libgo: Implement and use runtime.Caller, runtime.Func.FileLine.

From-SVN: r185025

5 files changed, 130 insertions, 39 deletions

diff --git a/libgo/runtime/go-caller.c b/libgo/runtime/go-caller.c
index b18759f..f2bebeb 100644
--- a/libgo/runtime/go-caller.c
+++ b/libgo/runtime/go-caller.c
@@ -8,8 +8,64 @@
 
 #include <stdint.h>
 
+#include "runtime.h"
 #include "go-string.h"
 
+/* Get the function name, file name, and line number for a PC value.
+   We use the DWARF debug information to get this.  Rather than write
+   a whole new library in C, we use the existing Go library.
+   Unfortunately, the Go library is only available if the debug/elf
+   package is imported (we use debug/elf for both ELF and Mach-O, in
+   this case).  We arrange for the debug/elf package to register
+   itself, and tweak the various packages that need this information
+   to import debug/elf where possible.  */
+
+/* The function that returns function/file/line information.  */
+
+typedef _Bool (*infofn_type) (uintptr_t, struct __go_string *,
+			      struct __go_string *, int *);
+static infofn_type infofn;
+
+/* The function that returns the value of a symbol, used to get the
+   entry address of a function.  */
+
+typedef _Bool (*symvalfn_type) (struct __go_string, uintptr_t *);
+static symvalfn_type symvalfn;
+
+/* This is called by debug/elf to register the function that returns
+   function/file/line information.  */
+
+void RegisterDebugLookup (infofn_type, symvalfn_type)
+  __asm__ ("libgo_runtime.runtime.RegisterDebugLookup");
+
+void
+RegisterDebugLookup (infofn_type pi, symvalfn_type ps)
+{
+  infofn = pi;
+  symvalfn = ps;
+}
+
+/* Return function/file/line information for PC.  */
+
+_Bool
+__go_file_line (uintptr_t pc, struct __go_string *fn, struct __go_string *file,
+		int *line)
+{
+  if (infofn == NULL)
+    return 0;
+  return infofn (pc, fn, file, line);
+}
+
+/* Return the value of a symbol.  */
+
+_Bool
+__go_symbol_value (struct __go_string sym, uintptr_t *val)
+{
+  if (symvalfn == NULL)
+    return 0;
+  return symvalfn (sym, val);
+}
+
 /* The values returned by runtime.Caller.  */
 
 struct caller_ret
@@ -20,32 +76,71 @@ struct caller_ret
   _Bool ok;
 };
 
-/* Implement runtime.Caller.  */
-
 struct caller_ret Caller (int n) asm ("libgo_runtime.runtime.Caller");
 
+Func *FuncForPC (uintptr_t) asm ("libgo_runtime.runtime.FuncForPC");
+
+/* Implement runtime.Caller.  */
+
 struct caller_ret
-Caller (int n __attribute__ ((unused)))
+Caller (int skip)
 {
   struct caller_ret ret;
+  uintptr pc;
+  int32 n;
+  struct __go_string fn;
 
-  /* A proper implementation needs to dig through the debugging
-     information.  */
-  ret.pc = (uint64_t) (uintptr_t) __builtin_return_address (0);
-  ret.file.__data = NULL;
-  ret.file.__length = 0;
-  ret.line = 0;
-  ret.ok = 0;
-
+  runtime_memclr (&ret, sizeof ret);
+  n = runtime_callers (skip + 1, &pc, 1);
+  if (n < 1)
+    return ret;
+  ret.pc = pc;
+  ret.ok = __go_file_line (pc, &fn, &ret.file, &ret.line);
   return ret;
 }
 
 /* Implement runtime.FuncForPC.  */
 
-void *FuncForPC (uintptr_t) asm ("libgo_runtime.runtime.FuncForPC");
+Func *
+FuncForPC (uintptr_t pc)
+{
+  Func *ret;
+  struct __go_string fn;
+  struct __go_string file;
+  int line;
+  uintptr_t val;
 
