runtime: print signal information during panic

$ 6.out
panic: runtime error: invalid memory address or nil pointer dereference

[signal 11 code=0x1 addr=0x0 pc=0x1c16]

runtime.panic+0xa7 /Users/rsc/g/go/src/pkg/runtime/proc.c:1089
	runtime.panic(0xf6c8, 0x25c010)
runtime.panicstring+0x69 /Users/rsc/g/go/src/pkg/runtime/runtime.c:88
	runtime.panicstring(0x24814, 0x0)
runtime.sigpanic+0x144 /Users/rsc/g/go/src/pkg/runtime/darwin/thread.c:465
	runtime.sigpanic()
main.f+0x16 /Users/rsc/x.go:5
	main.f()
main.main+0x1c /Users/rsc/x.go:9
	main.main()
runtime.mainstart+0xf /Users/rsc/g/go/src/pkg/runtime/amd64/asm.s:77
	runtime.mainstart()
runtime.goexit /Users/rsc/g/go/src/pkg/runtime/proc.c:149
	runtime.goexit()

R=r
CC=golang-dev
https://golang.org/cl/4036042

1 files changed, 6 insertions, 1 deletions

diff --git a/src/pkg/runtime/runtime.c b/src/pkg/runtime/runtime.c
index 9d3efe966d..513675240f 100644
--- a/src/pkg/runtime/runtime.c
+++ b/src/pkg/runtime/runtime.c
@@ -30,11 +30,16 @@ runtime·dopanic(int32 unused)
 	}
 	runtime·panicking++;
 
-	runtime·printf("\npanic PC=%X\n", (uint64)(uintptr)&unused);
+	if(g->sig != 0)
+		runtime·printf("\n[signal %d code=%p addr=%p pc=%p]\n",
+			g->sig, g->sigcode0, g->sigcode1, g->sigpc);
+
+	runtime·printf("\n");
 	if(runtime·gotraceback()){
 		runtime·traceback(runtime·getcallerpc(&unused), runtime·getcallersp(&unused), 0, g);
 		runtime·tracebackothers(g);
 	}
+	
 	runtime·breakpoint();  // so we can grab it in a debugger
 	runtime·exit(2);
 }