1 files changed, 209 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/coverage/cover.go b/src/cmd/compile/internal/coverage/cover.go
new file mode 100644
index 0000000..688728d
--- /dev/null
+++ b/src/cmd/compile/internal/coverage/cover.go
@@ -0,0 +1,209 @@
+// Copyright 2022 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 coverage
+
+// This package contains support routines for coverage "fixup" in the
+// compiler, which happens when compiling a package whose source code
+// has been run through "cmd/cover" to add instrumentation. The two
+// important entry points are FixupVars (called prior to package init
+// generation) and FixupInit (called following package init
+// generation).
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/typecheck"
+	"cmd/compile/internal/types"
+	"cmd/internal/objabi"
+	"internal/coverage"
+	"strconv"
+	"strings"
+)
+
+// Names records state information collected in the first fixup
+// phase so that it can be passed to the second fixup phase.
+type Names struct {
+	MetaVar     *ir.Name
+	PkgIdVar    *ir.Name
+	InitFn      *ir.Func
+	CounterMode coverage.CounterMode
+	CounterGran coverage.CounterGranularity
+}
+
+// FixupVars is the first of two entry points for coverage compiler
+// fixup. It collects and returns the package ID and meta-data
+// variables being used for this "-cover" build, along with the
+// coverage counter mode and granularity. It also reclassifies selected
+// variables (for example, tagging coverage counter variables with
+// flags so that they can be handled properly downstream).
+func FixupVars() Names {
+	metaVarName := base.Flag.Cfg.CoverageInfo.MetaVar
+	pkgIdVarName := base.Flag.Cfg.CoverageInfo.PkgIdVar
+	counterMode := base.Flag.Cfg.CoverageInfo.CounterMode
+	counterGran := base.Flag.Cfg.CoverageInfo.CounterGranularity
+	counterPrefix := base.Flag.Cfg.CoverageInfo.CounterPrefix
+	var metavar *ir.Name
+	var pkgidvar *ir.Name
+
+	ckTypSanity := func(nm *ir.Name, tag string) {
+		if nm.Type() == nil || nm.Type().HasPointers() {
+			base.Fatalf("unsuitable %s %q mentioned in coveragecfg, improper type '%v'", tag, nm.Sym().Name, nm.Type())
+		}
+	}
+
+	for _, n := range typecheck.Target.Decls {
+		as, ok := n.(*ir.AssignStmt)
+		if !ok {
+			continue
+		}
+		nm, ok := as.X.(*ir.Name)
+		if !ok {
+			continue
+		}
+		s := nm.Sym()
+		switch s.Name {
+		case metaVarName:
+			metavar = nm
+			ckTypSanity(nm, "metavar")
+			nm.MarkReadonly()
+			continue
+		case pkgIdVarName:
+			pkgidvar = nm
+			ckTypSanity(nm, "pkgidvar")
+			nm.SetCoverageAuxVar(true)
+			s := nm.Linksym()
+			s.Type = objabi.SCOVERAGE_AUXVAR
+			continue
+		}
+		if strings.HasPrefix(s.Name, counterPrefix) {
+			ckTypSanity(nm, "countervar")
+			nm.SetCoverageCounter(true)
+			s := nm.Linksym()
+			s.Type = objabi.SCOVERAGE_COUNTER
+		}
+	}
+	cm := coverage.ParseCounterMode(counterMode)
+	if cm == coverage.CtrModeInvalid {
+		base.Fatalf("bad setting %q for covermode in coveragecfg:",
+			counterMode)
+	}
+	var cg coverage.CounterGranularity
+	switch counterGran {
+	case "perblock":
+		cg = coverage.CtrGranularityPerBlock
+	case "perfunc":
+		cg = coverage.CtrGranularityPerFunc
+	default:
+		base.Fatalf("bad setting %q for covergranularity in coveragecfg:",
+			counterGran)
+	}
+
+	return Names{
+		MetaVar:     metavar,
+		PkgIdVar:    pkgidvar,
+		CounterMode: cm,
+		CounterGran: cg,
+	}
+}
+
+// FixupInit is the second main entry point for coverage compiler
+// fixup. It adds calls to the pkg init function as appropriate to
+// register coverage-related variables with the runtime.
