runtime: rename getcallerfp to getfp

The previous name was wrong due to the mistaken assumption that calling
f->g->getcallerpc and f->g->getcallersp would respectively return the
pc/sp at g. However, they are actually referring to their caller's
caller, i.e. f.

Rename getcallerfp to getfp in order to stay consistent with this
naming convention.

Also see discussion on CL 463835.

For #16638

This is a redo of CL 481617 that became necessary because CL 461738
added another call site for getcallerfp().

Change-Id: If0b536e85a6c26061b65e7b5c2859fc31385d025
Reviewed-on: https://go-review.googlesource.com/c/go/+/494857
Reviewed-by: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Felix Geisendörfer <felix.geisendoerfer@datadoghq.com>

src/runtime/asm_amd64.s

@@ -2088,6 +2088,6 @@ TEXT runtime·retpolineR13(SB),NOSPLIT|NOFRAME,$0; RETPOLINE(13)
 TEXT runtime·retpolineR14(SB),NOSPLIT|NOFRAME,$0; RETPOLINE(14)
 TEXT runtime·retpolineR15(SB),NOSPLIT|NOFRAME,$0; RETPOLINE(15)
 
-TEXT ·getcallerfp<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
+TEXT ·getfp<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
 	MOVQ BP, AX
 	RET

src/runtime/asm_arm64.s

@@ -1568,6 +1568,6 @@ TEXT runtime·panicSliceConvert<ABIInternal>(SB),NOSPLIT,$0-16
 	MOVD	R3, R1
 	JMP	runtime·goPanicSliceConvert<ABIInternal>(SB)
 
-TEXT ·getcallerfp<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
+TEXT ·getfp<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
 	MOVD R29, R0
 	RET

src/runtime/export_test.go

@@ -1826,7 +1826,7 @@ func PersistentAlloc(n uintptr) unsafe.Pointer {
 // FPCallers works like Callers and uses frame pointer unwinding to populate
 // pcBuf with the return addresses of the physical frames on the stack.
 func FPCallers(pcBuf []uintptr) int {
-	return fpTracebackPCs(unsafe.Pointer(getcallerfp()), pcBuf)
+	return fpTracebackPCs(unsafe.Pointer(getfp()), pcBuf)
 }
 
 var (

src/runtime/export_windows_test.go

@@ -33,6 +33,6 @@ func NewContextStub() ContextStub {
 	var ctx context
 	ctx.set_ip(getcallerpc())
 	ctx.set_sp(getcallersp())
-	ctx.set_fp(getcallerfp())
+	ctx.set_fp(getfp())
 	return ContextStub{ctx}
 }

src/runtime/os_wasm.go

@@ -137,8 +137,9 @@ func preemptM(mp *m) {
 	// No threads, so nothing to do.
 }
 
-// getcallerfp returns the address of the frame pointer in the callers frame or 0 if not implemented.
+// getfp returns the frame pointer register of its caller or 0 if not implemented.
-func getcallerfp() uintptr { return 0 }
+// TODO: Make this a compiler intrinsic
+func getfp() uintptr { return 0 }
 
 func setProcessCPUProfiler(hz int32) {}
 func setThreadCPUProfiler(hz int32)  {}

src/runtime/stubs_386.go

@@ -19,5 +19,6 @@ func emptyfunc()
 //go:noescape
 func asmcgocall_no_g(fn, arg unsafe.Pointer)
 
-// getcallerfp returns the address of the frame pointer in the callers frame or 0 if not implemented.
+// getfp returns the frame pointer register of its caller or 0 if not implemented.
-func getcallerfp() uintptr { return 0 }
+// TODO: Make this a compiler intrinsic
+func getfp() uintptr { return 0 }

src/runtime/stubs_amd64.go

@@ -48,6 +48,6 @@ func asmcgocall_no_g(fn, arg unsafe.Pointer)
 func spillArgs()
 func unspillArgs()
 
-// getcallerfp returns the address of the frame pointer in the callers frame or 0 if not implemented.
+// getfp returns the frame pointer register of its caller or 0 if not implemented.
 // TODO: Make this a compiler intrinsic
-func getcallerfp() uintptr
+func getfp() uintptr

src/runtime/stubs_arm.go

@@ -24,5 +24,6 @@ func read_tls_fallback()
 //go:noescape
 func asmcgocall_no_g(fn, arg unsafe.Pointer)
 
