Profile: set branch weight metadata with data generated from profiling.
This patch implements ProfileDataLoader which loads profile data generated by
-insert-edge-profiling and updates branch weight metadata accordingly.
Patch by Alastair Murray.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162799 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ProfileDataLoader.cpp b/lib/Analysis/ProfileDataLoader.cpp
new file mode 100644
index 0000000..0006492
--- /dev/null
+++ b/lib/Analysis/ProfileDataLoader.cpp
@@ -0,0 +1,186 @@
+//===- ProfileDataLoader.cpp - Load profile information from disk ---------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// The ProfileDataLoader class is used to load raw profiling data from the dump
+// file.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Module.h"
+#include "llvm/InstrTypes.h"
+#include "llvm/Analysis/ProfileDataLoader.h"
+#include "llvm/Analysis/ProfileDataTypes.h"
+#include "llvm/Support/raw_ostream.h"
+#include <cstdio>
+#include <cstdlib>
+using namespace llvm;
+
+namespace llvm {
+
+template<>
+char ProfileDataT<Function,BasicBlock>::ID = 0;
+
+raw_ostream& operator<<(raw_ostream &O, const Function *F) {
+ return O << F->getName();
+}
+
+raw_ostream& operator<<(raw_ostream &O, const BasicBlock *BB) {
+ return O << BB->getName();
+}
+
+raw_ostream& operator<<(raw_ostream &O, std::pair<const BasicBlock *, const BasicBlock *> E) {
+ O << "(";
+
+ if (E.first)
+ O << E.first;
+ else
+ O << "0";
+
+ O << ",";
+
+ if (E.second)
+ O << E.second;
+ else
+ O << "0";
+
+ return O << ")";
+}
+
+} // namespace llvm
+
+/// ByteSwap - Byteswap 'Var' if 'Really' is true. Required when the compiler
+/// host and target have different endianness.
+static inline unsigned ByteSwap(unsigned Var, bool Really) {
+ if (!Really) return Var;
+ return ((Var & (255U<< 0U)) << 24U) |
+ ((Var & (255U<< 8U)) << 8U) |
+ ((Var & (255U<<16U)) >> 8U) |
+ ((Var & (255U<<24U)) >> 24U);
+}
+
+/// AddCounts - Add 'A' and 'B', accounting for the fact that the value of one
+/// (or both) may not be defined.
+static unsigned AddCounts(unsigned A, unsigned B) {
+ // If either value is undefined, use the other.
+ // Undefined + undefined = undefined.
+ if (A == ProfileDataLoader::Uncounted) return B;
+ if (B == ProfileDataLoader::Uncounted) return A;
+
+ // Saturate to the maximum storable value. This could change taken/nottaken
+ // ratios, but is presumably better than wrapping and thus potentially
+ // inverting ratios.
+ unsigned long long tmp = (unsigned long long)A + (unsigned long long)B;
+ if (tmp > (unsigned long long)ProfileDataLoader::MaxCount)
+ tmp = ProfileDataLoader::MaxCount;
+ return (unsigned)tmp;
+}
+
+/// ReadProfilingData - Load 'NumEntries' items of type 'T' from file 'F'
+template <typename T>
+static void ReadProfilingData(const char *ToolName, FILE *F,
+ std::vector<T> &Data, size_t NumEntries) {
+ // Read in the block of data...
+ if (fread(&Data[0], sizeof(T), NumEntries, F) != NumEntries) {
+ errs() << ToolName << ": profiling data truncated!\n";
+ perror(0);
+ exit(1);
+ }
+}
+
+/// ReadProfilingNumEntries - Read how many entries are in this profiling data
+/// packet.
+static unsigned ReadProfilingNumEntries(const char *ToolName, FILE *F,
+ bool ShouldByteSwap) {
+ std::vector<unsigned> NumEntries(1);
+ ReadProfilingData<unsigned>(ToolName, F, NumEntries, 1);
+ return ByteSwap(NumEntries[0], ShouldByteSwap);
+}
+
+/// ReadProfilingBlock - Read the number of entries in the next profiling data
+/// packet and then accumulate the entries into 'Data'.
+static void ReadProfilingBlock(const char *ToolName, FILE *F,
+ bool ShouldByteSwap,
+ std::vector<unsigned> &Data) {
+ // Read the number of entries...
+ unsigned NumEntries = ReadProfilingNumEntries(ToolName, F, ShouldByteSwap);
+
+ // Read in the data.
+ std::vector<unsigned> TempSpace(NumEntries);
+ ReadProfilingData<unsigned>(ToolName, F, TempSpace, (size_t)NumEntries);
+
+ // Make sure we have enough space ...
+ if (Data.size() < NumEntries)
+ Data.resize(NumEntries, ProfileDataLoader::Uncounted);
+
+ // Accumulate the data we just read into the existing data.
+ for (unsigned i = 0; i < NumEntries; ++i) {
+ Data[i] = AddCounts(ByteSwap(TempSpace[i], ShouldByteSwap), Data[i]);
+ }
+}
+
+/// ReadProfilingArgBlock - Read the command line arguments that the progam was
+/// run with when the current profiling data packet(s) were generated.
+static void ReadProfilingArgBlock(const char *ToolName, FILE *F,
+ bool ShouldByteSwap,
+ std::vector<std::string> &CommandLines) {
+ // Read the number of bytes ...
+ unsigned ArgLength = ReadProfilingNumEntries(ToolName, F, ShouldByteSwap);
+
+ // Read in the arguments (if there are any to read). Round up the length to
+ // the nearest 4-byte multiple.
+ std::vector<char> Args(ArgLength+4);
+ if (ArgLength)
+ ReadProfilingData<char>(ToolName, F, Args, (ArgLength+3) & ~3);
+
+ // Store the arguments.
+ CommandLines.push_back(std::string(&Args[0], &Args[ArgLength]));
+}
+
+const unsigned ProfileDataLoader::Uncounted = ~0U;
+const unsigned ProfileDataLoader::MaxCount = ~0U - 1U;
+
+/// ProfileDataLoader ctor - Read the specified profiling data file, exiting
+/// the program if the file is invalid or broken.
+ProfileDataLoader::ProfileDataLoader(const char *ToolName,
+ const std::string &Filename)
+ : Filename(Filename) {
+ FILE *F = fopen(Filename.c_str(), "rb");
+ if (F == 0) {
+ errs() << ToolName << ": Error opening '" << Filename << "': ";
+ perror(0);
+ exit(1);
+ }
+
+ // Keep reading packets until we run out of them.
+ unsigned PacketType;
+ while (fread(&PacketType, sizeof(unsigned), 1, F) == 1) {
+ // If the low eight bits of the packet are zero, we must be dealing with an
+ // endianness mismatch. Byteswap all words read from the profiling
+ // information. This can happen when the compiler host and target have
+ // different endianness.
+ bool ShouldByteSwap = (char)PacketType == 0;
+ PacketType = ByteSwap(PacketType, ShouldByteSwap);
+
+ switch (PacketType) {
+ case ArgumentInfo:
+ ReadProfilingArgBlock(ToolName, F, ShouldByteSwap, CommandLines);
+ break;
+
+ case EdgeInfo:
+ ReadProfilingBlock(ToolName, F, ShouldByteSwap, EdgeCounts);
+ break;
+
+ default:
+ errs() << ToolName << ": Unknown packet type #" << PacketType << "!\n";
+ exit(1);
+ }
+ }
+
+ fclose(F);
+}