internal/coverage/cfile: remove more //go:linkname usage

Move code so that basic imports work instead
of //go:linkname for metadata lists.

For #67401.

Change-Id: Id02075570befc45a9426559aad2137ab540928b2
Reviewed-on: https://go-review.googlesource.com/c/go/+/585915
Reviewed-by: Than McIntosh <thanm@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>

src/go/build/deps_test.go

@@ -39,23 +39,34 @@ import (
 var depsRules = `
 	# No dependencies allowed for any of these packages.
 	NONE
-	< cmp, container/list, container/ring,
+	< unsafe
-	  internal/cfg, internal/coverage, internal/coverage/rtcov,
+	< cmp,
-	  internal/coverage/uleb128, internal/coverage/calloc,
+	  container/list,
-	  internal/goarch, internal/godebugs,
+	  container/ring,
-	  internal/goexperiment, internal/goos, internal/byteorder,
+	  internal/byteorder,
-	  internal/goversion, internal/nettrace, internal/platform,
+	  internal/cfg,
-	  internal/profilerecord, internal/trace/traceviewer/format,
+	  internal/coverage,
+	  internal/coverage/rtcov,
+	  internal/coverage/uleb128,
+	  internal/coverage/calloc,
+	  internal/cpu,
+	  internal/goarch,
+	  internal/godebugs,
+	  internal/goexperiment,
+	  internal/goos,
+	  internal/goversion,
+	  internal/nettrace,
+	  internal/platform,
+	  internal/profilerecord,
+	  internal/trace/traceviewer/format,
 	  log/internal,
-	  unicode/utf8, unicode/utf16, unicode,
+	  math/bits,
-	  unsafe;
+	  unicode,
+	  unicode/utf8,
+	  unicode/utf16;
 
-	# internal/abi depends only on internal/goarch and unsafe.
+	internal/goarch < internal/abi;
-	internal/goarch, unsafe < internal/abi;
+	internal/byteorder, internal/goarch < internal/chacha8rand;
-
-	internal/byteorder, internal/goarch, unsafe < internal/chacha8rand;
-
-	unsafe < internal/cpu;
 
 	# RUNTIME is the core runtime group of packages, all of them very light-weight.
 	internal/abi,
@@ -66,7 +77,8 @@ var depsRules = `
 	internal/godebugs,
 	internal/goexperiment,
 	internal/goos,
-	internal/profilerecord
+	internal/profilerecord,
+	math/bits
 	< internal/bytealg
 	< internal/stringslite
 	< internal/itoa
@@ -86,22 +98,17 @@ var depsRules = `
 	< internal/godebug
 	< internal/reflectlite
 	< errors
-	< internal/oserror, math/bits
+	< internal/oserror;
+
+	cmp, internal/race, math/bits
 	< iter
+	< maps, slices;
+
+	internal/oserror, maps, slices
 	< RUNTIME;
 
-	RUNTIME, unsafe
+	RUNTIME
-	< maps;
+	< sort
-
-	# slices depends on unsafe for overlapping check, cmp for comparison
-	# semantics, and math/bits for # calculating bitlength of numbers.
-	RUNTIME, unsafe, cmp, math/bits
-	< slices;
-
-	RUNTIME, slices
-	< sort;
-
-	sort
 	< container/heap;
 
 	RUNTIME
@@ -663,7 +670,7 @@ var depsRules = `
 	< internal/trace/traceviewer;
 
 	# Coverage.
-	FMT, crypto/md5, encoding/binary, regexp, sort, text/tabwriter, unsafe,
+	FMT, crypto/md5, encoding/binary, regexp, sort, text/tabwriter,
 	internal/coverage, internal/coverage/uleb128
 	< internal/coverage/cmerge,
 	  internal/coverage/pods,

src/internal/coverage/cfile/apis.go

@@ -7,6 +7,7 @@ package cfile
 import (
 	"fmt"
 	"internal/coverage"
+	"internal/coverage/rtcov"
 	"io"
 	"sync/atomic"
 	"unsafe"
@@ -17,7 +18,7 @@ func WriteMetaDir(dir string) error {
 	if !finalHashComputed {
 		return fmt.Errorf("error: no meta-data available (binary not built with -cover?)")
 	}
-	return emitMetaDataToDirectory(dir, getCovMetaList())
+	return emitMetaDataToDirectory(dir, rtcov.Meta.List)
 }
 
 // WriteMeta implements [runtime/coverage.WriteMeta].
@@ -28,7 +29,7 @@ func WriteMeta(w io.Writer) error {
 	if !finalHashComputed {
 		return fmt.Errorf("error: no meta-data available (binary not built with -cover?)")
 	}
-	ml := getCovMetaList()
+	ml := rtcov.Meta.List
 	return writeMetaData(w, ml, cmode, cgran, finalHash)
 }
 
@@ -57,7 +58,7 @@ func WriteCounters(w io.Writer) error {
 		return fmt.Errorf("meta-data not written yet, unable to write counter data")
 	}
 
-	pm := getCovPkgMap()
+	pm := rtcov.Meta.PkgMap
 	s := &emitState{
 		counterlist: cl,
 		pkgmap:      pm,

src/internal/coverage/cfile/emit.go

@@ -29,25 +29,13 @@ import (
 // emitted at the end of code coverage testing runs, from instrumented
 // executables.
 