-// getcallerfp returns the address of the frame pointer in the callers frame or 0 if not implemented.
+// getfp returns the frame pointer register of its caller or 0 if not implemented.
-func getcallerfp() uintptr { return 0 }
+// TODO: Make this a compiler intrinsic
+func getfp() uintptr { return 0 }

src/runtime/stubs_arm64.go

@@ -22,6 +22,6 @@ func emptyfunc()
 func spillArgs()
 func unspillArgs()
 
-// getcallerfp returns the address of the frame pointer in the callers frame or 0 if not implemented.
+// getfp returns the frame pointer register of its caller or 0 if not implemented.
 // TODO: Make this a compiler intrinsic
-func getcallerfp() uintptr
+func getfp() uintptr

src/runtime/stubs_loong64.go

@@ -10,5 +10,6 @@ package runtime
 func load_g()
 func save_g()
 
-// getcallerfp returns the address of the frame pointer in the callers frame or 0 if not implemented.
+// getfp returns the frame pointer register of its caller or 0 if not implemented.
-func getcallerfp() uintptr { return 0 }
+// TODO: Make this a compiler intrinsic
+func getfp() uintptr { return 0 }

src/runtime/stubs_mips64x.go

@@ -15,5 +15,6 @@ func save_g()
 //go:noescape
 func asmcgocall_no_g(fn, arg unsafe.Pointer)
 
-// getcallerfp returns the address of the frame pointer in the callers frame or 0 if not implemented.
+// getfp returns the frame pointer register of its caller or 0 if not implemented.
-func getcallerfp() uintptr { return 0 }
+// TODO: Make this a compiler intrinsic
+func getfp() uintptr { return 0 }

src/runtime/stubs_mipsx.go

@@ -10,5 +10,6 @@ package runtime
 func load_g()
 func save_g()
 
-// getcallerfp returns the address of the frame pointer in the callers frame or 0 if not implemented.
+// getfp returns the frame pointer register of its caller or 0 if not implemented.
-func getcallerfp() uintptr { return 0 }
+// TODO: Make this a compiler intrinsic
+func getfp() uintptr { return 0 }

src/runtime/stubs_ppc64x.go

@@ -16,5 +16,6 @@ func reginit()
 func spillArgs()
 func unspillArgs()
 
-// getcallerfp returns the address of the frame pointer in the callers frame or 0 if not implemented.
+// getfp returns the frame pointer register of its caller or 0 if not implemented.
-func getcallerfp() uintptr { return 0 }
+// TODO: Make this a compiler intrinsic
+func getfp() uintptr { return 0 }

src/runtime/stubs_riscv64.go

@@ -15,5 +15,6 @@ func save_g()
 func spillArgs()
 func unspillArgs()
 
-// getcallerfp returns the address of the frame pointer in the callers frame or 0 if not implemented.
+// getfp returns the frame pointer register of its caller or 0 if not implemented.
-func getcallerfp() uintptr { return 0 }
+// TODO: Make this a compiler intrinsic
+func getfp() uintptr { return 0 }

src/runtime/stubs_s390x.go

@@ -8,5 +8,6 @@ package runtime
 func load_g()
 func save_g()
 
-// getcallerfp returns the address of the frame pointer in the callers frame or 0 if not implemented.
+// getfp returns the frame pointer register of its caller or 0 if not implemented.
-func getcallerfp() uintptr { return 0 }
+// TODO: Make this a compiler intrinsic
+func getfp() uintptr { return 0 }

src/runtime/trace.go

@@ -970,7 +970,7 @@ func traceStackID(mp *m, pcBuf []uintptr, skip int) uint64 {
 		// Fast path: Unwind using frame pointers.
 		pcBuf[0] = uintptr(skip)
 		if curgp == gp {
-			nstk += fpTracebackPCs(unsafe.Pointer(getcallerfp()), pcBuf[1:])
+			nstk += fpTracebackPCs(unsafe.Pointer(getfp()), pcBuf[1:])
 		} else if curgp != nil {
 			// We're called on the g0 stack through mcall(fn) or systemstack(fn). To
 			// behave like gcallers above, we start unwinding from sched.bp, which