runtime: clean up funcID assignment

Large enum sets should be sorted by name when the
values don't matter, as they don't here. Do that.

Also replace the large switch with a map lookup.

This CL is part of a stack adding windows/arm64
support (#36439), intended to land in the Go 1.17 cycle.
This CL is, however, not windows/arm64-specific.
It is cleanup meant to make the port (and future ports) easier.

Change-Id: Ibe727b5d8866bf4c40c96020e1f4632bde7efd59
Reviewed-on: https://go-review.googlesource.com/c/go/+/288798
Trust: Russ Cox <rsc@golang.org>
Trust: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/src/cmd/internal/objabi/funcid.go b/src/cmd/internal/objabi/funcid.go
index 1d098ee17251b379c354b01f840f53aef119c058..e921a82c0c425e438ad8b0de7203a05c652f55d9 100644 (file)
--- a/src/cmd/internal/objabi/funcid.go
+++ b/src/cmd/internal/objabi/funcid.go
@@ -4,6 +4,8 @@
 
 package objabi
 
+import "strings"
+
 // A FuncID identifies particular functions that need to be treated
 // specially by the runtime.
 // Note that in some situations involving plugins, there may be multiple
@@ -13,88 +15,69 @@ type FuncID uint8
 
 const (
        FuncID_normal FuncID = iota // not a special function
-       FuncID_runtime_main
+       FuncID_asmcgocall
+       FuncID_asyncPreempt
+       FuncID_cgocallback
+       FuncID_debugCallV1
+       FuncID_externalthreadhandler
+       FuncID_gcBgMarkWorker
        FuncID_goexit
+       FuncID_gogo
+       FuncID_gopanic
+       FuncID_handleAsyncEvent
        FuncID_jmpdefer
        FuncID_mcall
        FuncID_morestack
        FuncID_mstart
+       FuncID_panicwrap
        FuncID_rt0_go
-       FuncID_asmcgocall
-       FuncID_sigpanic
        FuncID_runfinq
-       FuncID_gcBgMarkWorker
-       FuncID_systemstack_switch
+       FuncID_runtime_main
+       FuncID_sigpanic
        FuncID_systemstack
-       FuncID_cgocallback
-       FuncID_gogo
-       FuncID_externalthreadhandler
-       FuncID_debugCallV1
-       FuncID_gopanic
-       FuncID_panicwrap
-       FuncID_handleAsyncEvent
-       FuncID_asyncPreempt
+       FuncID_systemstack_switch
        FuncID_wrapper // any autogenerated code (hash/eq algorithms, method wrappers, etc.)
 )
 