-// getCovMetaList returns a list of meta-data blobs registered
-// for the currently executing instrumented program. It is defined in the
-// runtime.
-//go:linkname getCovMetaList
-func getCovMetaList() []rtcov.CovMetaBlob
-
 // getCovCounterList returns a list of counter-data blobs registered
 // for the currently executing instrumented program. It is defined in the
 // runtime.
+//
 //go:linkname getCovCounterList
 func getCovCounterList() []rtcov.CovCounterBlob
 
-// getCovPkgMap returns a map storing the remapped package IDs for
-// hard-coded runtime packages (see internal/coverage/pkgid.go for
-// more on why hard-coded package IDs are needed). This function
-// is defined in the runtime.
-//go:linkname getCovPkgMap
-func getCovPkgMap() map[int]int
-
 // emitState holds useful state information during the emit process.
 //
 // When an instrumented program finishes execution and starts the
@@ -180,7 +168,7 @@ func granClash(g coverage.CounterGranularity) bool {
 // all meta-data blobs and capturing os args.
 func prepareForMetaEmit() ([]rtcov.CovMetaBlob, error) {
 	// Ask the runtime for the list of coverage meta-data symbols.
-	ml := getCovMetaList()
+	ml := rtcov.Meta.List
 
 	// In the normal case (go build -o prog.exe ... ; ./prog.exe)
 	// len(ml) will always be non-zero, but we check here since at
@@ -210,7 +198,7 @@ func prepareForMetaEmit() ([]rtcov.CovMetaBlob, error) {
 			}
 			fmt.Fprintf(os.Stderr, "\n")
 		}
-		pm := getCovPkgMap()
+		pm := rtcov.Meta.PkgMap
 		fmt.Fprintf(os.Stderr, "=+= remap table:\n")
 		for from, to := range pm {
 			fmt.Fprintf(os.Stderr, "=+= from %d to %d\n",
@@ -310,7 +298,7 @@ func emitCounterDataToDirectory(outdir string) error {
 	}
 
 	// Ask the runtime for the list of coverage counter symbols.
-	pm := getCovPkgMap()
+	pm := rtcov.Meta.PkgMap
 	s := &emitState{
 		counterlist: cl,
 		pkgmap:      pm,
@@ -591,8 +579,8 @@ func MarkProfileEmitted(val bool) {
 }
 
 func reportErrorInHardcodedList(slot, pkgID int32, fnID, nCtrs uint32) {
-	metaList := getCovMetaList()
+	metaList := rtcov.Meta.List
-	pkgMap := getCovPkgMap()
+	pkgMap := rtcov.Meta.PkgMap
 
 	println("internal error in coverage meta-data tracking:")
 	println("encountered bad pkgID:", pkgID, " at slot:", slot,

src/internal/coverage/cfile/testsupport.go

@@ -14,6 +14,7 @@ import (
 	"internal/coverage/decodecounter"
 	"internal/coverage/decodemeta"
 	"internal/coverage/pods"
+	"internal/coverage/rtcov"
 	"internal/runtime/atomic"
 	"io"
 	"os"
@@ -33,7 +34,7 @@ func ProcessCoverTestDir(dir string, cfile string, cm string, cpkg string, w io.
 	}
 
 	// Emit meta-data and counter data.
-	ml := getCovMetaList()
+	ml := rtcov.Meta.List
 	if len(ml) == 0 {
 		// This corresponds to the case where we have a package that
 		// contains test code but no functions (which is fine). In this

src/internal/coverage/rtcov/rtcov.go

@@ -4,8 +4,10 @@
 
 package rtcov
 
+import "unsafe"
+
 // This package contains types whose structure is shared between
-// the runtime package and the "runtime/coverage" package.
+// the runtime package and the "runtime/coverage" implementation.
 
