[dev.regabi] cmd/compile: clean up debug flag (-d) handling [generated]

The debug table is not as haphazard as flags, but there are still
a few mismatches between command-line names and variable names.
This CL moves them all into a consistent home (var Debug, like var Flag).

Code updated automatically using the rf command below.
A followup CL will make a few manual cleanups, leaving this CL
completely automated and easier to regenerate during merge
conflicts.

[git-generate]
cd src/cmd/compile/internal/gc
rf '
	add main.go var Debug struct{}
	mv Debug_append Debug.Append
	mv Debug_checkptr Debug.Checkptr
	mv Debug_closure Debug.Closure
	mv Debug_compilelater Debug.CompileLater
	mv disable_checknil Debug.DisableNil
	mv debug_dclstack Debug.DclStack
	mv Debug_gcprog Debug.GCProg
	mv Debug_libfuzzer Debug.Libfuzzer
	mv Debug_checknil Debug.Nil
	mv Debug_panic Debug.Panic
	mv Debug_slice Debug.Slice
	mv Debug_typeassert Debug.TypeAssert
	mv Debug_wb Debug.WB
	mv Debug_export Debug.Export
	mv Debug_pctab Debug.PCTab
	mv Debug_locationlist Debug.LocationLists
	mv Debug_typecheckinl Debug.TypecheckInl
	mv Debug_gendwarfinl Debug.DwarfInl
	mv Debug_softfloat Debug.SoftFloat
	mv Debug_defer Debug.Defer
	mv Debug_dumpptrs Debug.DumpPtrs

	mv flag.go:/parse.-d/-1,/unknown.debug/+2 parseDebug

	mv debugtab Debug parseDebug \
		debugHelpHeader debugHelpFooter \
		debug.go

	# Remove //go:generate line copied from main.go
	rm debug.go:/go:generate/-+
'

Change-Id: I625761ca5659be4052f7161a83baa00df75cca91
Reviewed-on: https://go-review.googlesource.com/c/go/+/272246
Trust: Russ Cox <rsc@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

src/cmd/compile/internal/gc/debug.go

@@ -0,0 +1,167 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gc
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+	"strings"
+
+	"cmd/compile/internal/ssa"
+	"cmd/internal/objabi"
+)
+
+// Debug arguments.
+// These can be specified with the -d flag, as in "-d nil"
+// to set the debug_checknil variable.
+// Multiple options can be comma-separated.
+// Each option accepts an optional argument, as in "gcprog=2"
+var debugtab = []struct {
+	name string
+	help string
+	val  interface{} // must be *int or *string
+}{
+	{"append", "print information about append compilation", &Debug.Append},
+	{"checkptr", "instrument unsafe pointer conversions", &Debug.Checkptr},
+	{"closure", "print information about closure compilation", &Debug.Closure},
+	{"compilelater", "compile functions as late as possible", &Debug.CompileLater},
+	{"disablenil", "disable nil checks", &Debug.DisableNil},
+	{"dclstack", "run internal dclstack check", &Debug.DclStack},
+	{"dumpptrs", "show Node pointer values in Dump/dumplist output", &Debug.DumpPtrs},
+	{"gcprog", "print dump of GC programs", &Debug.GCProg},
+	{"libfuzzer", "coverage instrumentation for libfuzzer", &Debug.Libfuzzer},
+	{"nil", "print information about nil checks", &Debug.Nil},
+	{"panic", "do not hide any compiler panic", &Debug.Panic},
+	{"slice", "print information about slice compilation", &Debug.Slice},
+	{"typeassert", "print information about type assertion inlining", &Debug.TypeAssert},
+	{"wb", "print information about write barriers", &Debug.WB},
+	{"export", "print export data", &Debug.Export},
+	{"pctab", "print named pc-value table", &Debug.PCTab},
+	{"locationlists", "print information about DWARF location list creation", &Debug.LocationLists},
+	{"typecheckinl", "eager typechecking of inline function bodies", &Debug.TypecheckInl},
+	{"dwarfinl", "print information about DWARF inlined function creation", &Debug.DwarfInl},
+	{"softfloat", "force compiler to emit soft-float code", &Debug.SoftFloat},
+	{"defer", "print information about defer compilation", &Debug.Defer},
+	{"fieldtrack", "enable fieldtracking", &objabi.Fieldtrack_enabled},
+}
+
+var Debug struct {
+	Append        int
+	Checkptr      int
+	Closure       int
+	CompileLater  int
+	DisableNil    int
+	DclStack      int
+	GCProg        int
+	Libfuzzer     int
+	Nil           int
+	Panic         int
+	Slice         int
+	TypeAssert    int
+	WB            int
+	Export        int
+	PCTab         string
+	LocationLists int
+	TypecheckInl  int
+	DwarfInl      int
+	SoftFloat     int
+	Defer         int
+	DumpPtrs      int
+}
+
+func parseDebug() {
+	// parse -d argument
+	if Flag.LowerD != "" {
+	Split:
+		for _, name := range strings.Split(Flag.LowerD, ",") {
+			if name == "" {
+				continue
+			}
+			// display help about the -d option itself and quit
+			if name == "help" {
+				fmt.Print(debugHelpHeader)
+				maxLen := len("ssa/help")
+				for _, t := range debugtab {
+					if len(t.name) > maxLen {
+						maxLen = len(t.name)
+					}
+				}
+				for _, t := range debugtab {
+					fmt.Printf("\t%-*s\t%s\n", maxLen, t.name, t.help)
+				}
+				// ssa options have their own help
+				fmt.Printf("\t%-*s\t%s\n", maxLen, "ssa/help", "print help about SSA debugging")
+				fmt.Print(debugHelpFooter)
+				os.Exit(0)
+			}
+			val, valstring, haveInt := 1, "", true
+			if i := strings.IndexAny(name, "=:"); i >= 0 {
+				var err error
+				name, valstring = name[:i], name[i+1:]
+				val, err = strconv.Atoi(valstring)
+				if err != nil {
+					val, haveInt = 1, false
+				}
+			}
+			for _, t := range debugtab {
+				if t.name != name {
+					continue
+				}
+				switch vp := t.val.(type) {
+				case nil:
+					// Ignore
+				case *string:
+					*vp = valstring
+				case *int:
+					if !haveInt {
+						log.Fatalf("invalid debug value %v", name)
+					}
+					*vp = val
+				default:
+					panic("bad debugtab type")
+				}
+				continue Split
+			}
+			// special case for ssa for now
+			if strings.HasPrefix(name, "ssa/") {
+				// expect form ssa/phase/flag
+				// e.g. -d=ssa/generic_cse/time
+				// _ in phase name also matches space
+				phase := name[4:]
+				flag := "debug" // default flag is debug
+				if i := strings.Index(phase, "/"); i >= 0 {
+					flag = phase[i+1:]
+					phase = phase[:i]
+				}
+				err := ssa.PhaseOption(phase, flag, val, valstring)
+				if err != "" {
+					log.Fatalf(err)
+				}
+				continue Split
+			}
+			log.Fatalf("unknown debug key -d %s\n", name)
+		}
+	}
+}
+
+const debugHelpHeader = `usage: -d arg[,arg]* and arg is <key>[=<value>]
+
+<key> is one of:
+
+`
+
+const debugHelpFooter = `
+<value> is key-specific.
+
+Key "checkptr" supports values:
+	"0": instrumentation disabled
+	"1": conversions involving unsafe.Pointer are instrumented
+	"2": conversions to unsafe.Pointer force heap allocation
+
+Key "pctab" supports values:
+	"pctospadj", "pctofile", "pctoline", "pctoinline", "pctopcdata"
+`