From: Yaron Keren Date: Thu, 13 Aug 2015 06:19:52 +0000 (+0000) Subject: Modify raw_svector_ostream to use its SmallString without additional buffering. X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=d4177b27058cfed2320f3ea1bf7ac2552f5a3e71;p=oota-llvm.git Modify raw_svector_ostream to use its SmallString without additional buffering. This is faster and avoids the stream and SmallString state synchronization issue. resync() is a no-op and may be safely deleted. I'll do so in a follow-up commit. Reviewed by Rafael Espindola. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@244870 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/include/llvm/Support/raw_ostream.h b/include/llvm/Support/raw_ostream.h index c12f90142ab..5000774a6cd 100644 --- a/include/llvm/Support/raw_ostream.h +++ b/include/llvm/Support/raw_ostream.h @@ -485,6 +485,9 @@ public: /// A raw_ostream that writes to an SmallVector or SmallString. This is a /// simple adaptor class. This class does not encounter output errors. +/// raw_svector_ostream operates without a buffer, delegating all memory +/// management to the SmallString. Thus the SmallString is always up-to-date, +/// may be used directly and there is no need to call flush(). class raw_svector_ostream : public raw_pwrite_stream { SmallVectorImpl &OS; @@ -493,31 +496,24 @@ class raw_svector_ostream : public raw_pwrite_stream { void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override; - /// Return the current position within the stream, not counting the bytes - /// currently in the buffer. + /// Return the current position within the stream. uint64_t current_pos() const override; -protected: - // Like the regular constructor, but doesn't call init. - explicit raw_svector_ostream(SmallVectorImpl &O, unsigned); - void init(); - public: /// Construct a new raw_svector_ostream. /// /// \param O The vector to write to; this should generally have at least 128 /// bytes free to avoid any extraneous memory overhead. - explicit raw_svector_ostream(SmallVectorImpl &O); - ~raw_svector_ostream() override; + explicit raw_svector_ostream(SmallVectorImpl &O) : OS(O) { + SetUnbuffered(); + } + ~raw_svector_ostream() override {} - /// This is called when the SmallVector we're appending to is changed outside - /// of the raw_svector_ostream's control. It is only safe to do this if the - /// raw_svector_ostream has previously been flushed. - void resync(); + // FIXME: resync is no-op. Remove it and its users. + void resync() {} - /// Flushes the stream contents to the target vector and return a StringRef - /// for the vector contents. - StringRef str(); + /// Return a StringRef for the vector contents. + StringRef str() { return StringRef(OS.data(), OS.size()); } }; /// A raw_ostream that discards all output. @@ -540,9 +536,7 @@ class buffer_ostream : public raw_svector_ostream { SmallVector Buffer; public: - buffer_ostream(raw_ostream &OS) : raw_svector_ostream(Buffer, 0), OS(OS) { - init(); - } + buffer_ostream(raw_ostream &OS) : raw_svector_ostream(Buffer), OS(OS) {} ~buffer_ostream() { OS << str(); } }; diff --git a/lib/Support/raw_ostream.cpp b/lib/Support/raw_ostream.cpp index 42f830bbf0f..3a37987378a 100644 --- a/lib/Support/raw_ostream.cpp +++ b/lib/Support/raw_ostream.cpp @@ -755,72 +755,15 @@ void raw_string_ostream::write_impl(const char *Ptr, size_t Size) { // raw_svector_ostream //===----------------------------------------------------------------------===// -// The raw_svector_ostream implementation uses the SmallVector itself as the -// buffer for the raw_ostream. We guarantee that the raw_ostream buffer is -// always pointing past the end of the vector, but within the vector -// capacity. This allows raw_ostream to write directly into the correct place, -// and we only need to set the vector size when the data is flushed. +uint64_t raw_svector_ostream::current_pos() const { return OS.size(); } -raw_svector_ostream::raw_svector_ostream(SmallVectorImpl &O, unsigned) - : OS(O) {} - -raw_svector_ostream::raw_svector_ostream(SmallVectorImpl &O) : OS(O) { - init(); -} - -void raw_svector_ostream::init() { - // Set up the initial external buffer. We make sure that the buffer has at - // least 128 bytes free; raw_ostream itself only requires 64, but we want to - // make sure that we don't grow the buffer unnecessarily on destruction (when - // the data is flushed). See the FIXME below. - OS.reserve(OS.size() + 128); - SetBuffer(OS.end(), OS.capacity() - OS.size()); -} - -raw_svector_ostream::~raw_svector_ostream() { - // FIXME: Prevent resizing during this flush(). - flush(); -} +void raw_svector_ostream::write_impl(const char *Ptr, size_t Size) { + OS.append(Ptr, Ptr + Size); +}; void raw_svector_ostream::pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) { - flush(); - memcpy(OS.begin() + Offset, Ptr, Size); -} - -/// resync - This is called when the SmallVector we're appending to is changed -/// outside of the raw_svector_ostream's control. It is only safe to do this -/// if the raw_svector_ostream has previously been flushed. -void raw_svector_ostream::resync() { - assert(GetNumBytesInBuffer() == 0 && "Didn't flush before mutating vector"); - - if (OS.capacity() - OS.size() < 64) - OS.reserve(OS.capacity() * 2); - SetBuffer(OS.end(), OS.capacity() - OS.size()); -} - -void raw_svector_ostream::write_impl(const char *Ptr, size_t Size) { - if (Ptr == OS.end()) { - // Grow the buffer to include the scratch area without copying. - size_t NewSize = OS.size() + Size; - assert(NewSize <= OS.capacity() && "Invalid write_impl() call!"); - OS.set_size(NewSize); - } else { - assert(!GetNumBytesInBuffer()); - OS.append(Ptr, Ptr + Size); - } - - OS.reserve(OS.size() + 64); - SetBuffer(OS.end(), OS.capacity() - OS.size()); -} - -uint64_t raw_svector_ostream::current_pos() const { - return OS.size(); -} - -StringRef raw_svector_ostream::str() { - flush(); - return StringRef(OS.begin(), OS.size()); + memcpy(OS.data() + Offset, Ptr, Size); } //===----------------------------------------------------------------------===//