-void *
-FuncForPC(uintptr_t pc __attribute__ ((unused)))
+  if (!__go_file_line (pc, &fn, &file, &line))
+    return NULL;
+  if (!__go_symbol_value (fn, &val))
+    return NULL;
+
+  ret = (Func *) runtime_malloc (sizeof (*ret));
+  ret->name = fn;
+  ret->entry = val;
+  return ret;
+}
+
+/* Look up the file and line information for a PC within a
+   function.  */
+
+struct funcline_go_return
 {
-  return NULL;
+  struct __go_string retfile;
+  int retline;
+};
+
+struct funcline_go_return
+runtime_funcline_go (Func *f, uintptr targetpc)
+  __asm__ ("libgo_runtime.runtime.funcline_go");
+
+struct funcline_go_return
+runtime_funcline_go (Func *f __attribute__((unused)), uintptr targetpc)
+{
+  struct funcline_go_return ret;
+  struct __go_string fn;
+
+  if (!__go_file_line (targetpc, &fn, &ret.retfile,  &ret.retline))
+    runtime_memclr (&ret, sizeof ret);
+  return ret;
 }
diff --git a/libgo/runtime/go-callers.c b/libgo/runtime/go-callers.c
index 0089c67..09556c3 100644
--- a/libgo/runtime/go-callers.c
+++ b/libgo/runtime/go-callers.c
@@ -25,8 +25,13 @@ backtrace (struct _Unwind_Context *context, void *varg)
 {
   struct callers_data *arg = (struct callers_data *) varg;
   uintptr pc;
+  int ip_before_insn = 0;
 
+#ifdef HAVE_GETIPINFO
+  pc = _Unwind_GetIPInfo (context, &ip_before_insn);
+#else
   pc = _Unwind_GetIP (context);
+#endif
 
   /* FIXME: If PC is in the __morestack routine, we should ignore
      it.  */
@@ -37,6 +42,11 @@ backtrace (struct _Unwind_Context *context, void *varg)
     return _URC_END_OF_STACK;
   else
     {
+      /* Here PC will be the return address.  We actually want the
+	 address of the call instruction, so back up one byte and
+	 count on the lookup routines handling that correctly.  */
+      if (!ip_before_insn)
+	--pc;
       arg->pcbuf[arg->index] = pc;
       ++arg->index;
     }
@@ -48,7 +58,7 @@ runtime_callers (int32 skip, uintptr *pcbuf, int32 m)
 {
   struct callers_data arg;
 
-  arg.skip = skip;
+  arg.skip = skip + 1;
   arg.pcbuf = pcbuf;
   arg.index = 0;
   arg.max = m;
diff --git a/libgo/runtime/mprof.goc b/libgo/runtime/mprof.goc
index e40dd61..c61c65c 100644
--- a/libgo/runtime/mprof.goc
+++ b/libgo/runtime/mprof.goc
@@ -225,11 +225,7 @@ runtime_MProf_Malloc(void *p, uintptr size)
 		return;
 
 	m->nomemprof++;
-#if 0
 	nstk = runtime_callers(1, stk, 32);
-#else
-	nstk = 0;
-#endif
 	runtime_lock(&proflock);
 	b = stkbucket(stk, nstk, true);
 	b->recent_allocs++;
diff --git a/libgo/runtime/runtime.c b/libgo/runtime/runtime.c
index 78c865b..d1ce26d 100644
--- a/libgo/runtime/runtime.c
+++ b/libgo/runtime/runtime.c
@@ -211,22 +211,3 @@ runtime_cputicks(void)
   return 0;
 #endif
 }
-
-struct funcline_go_return
-{
-  String retfile;
-  int32 retline;
-};
-
-struct funcline_go_return
-runtime_funcline_go(void *f, uintptr targetpc)
-  __asm__("libgo_runtime.runtime.funcline_go");
-
-struct funcline_go_return
-runtime_funcline_go(void *f __attribute__((unused)),
-		    uintptr targetpc __attribute__((unused)))
-{
-  struct funcline_go_return ret;
-  runtime_memclr(&ret, sizeof ret);
-  return ret;
-}
diff --git a/libgo/runtime/runtime.h b/libgo/runtime/runtime.h
index 40c59a8..e012e18 100644
--- a/libgo/runtime/runtime.h
+++ b/libgo/runtime/runtime.h
@@ -48,6 +48,7 @@ typedef unsigned int uintptr __attribute__ ((mode (pointer)));
 
 typedef	uint8			bool;
 typedef	uint8			byte;
+typedef	struct	Func		Func;
 typedef	struct	G		G;
 typedef	union	Lock		Lock;
 typedef	struct	M		M;
@@ -201,6 +202,14 @@ enum
 #define NSIG 32
 #endif
 
+// NOTE(rsc): keep in sync with extern.go:/type.Func.
+// Eventually, the loaded symbol table should be closer to this form.
+struct	Func
+{
+	String	name;
+	uintptr	entry;	// entry pc
+};
+
 /* Macros.  */
 
 #ifdef GOOS_windows