %t-relative-path.ll
-; RUN: llvm-objdump --prefix myprefix --source %t-relative-path.o 2>&1 | \
+; RUN: mkdir -p %t0 && cd %t0 && llvm-objdump --prefix myprefix --source %t-relative-path.o 2>&1 | \
; RUN: FileCheck %s --check-prefix=CHECK-BROKEN-PREFIX -DFILE=%t-relative-path.o -DPREFIX=. -DCOMPDIR=/Inputs
; CHECK-BROKEN-PREFIX: warning: '[[FILE]]': failed to find source [[PREFIX]][[COMPDIR]]{{[/\\]}}source-interleave-x86_64.c
Index: clang/lib/Basic/SourceManager.cpp
===================================================================
--- clang/lib/Basic/SourceManager.cpp
+++ clang/lib/Basic/SourceManager.cpp
@@ -1252,12 +1252,21 @@
return PLoc.getColumn();
}
-#ifdef __SSE2__
-#include <emmintrin.h>
-#endif
+// Check if mutli-byte word x has bytes between m and n, included. This may also
+// catch bytes equal to n + 1.
+// The returned value holds a 0x80 at each byte position that holds a match.
+// see http://graphics.stanford.edu/~seander/bithacks.html#HasBetweenInWord
+template <class T>
+static constexpr inline T likelyhasbetween(T x, unsigned char m,
+ unsigned char n) {
+ return ((x - ~0UL / 255 * (n + 1)) & ~x &
+ (x & ~0UL / 255 * 127) + ~0UL / 255 * (127 - (m - 1))) &
+ ~0UL / 255 * 128;
+}
LineOffsetMapping LineOffsetMapping::get(llvm::MemoryBufferRef Buffer,
llvm::BumpPtrAllocator &Alloc) {
+
// Find the file offsets of all of the *physical* source lines. This does
// not look at trigraphs, escaped newlines, or anything else tricky.
SmallVector<unsigned, 256> LineOffsets;
@@ -1268,18 +1277,51 @@
const unsigned char *Buf = (const unsigned char *)Buffer.getBufferStart();
const unsigned char *End = (const unsigned char *)Buffer.getBufferEnd();
const std::size_t BufLen = End - Buf;
+
unsigned I = 0;
- while (I < BufLen) {
- // Use a fast check to catch both newlines
- if (LLVM_UNLIKELY(Buf[I] <= std::max('\n', '\r'))) {
- if (Buf[I] == '\n') {
- LineOffsets.push_back(I + 1);
- } else if (Buf[I] == '\r') {
+ uint64_t Word;
+
+ // scan sizeof(Word) bytes at a time for new lines.
+ // This is much faster than scanning each byte independently.
+ if (BufLen > sizeof(Word)) {
+ do {
+ memcpy(&Word, Buf + I, sizeof(Word));
+ // no new line => jump over sizeof(Word) bytes.
+ auto Mask = likelyhasbetween(Word, '\n', '\r');
+ if (!Mask) {
+ I += sizeof(Word);
+ continue;
+ }
+
+ // At that point, Mask contains 0x80 set at each byte that holds a value
+ // in [\n, \r + 1 [
+
+ // Scan for the next newline - it's very likely there's one.
+ unsigned N =
+ llvm::countTrailingZeros(Mask) - 7; // -7 because 0x80 is the marker
+ Word >>= N;
+ I += N / 8 + 1;
+ unsigned char Byte = Word;
+ if (Byte == '\n') {
+ LineOffsets.push_back(I);
+ } else if (Byte == '\r') {
// If this is \r\n, skip both characters.
- if (I + 1 < BufLen && Buf[I + 1] == '\n')
+ if (Buf[I] == '\n')
++I;
- LineOffsets.push_back(I + 1);
+ LineOffsets.push_back(I);
}
+ } while (I < BufLen - sizeof(Word) - 1);
+ }
+
+ // Handle tail using a regular check.
+ while (I < BufLen) {
+ if (Buf[I] == '\n') {
+ LineOffsets.push_back(I + 1);
+ } else if (Buf[I] == '\r') {
+ // If this is \r\n, skip both characters.
+ if (I + 1 < BufLen && Buf[I + 1] == '\n')
+ ++I;
+ LineOffsets.push_back(I + 1);
}
++I;
}
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