cmd/compile: move remaining instrumentation logic into ssagen

Allows removing Func.{Enter,Exit}, which were only ever used to hold
at most one function call each.

Change-Id: I8b629c82e90bac3fcbe54db89900492406c7dca6
Reviewed-on: https://go-review.googlesource.com/c/go/+/528319
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Than McIntosh <thanm@google.com>

src/cmd/compile/internal/ir/fmt.go

@@ -1129,11 +1129,6 @@ func dumpNode(w io.Writer, n Node, depth int) {
 				dumpNode(w, cv, depth+1)
 			}
 		}
-		if len(fn.Enter) > 0 {
-			indent(w, depth)
-			fmt.Fprintf(w, "%+v-Enter", n.Op())
-			dumpNodes(w, fn.Enter, depth+1)
-		}
 		if len(fn.Body) > 0 {
 			indent(w, depth)
 			fmt.Fprintf(w, "%+v-body", n.Op())

src/cmd/compile/internal/ir/func.go

@@ -56,11 +56,6 @@ type Func struct {
 	Nname    *Name        // ONAME node
 	OClosure *ClosureExpr // OCLOSURE node
 
-	// Extra entry code for the function. For example, allocate and initialize
-	// memory for escaping parameters.
-	Enter Nodes
-	Exit  Nodes
-
 	// ONAME nodes for all params/locals for this func/closure, does NOT
 	// include closurevars until transforming closures during walk.
 	// Names must be listed PPARAMs, PPARAMOUTs, then PAUTOs,
@@ -235,7 +230,6 @@ const (
 	funcNilCheckDisabled         // disable nil checks when compiling this function
 	funcInlinabilityChecked      // inliner has already determined whether the function is inlinable
 	funcNeverReturns             // function never returns (in most cases calls panic(), os.Exit(), or equivalent)
-	funcInstrumentBody           // add race/msan/asan instrumentation during SSA construction
 	funcOpenCodedDeferDisallowed // can't do open-coded defers
 	funcClosureResultsLost       // closure is called indirectly and we lost track of its results; used by escape analysis
 	funcPackageInit              // compiler emitted .init func for package
@@ -257,7 +251,6 @@ func (f *Func) HasDefer() bool                 { return f.flags&funcHasDefer !=
 func (f *Func) NilCheckDisabled() bool         { return f.flags&funcNilCheckDisabled != 0 }
 func (f *Func) InlinabilityChecked() bool      { return f.flags&funcInlinabilityChecked != 0 }
 func (f *Func) NeverReturns() bool             { return f.flags&funcNeverReturns != 0 }
-func (f *Func) InstrumentBody() bool           { return f.flags&funcInstrumentBody != 0 }
 func (f *Func) OpenCodedDeferDisallowed() bool { return f.flags&funcOpenCodedDeferDisallowed != 0 }
 func (f *Func) ClosureResultsLost() bool       { return f.flags&funcClosureResultsLost != 0 }
 func (f *Func) IsPackageInit() bool            { return f.flags&funcPackageInit != 0 }
@@ -273,7 +266,6 @@ func (f *Func) SetHasDefer(b bool)                 { f.flags.set(funcHasDefer, b
 func (f *Func) SetNilCheckDisabled(b bool)         { f.flags.set(funcNilCheckDisabled, b) }
 func (f *Func) SetInlinabilityChecked(b bool)      { f.flags.set(funcInlinabilityChecked, b) }
 func (f *Func) SetNeverReturns(b bool)             { f.flags.set(funcNeverReturns, b) }
-func (f *Func) SetInstrumentBody(b bool)           { f.flags.set(funcInstrumentBody, b) }
 func (f *Func) SetOpenCodedDeferDisallowed(b bool) { f.flags.set(funcOpenCodedDeferDisallowed, b) }
 func (f *Func) SetClosureResultsLost(b bool)       { f.flags.set(funcClosureResultsLost, b) }
 func (f *Func) SetIsPackageInit(b bool)            { f.flags.set(funcPackageInit, b) }

src/cmd/compile/internal/ir/sizeof_test.go

@@ -20,7 +20,7 @@ func TestSizeof(t *testing.T) {
 		_32bit uintptr     // size on 32bit platforms
 		_64bit uintptr     // size on 64bit platforms
 	}{
-		{Func{}, 192, 336},
+		{Func{}, 168, 288},
 		{Name{}, 96, 168},
 	}
 

src/cmd/compile/internal/ir/symtab.go

@@ -40,6 +40,8 @@ var Syms struct {
 	PanicdottypeI     *obj.LSym
 	Panicnildottype   *obj.LSym
 	Panicoverflow     *obj.LSym
+	Racefuncenter     *obj.LSym
+	Racefuncexit      *obj.LSym
 	Raceread          *obj.LSym
 	Racereadrange     *obj.LSym
 	Racewrite         *obj.LSym

src/cmd/compile/internal/loopvar/loopvar.go

@@ -487,8 +487,6 @@ func rewriteNodes(fn *ir.Func, editNodes func(c ir.Nodes) ir.Nodes) {
 		switch x := n.(type) {
 		case *ir.Func:
 			x.Body = editNodes(x.Body)
-			x.Enter = editNodes(x.Enter)
-			x.Exit = editNodes(x.Exit)
 		case *ir.InlinedCallExpr:
 			x.Body = editNodes(x.Body)
 

src/cmd/compile/internal/ssagen/ssa.go

@@ -27,6 +27,7 @@ import (
 	"cmd/compile/internal/typecheck"
 	"cmd/compile/internal/types"
 	"cmd/internal/obj"
+	"cmd/internal/objabi"
 	"cmd/internal/src"
 	"cmd/internal/sys"
 