+func FixupInit(cnames Names) {
+	for _, n := range typecheck.Target.Decls {
+		if fn, ok := n.(*ir.Func); ok && ir.FuncName(fn) == "init" {
+			cnames.InitFn = fn
+			break
+		}
+	}
+	if cnames.InitFn == nil {
+		panic("unexpected (no init func for -cover build)")
+	}
+
+	hashv, len := metaHashAndLen()
+	if cnames.CounterMode != coverage.CtrModeTestMain {
+		registerMeta(cnames, hashv, len)
+	}
+	if base.Ctxt.Pkgpath == "main" {
+		addInitHookCall(cnames.InitFn, cnames.CounterMode)
+	}
+}
+
+func metaHashAndLen() ([16]byte, int) {
+
+	// Read meta-data hash from config entry.
+	mhash := base.Flag.Cfg.CoverageInfo.MetaHash
+	if len(mhash) != 32 {
+		base.Fatalf("unexpected: got metahash length %d want 32", len(mhash))
+	}
+	var hv [16]byte
+	for i := 0; i < 16; i++ {
+		nib := string(mhash[i*2 : i*2+2])
+		x, err := strconv.ParseInt(nib, 16, 32)
+		if err != nil {
+			base.Fatalf("metahash bad byte %q", nib)
+		}
+		hv[i] = byte(x)
+	}
+
+	// Return hash and meta-data len
+	return hv, base.Flag.Cfg.CoverageInfo.MetaLen
+}
+
+func registerMeta(cnames Names, hashv [16]byte, mdlen int) {
+	// Materialize expression for hash (an array literal)
+	pos := cnames.InitFn.Pos()
+	elist := make([]ir.Node, 0, 16)
+	for i := 0; i < 16; i++ {
+		elem := ir.NewInt(int64(hashv[i]))
+		elist = append(elist, elem)
+	}
+	ht := types.NewArray(types.Types[types.TUINT8], 16)
+	hashx := ir.NewCompLitExpr(pos, ir.OCOMPLIT, ht, elist)
+
+	// Materalize expression corresponding to address of the meta-data symbol.
+	mdax := typecheck.NodAddr(cnames.MetaVar)
+	mdauspx := typecheck.ConvNop(mdax, types.Types[types.TUNSAFEPTR])
+
+	// Materialize expression for length.
+	lenx := ir.NewInt(int64(mdlen)) // untyped
+
+	// Generate a call to runtime.addCovMeta, e.g.
+	//
+	//   pkgIdVar = runtime.addCovMeta(&sym, len, hash, pkgpath, pkid, cmode, cgran)
+	//
+	fn := typecheck.LookupRuntime("addCovMeta")
+	pkid := coverage.HardCodedPkgID(base.Ctxt.Pkgpath)
+	pkIdNode := ir.NewInt(int64(pkid))
+	cmodeNode := ir.NewInt(int64(cnames.CounterMode))
+	cgranNode := ir.NewInt(int64(cnames.CounterGran))
+	pkPathNode := ir.NewString(base.Ctxt.Pkgpath)
+	callx := typecheck.Call(pos, fn, []ir.Node{mdauspx, lenx, hashx,
+		pkPathNode, pkIdNode, cmodeNode, cgranNode}, false)
+	assign := callx
+	if pkid == coverage.NotHardCoded {
+		assign = typecheck.Stmt(ir.NewAssignStmt(pos, cnames.PkgIdVar, callx))
+	}
+
+	// Tack the call onto the start of our init function. We do this
+	// early in the init since it's possible that instrumented function
+	// bodies (with counter updates) might be inlined into init.
+	cnames.InitFn.Body.Prepend(assign)
+}
+
+// addInitHookCall generates a call to runtime/coverage.initHook() and
+// inserts it into the package main init function, which will kick off
+// the process for coverage data writing (emit meta data, and register
+// an exit hook to emit counter data).
+func addInitHookCall(initfn *ir.Func, cmode coverage.CounterMode) {
+	typecheck.InitCoverage()
+	pos := initfn.Pos()
+	istest := cmode == coverage.CtrModeTestMain
+	initf := typecheck.LookupCoverage("initHook")
+	istestNode := ir.NewBool(istest)
+	args := []ir.Node{istestNode}
+	callx := typecheck.Call(pos, initf, args, false)
+	initfn.Body.Append(callx)
+}