+var funcIDs = map[string]FuncID{
+       "asmcgocall":            FuncID_asmcgocall,
+       "asyncPreempt":          FuncID_asyncPreempt,
+       "cgocallback":           FuncID_cgocallback,
+       "debugCallV1":           FuncID_debugCallV1,
+       "externalthreadhandler": FuncID_externalthreadhandler,
+       "gcBgMarkWorker":        FuncID_gcBgMarkWorker,
+       "go":                    FuncID_rt0_go,
+       "goexit":                FuncID_goexit,
+       "gogo":                  FuncID_gogo,
+       "gopanic":               FuncID_gopanic,
+       "handleAsyncEvent":      FuncID_handleAsyncEvent,
+       "jmpdefer":              FuncID_jmpdefer,
+       "main":                  FuncID_runtime_main,
+       "mcall":                 FuncID_mcall,
+       "morestack":             FuncID_morestack,
+       "mstart":                FuncID_mstart,
+       "panicwrap":             FuncID_panicwrap,
+       "runfinq":               FuncID_runfinq,
+       "sigpanic":              FuncID_sigpanic,
+       "switch":                FuncID_systemstack_switch,
+       "systemstack":           FuncID_systemstack,
+
+       // Don't show in call stack but otherwise not special.
+       "deferreturn":       FuncID_wrapper,
+       "runOpenDeferFrame": FuncID_wrapper,
+       "reflectcallSave":   FuncID_wrapper,
+}
+
 // Get the function ID for the named function in the named file.
 // The function should be package-qualified.
 func GetFuncID(name string, isWrapper bool) FuncID {
        if isWrapper {
                return FuncID_wrapper
        }
-       switch name {
-       case "runtime.main":
-               return FuncID_runtime_main
-       case "runtime.goexit":
-               return FuncID_goexit
-       case "runtime.jmpdefer":
-               return FuncID_jmpdefer
-       case "runtime.mcall":
-               return FuncID_mcall
-       case "runtime.morestack":
-               return FuncID_morestack
-       case "runtime.mstart":
-               return FuncID_mstart
-       case "runtime.rt0_go":
-               return FuncID_rt0_go
-       case "runtime.asmcgocall":
-               return FuncID_asmcgocall
-       case "runtime.sigpanic":
-               return FuncID_sigpanic
-       case "runtime.runfinq":
-               return FuncID_runfinq
-       case "runtime.gcBgMarkWorker":
-               return FuncID_gcBgMarkWorker
-       case "runtime.systemstack_switch":
-               return FuncID_systemstack_switch
-       case "runtime.systemstack":
-               return FuncID_systemstack
-       case "runtime.cgocallback":
-               return FuncID_cgocallback
-       case "runtime.gogo":
-               return FuncID_gogo
-       case "runtime.externalthreadhandler":
-               return FuncID_externalthreadhandler
-       case "runtime.debugCallV1":
-               return FuncID_debugCallV1
-       case "runtime.gopanic":
-               return FuncID_gopanic
-       case "runtime.panicwrap":
-               return FuncID_panicwrap
-       case "runtime.handleAsyncEvent":
-               return FuncID_handleAsyncEvent
-       case "runtime.asyncPreempt":
-               return FuncID_asyncPreempt
-       case "runtime.deferreturn":
-               // Don't show in the call stack (used when invoking defer functions)
-               return FuncID_wrapper
-       case "runtime.runOpenDeferFrame":
-               // Don't show in the call stack (used when invoking defer functions)
-               return FuncID_wrapper
-       case "runtime.reflectcallSave":
-               // Don't show in the call stack (used when invoking defer functions)
-               return FuncID_wrapper
+       if strings.HasPrefix(name, "runtime.") {
+               if id, ok := funcIDs[name[len("runtime."):]]; ok {
+                       return id
+               }
        }
        return FuncID_normal
 }

diff --git a/src/runtime/symtab.go b/src/runtime/symtab.go
index 7667f23f1dba734fae6d4bbbe9f5837d383be6c0..fc93c00c2d70628a1955b55052a02b4f6908b592 100644 (file)
--- a/src/runtime/symtab.go
+++ b/src/runtime/symtab.go
@@ -308,27 +308,27 @@ type funcID uint8
 
 const (
        funcID_normal funcID = iota // not a special function
-       funcID_runtime_main
+       funcID_asmcgocall
+       funcID_asyncPreempt
+       funcID_cgocallback
+       funcID_debugCallV1
+       funcID_externalthreadhandler
+       funcID_gcBgMarkWorker
        funcID_goexit
+       funcID_gogo
+       funcID_gopanic
+       funcID_handleAsyncEvent
        funcID_jmpdefer
        funcID_mcall
        funcID_morestack
        funcID_mstart
+       funcID_panicwrap
        funcID_rt0_go
-       funcID_asmcgocall
-       funcID_sigpanic
        funcID_runfinq
-       funcID_gcBgMarkWorker
-       funcID_systemstack_switch
+       funcID_runtime_main
+       funcID_sigpanic
        funcID_systemstack
-       funcID_cgocallback
-       funcID_gogo
-       funcID_externalthreadhandler
-       funcID_debugCallV1
-       funcID_gopanic
-       funcID_panicwrap
-       funcID_handleAsyncEvent
-       funcID_asyncPreempt
+       funcID_systemstack_switch
        funcID_wrapper // any autogenerated code (hash/eq algorithms, method wrappers, etc.)
 )