 // CovMetaBlob is a container for holding the meta-data symbol (an
 // RODATA variable) for an instrumented Go package. Here "p" points to
@@ -32,3 +34,55 @@ type CovCounterBlob struct {
 	Counters *uint32
 	Len      uint64
 }
+
+// Meta is the top-level container for bits of state related to
+// code coverage meta-data in the runtime.
+var Meta struct {
+	// List contains the list of currently registered meta-data
+	// blobs for the running program.
+	List []CovMetaBlob
+
+	// PkgMap records mappings from hard-coded package IDs to
+	// slots in the List above.
+	PkgMap map[int]int
+
+	// Set to true if we discover a package mapping glitch.
+	hardCodedListNeedsUpdating bool
+}
+
+// AddMeta is invoked during package "init" functions by the
+// compiler when compiling for coverage instrumentation; here 'p' is a
+// meta-data blob of length 'dlen' for the package in question, 'hash'
+// is a compiler-computed md5.sum for the blob, 'pkpath' is the
+// package path, 'pkid' is the hard-coded ID that the compiler is
+// using for the package (or -1 if the compiler doesn't think a
+// hard-coded ID is needed), and 'cmode'/'cgran' are the coverage
+// counter mode and granularity requested by the user. Return value is
+// the ID for the package for use by the package code itself,
+// or 0 for impossible errors.
+func AddMeta(p unsafe.Pointer, dlen uint32, hash [16]byte, pkgpath string, pkgid int, cmode uint8, cgran uint8) uint32 {
+	slot := len(Meta.List)
+	Meta.List = append(Meta.List, CovMetaBlob{
+		P:                  (*byte)(p),
+		Len:                dlen,
+		Hash:               hash,
+		PkgPath:            pkgpath,
+		PkgID:              pkgid,
+		CounterMode:        cmode,
+		CounterGranularity: cgran,
+	})
+	if pkgid != -1 {
+		if Meta.PkgMap == nil {
+			Meta.PkgMap = make(map[int]int)
+		}
+		if _, ok := Meta.PkgMap[pkgid]; ok {
+			return 0
+		}
+		// Record the real slot (position on meta-list) for this
+		// package; we'll use the map to fix things up later on.
+		Meta.PkgMap[pkgid] = slot
+	}
+
+	// ID zero is reserved as invalid.
+	return uint32(slot + 1)
+}

src/runtime/covermeta.go

@@ -9,64 +9,12 @@ import (
 	"unsafe"
 )
 
-// covMeta is the top-level container for bits of state related to
+// The compiler emits calls to runtime.addCovMeta
-// code coverage meta-data in the runtime.
+// but this code has moved to rtcov.AddMeta.
-var covMeta struct {
+func addCovMeta(p unsafe.Pointer, dlen uint32, hash [16]byte, pkgpath string, pkgid int, cmode uint8, cgran uint8) uint32 {
-	// metaList contains the list of currently registered meta-data
+	id := rtcov.AddMeta(p, dlen, hash, pkgpath, pkgid, cmode, cgran)
-	// blobs for the running program.
+	if id == 0 {
-	metaList []rtcov.CovMetaBlob
+		throw("runtime.addCovMeta: coverage package map collision")
-
-	// pkgMap records mappings from hard-coded package IDs to
-	// slots in the covMetaList above.
-	pkgMap map[int]int
-
-	// Set to true if we discover a package mapping glitch.
-	hardCodedListNeedsUpdating bool
-}
-
-// addCovMeta is invoked during package "init" functions by the
-// compiler when compiling for coverage instrumentation; here 'p' is a
-// meta-data blob of length 'dlen' for the package in question, 'hash'
-// is a compiler-computed md5.sum for the blob, 'pkpath' is the
-// package path, 'pkid' is the hard-coded ID that the compiler is
-// using for the package (or -1 if the compiler doesn't think a
-// hard-coded ID is needed), and 'cmode'/'cgran' are the coverage
-// counter mode and granularity requested by the user. Return value is
-// the ID for the package for use by the package code itself.
-func addCovMeta(p unsafe.Pointer, dlen uint32, hash [16]byte, pkpath string, pkid int, cmode uint8, cgran uint8) uint32 {
-	slot := len(covMeta.metaList)
-	covMeta.metaList = append(covMeta.metaList,
-		rtcov.CovMetaBlob{
-			P:                  (*byte)(p),
-			Len:                dlen,
-			Hash:               hash,
-			PkgPath:            pkpath,
-			PkgID:              pkid,
-			CounterMode:        cmode,
-			CounterGranularity: cgran,
-		})
-	if pkid != -1 {
-		if covMeta.pkgMap == nil {
-			covMeta.pkgMap = make(map[int]int)
-		}
-		if _, ok := covMeta.pkgMap[pkid]; ok {
-			throw("runtime.addCovMeta: coverage package map collision")
-		}
-		// Record the real slot (position on meta-list) for this
-		// package; we'll use the map to fix things up later on.
-		covMeta.pkgMap[pkid] = slot
 	}
-
+	return id
-	// ID zero is reserved as invalid.
-	return uint32(slot + 1)
-}
-
-//go:linkname coverage_getCovMetaList internal/coverage/cfile.getCovMetaList
-func coverage_getCovMetaList() []rtcov.CovMetaBlob {
-	return covMeta.metaList
-}
-
-//go:linkname coverage_getCovPkgMap internal/coverage/cfile.getCovPkgMap
-func coverage_getCovPkgMap() map[int]int {
-	return covMeta.pkgMap
 }