Add malloc/new profiling on linux

src/LinuxMallocProfiling.cpp

+//===- subzero/src/LinuxMallocProfiling.cpp - malloc/new tracing  ---------===//
+//
+//                        The Subzero Code Generator
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief malloc/new/...caller tracing.
+///
+//===----------------------------------------------------------------------===//
+
+#include "LinuxMallocProfiling.h"
+
+#ifdef ALLOW_LINUX_MALLOC_PROFILE

[Jim Stichnoth, 2016/03/17 20:09:06]

I would be happier with a blank line before and after each #ifdef/#else/#endif.

[sehr, 2016/03/17 20:58:21]

Done.

+#include <dlfcn.h>
+#include <malloc.h>
+#include <unordered_map>
+
+extern "C" void *__libc_malloc(size_t size);
+
+namespace {
+// The Callers structure allocates memory, which would perturb the tracing.
+// InAllocatorFunction is true when we are tracing a new/malloc/...
+bool InAllocatorFunction = false;
+
+// Keep track of the number of times a particular call site address invoked
+// an allocator. NOTE: this is not thread safe, so the user must invoke with
+// --threads=0 to enable profiling.
+using MallocMap = std::unordered_map<void *, uint64_t>;
+MallocMap *Callers;
+
+void *internalAllocator(size_t size, void *caller) {
+  if (Callers != nullptr && !InAllocatorFunction) {
+    InAllocatorFunction = true;
+    ++(*Callers)[caller];
+    InAllocatorFunction = false;
+  }
+  return __libc_malloc(size);
+}
+} // end of anonymous namespace
+
+// new, new[], and malloc are all defined as weak symbols to allow them

[Jim Stichnoth, 2016/03/17 20:09:05]

reflow comment to 80-col

[sehr, 2016/03/17 20:58:21]

Done.

+// to be overridden by user code.  This gives us a convenient place to hook
+// allocation tracking, to record the IP of the caller, which we get from the
+// call to __builtin_return_address.
+void *operator new(size_t size) {
+  void *caller = __builtin_return_address(0);
+  return internalAllocator(size, caller);
+}
+
+void *operator new[](size_t size) {
+  void *caller = __builtin_return_address(0);
+  return internalAllocator(size, caller);
+}
+
+extern "C" void *malloc(size_t size) {
+  void *caller = __builtin_return_address(0);
+  return internalAllocator(size, caller);
+}
+
+namespace Ice {
+
+LinuxMallocProfiling::LinuxMallocProfiling(size_t NumThreads, Ostream *Ls)
+    : Ls(Ls) {
+  if (NumThreads != 0) {
+    *Ls << "NOTE: Malloc profiling is not thread safe.  "
+        << "Use --threads=0 to enable.\n";

[Jim Stichnoth, 2016/03/17 20:09:06]

Tiny nit: omit the last "<<" and take advantage of string literal concatenation.

[sehr, 2016/03/17 20:58:21]

Done.

+    return;
+  }
+  Callers = new MallocMap();
+}
+
+LinuxMallocProfiling::~LinuxMallocProfiling() {
+  if (Callers == nullptr) {
+    return;
+  }
+  for (const auto &C : *Callers) {
+    Dl_info dli;
+    dladdr(C.first, &dli);
+
+    *Ls << C.second << " ";
+    if (dli.dli_sname == NULL) {
+      *Ls << C.first;
+    } else {
+      *Ls << dli.dli_sname;
+    }
+    *Ls << "\n";
+  }
+  delete Callers;
+  Callers = nullptr;
+}
+} // end of namespace Ice
+#else  // !ALLOW_LINUX_MALLOC_PROFILE
+namespace Ice {
+
+LinuxMallocProfiling::LinuxMallocProfiling(size_t NumThreads, Ostream *Ls) {
+  (void)NumThreads;
+  (void)Ls;
+}
+
+LinuxMallocProfiling::~LinuxMallocProfiling() {}
+} // end of namespace Ice
+#endif // ALLOW_LINUX_MALLOC_PROFILE