runtime: use funcdata to supply garbage collection information

This CL introduces a FUNCDATA number for runtime-specific
garbage collection metadata, changes the C and Go compilers
to emit that metadata, and changes the runtime to expect it.

The old pseudo-instructions that carried this information
are gone, as is the linker code to process them.

R=golang-dev, dvyukov, cshapiro
CC=golang-dev
https://golang.org/cl/11406044

1 files changed, 4 insertions, 23 deletions

diff --git a/src/pkg/runtime/traceback_arm.c b/src/pkg/runtime/traceback_arm.c
index 5aea699e34..563ba28c94 100644
--- a/src/pkg/runtime/traceback_arm.c
+++ b/src/pkg/runtime/traceback_arm.c
@@ -95,7 +95,9 @@ runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip,
 					runtime·throw("unknown caller pc");
 			}
 		}
-			
+
+		frame.varp = (byte*)frame.fp;
+
 		// Derive size of arguments.
 		// Most functions have a fixed-size argument block,
 		// so we can use metadata about the function f.
@@ -121,27 +123,6 @@ runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip,
 			}
 		}
 
-		// Derive location and size of local variables.
-		if(frame.fp == frame.sp) {
-			// Function has not created a frame for itself yet.
-			frame.varp = nil;
-			frame.varlen = 0;
-		} else if(f->locals == 0) {
-			// Assume no information, so use whole frame.
-			// TODO: Distinguish local==0 from local==unknown.
-			frame.varp = (byte*)frame.sp;
-			frame.varlen = frame.fp - frame.sp;
-		} else {
-			if(f->locals > frame.fp - frame.sp) {
-				runtime·printf("runtime: inconsistent locals=%p frame=%p fp=%p sp=%p for %s\n", (uintptr)f->locals, (uintptr)f->frame, frame.fp, frame.sp, runtime·funcname(f));
-				if(callback != nil)
-					runtime·throw("invalid stack");
-			}
-			frame.varp = (byte*)frame.fp - f->locals;
-			frame.varlen = f->locals;
-		}
-
-
 		if(skip > 0) {
 			skip--;
 			goto skipped;
@@ -203,7 +184,7 @@ runtime·gentraceback(uintptr pc0, uintptr sp0, uintptr lr0, G *gp, int32 skip,
 			frame.fn = f = runtime·findfunc(frame.pc);
 			if(f == nil)
 				frame.pc = x;
-			else if (f->frame == 0)
+			else if(f->frame == 0)
 				frame.lr = x;
 		}
 	}