perf symbol: C++ demangling

[acme@doppio ~]$ perf report -s comm,dso,symbol -C firefox -d /usr/lib64/xulrunner-1.9.1/libxul.so | grep :: | head
     2.21%  [.] nsDeque::Push(void*)
     1.78%  [.] GraphWalker::DoWalk(nsDeque&)
     1.30%  [.] GCGraphBuilder::AddNode(void*, nsCycleCollectionParticipant*)
     1.27%  [.] XPCWrappedNative::CallMethod(XPCCallContext&, XPCWrappedNative::CallMode)
     1.18%  [.] imgContainer::DrawFrameTo(gfxIImageFrame*, gfxIImageFrame*, nsRect&)
     1.13%  [.] nsDeque::PopFront()
     1.11%  [.] nsGlobalWindow::RunTimeout(nsTimeout*)
     0.97%  [.] nsXPConnect::Traverse(void*, nsCycleCollectionTraversalCallback&)
     0.95%  [.] nsJSEventListener::cycleCollection::Traverse(void*, nsCycleCollectionTraversalCallback&)
     0.95%  [.] nsCOMPtr_base::~nsCOMPtr_base()
[acme@doppio ~]$

Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Suggested-by: Clark Williams <williams@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090720171412.GB10410@ghostprotocols.net>

tools/perf/Makefile

@@ -345,7 +345,7 @@ BUILTIN_OBJS += builtin-stat.o
 BUILTIN_OBJS += builtin-top.o
 
 PERFLIBS = $(LIB_FILE)
-EXTLIBS =
+EXTLIBS = -lbfd
 
 #
 # Platform specific tweaks

tools/perf/util/symbol.c

@@ -6,9 +6,15 @@
 #include <libelf.h>
 #include <gelf.h>
 #include <elf.h>
+#include <bfd.h>
 
 const char *sym_hist_filter;
 
+#ifndef DMGL_PARAMS
+#define DMGL_PARAMS      (1 << 0)       /* Include function args */
+#define DMGL_ANSI        (1 << 1)       /* Include const, volatile, etc */
+#endif
+
 static struct symbol *symbol__new(u64 start, u64 len,
 				  const char *name, unsigned int priv_size,
 				  u64 obj_start, int verbose)
@@ -571,6 +577,8 @@ static int dso__load_sym(struct dso *self, int fd, const char *name,
 						     NULL) != NULL);
 	elf_symtab__for_each_symbol(syms, nr_syms, index, sym) {
 		struct symbol *f;
+		const char *name;
+		char *demangled;
 		u64 obj_start;
 		struct section *section = NULL;
 		int is_label = elf_sym__is_label(&sym);
@@ -609,10 +617,19 @@ static int dso__load_sym(struct dso *self, int fd, const char *name,
 				goto out_elf_end;
 			}
 		}
+		/*
+		 * We need to figure out if the object was created from C++ sources
+		 * DWARF DW_compile_unit has this, but we don't always have access
+		 * to it...
+		 */
+		name = elf_sym__name(&sym, symstrs);
+		demangled = bfd_demangle(NULL, name, DMGL_PARAMS | DMGL_ANSI);
+		if (demangled != NULL)
+			name = demangled;
 
-		f = symbol__new(sym.st_value, sym.st_size,
-				elf_sym__name(&sym, symstrs),
+		f = symbol__new(sym.st_value, sym.st_size, name,
 				self->sym_priv_size, obj_start, verbose);
+		free(demangled);
 		if (!f)
 			goto out_elf_end;