@@ -130,6 +131,8 @@ func InitConfig() {
 	ir.Syms.Panicnildottype = typecheck.LookupRuntimeFunc("panicnildottype")
 	ir.Syms.Panicoverflow = typecheck.LookupRuntimeFunc("panicoverflow")
 	ir.Syms.Panicshift = typecheck.LookupRuntimeFunc("panicshift")
+	ir.Syms.Racefuncenter = typecheck.LookupRuntimeFunc("racefuncenter")
+	ir.Syms.Racefuncexit = typecheck.LookupRuntimeFunc("racefuncexit")
 	ir.Syms.Raceread = typecheck.LookupRuntimeFunc("raceread")
 	ir.Syms.Racereadrange = typecheck.LookupRuntimeFunc("racereadrange")
 	ir.Syms.Racewrite = typecheck.LookupRuntimeFunc("racewrite")
@@ -319,9 +322,7 @@ func buildssa(fn *ir.Func, worker int) *ssa.Func {
 	var astBuf *bytes.Buffer
 	if printssa {
 		astBuf = &bytes.Buffer{}
-		ir.FDumpList(astBuf, "buildssa-enter", fn.Enter)
 		ir.FDumpList(astBuf, "buildssa-body", fn.Body)
-		ir.FDumpList(astBuf, "buildssa-exit", fn.Exit)
 		if ssaDumpStdout {
 			fmt.Println("generating SSA for", name)
 			fmt.Print(astBuf.String())
@@ -338,6 +339,15 @@ func buildssa(fn *ir.Func, worker int) *ssa.Func {
 	}
 	s.checkPtrEnabled = ir.ShouldCheckPtr(fn, 1)
 
+	if base.Flag.Cfg.Instrumenting && fn.Pragma&ir.Norace == 0 && !fn.Linksym().ABIWrapper() {
+		if !base.Flag.Race || !objabi.LookupPkgSpecial(fn.Sym().Pkg.Path).NoRaceFunc {
+			s.instrumentMemory = true
+		}
+		if base.Flag.Race {
+			s.instrumentEnterExit = true
+		}
+	}
+
 	fe := ssafn{
 		curfn: fn,
 		log:   printssa && ssaDumpStdout,
@@ -395,10 +405,10 @@ func buildssa(fn *ir.Func, worker int) *ssa.Func {
 		// preceding the deferreturn/ret code that we don't track correctly.
 		s.hasOpenDefers = false
 	}
-	if s.hasOpenDefers && len(s.curfn.Exit) > 0 {
-		// Skip doing open defers if there is any extra exit code (likely
-		// race detection), since we will not generate that code in the
-		// case of the extra deferreturn/ret segment.
+	if s.hasOpenDefers && s.instrumentEnterExit {
+		// Skip doing open defers if we need to instrument function
+		// returns for the race detector, since we will not generate that
+		// code in the case of the extra deferreturn/ret segment.
 		s.hasOpenDefers = false
 	}
 	if s.hasOpenDefers {
@@ -541,7 +551,9 @@ func buildssa(fn *ir.Func, worker int) *ssa.Func {
 	}
 
 	// Convert the AST-based IR to the SSA-based IR
-	s.stmtList(fn.Enter)
+	if s.instrumentEnterExit {
+		s.rtcall(ir.Syms.Racefuncenter, true, nil, s.newValue0(ssa.OpGetCallerPC, types.Types[types.TUINTPTR]))
+	}
 	s.zeroResults()
 	s.paramsToHeap()
 	s.stmtList(fn.Body)
@@ -886,6 +898,8 @@ type state struct {
 	softFloat           bool
 	hasOpenDefers       bool // whether we are doing open-coded defers
 	checkPtrEnabled     bool // whether to insert checkptr instrumentation
+	instrumentEnterExit bool // whether to instrument function enter/exit
+	instrumentMemory    bool // whether to instrument memory operations
 
 	// If doing open-coded defers, list of info about the defer calls in
 	// scanning order. Hence, at exit we should run these defers in reverse
@@ -1262,7 +1276,7 @@ func (s *state) instrumentMove(t *types.Type, dst, src *ssa.Value) {
 }
 
 func (s *state) instrument2(t *types.Type, addr, addr2 *ssa.Value, kind instrumentKind) {
-	if !s.curfn.InstrumentBody() {
+	if !s.instrumentMemory {
 		return
 	}
 
@@ -2023,13 +2037,10 @@ func (s *state) exit() *ssa.Block {
 		}
 	}
 
-	var b *ssa.Block
-	var m *ssa.Value
 	// Do actual return.
 	// These currently turn into self-copies (in many cases).
 	resultFields := s.curfn.Type().Results()
 	results := make([]*ssa.Value, len(resultFields)+1, len(resultFields)+1)
-	m = s.newValue0(ssa.OpMakeResult, s.f.OwnAux.LateExpansionResultType())
 	// Store SSAable and heap-escaped PPARAMOUT variables back to stack locations.
 	for i, f := range resultFields {
 		n := f.Nname.(*ir.Name)
@@ -2055,15 +2066,18 @@ func (s *state) exit() *ssa.Block {
 		}
 	}
 
-	// Run exit code. Today, this is just racefuncexit, in -race mode.
-	// TODO(register args) this seems risky here with a register-ABI, but not clear it is right to do it earlier either.
-	// Spills in register allocation might just fix it.
-	s.stmtList(s.curfn.Exit)
+	// In -race mode, we need to call racefuncexit.
+	// Note: This has to happen after we load any heap-allocated results,
+	// otherwise races will be attributed to the caller instead.
+	if s.instrumentEnterExit {
+		s.rtcall(ir.Syms.Racefuncexit, true, nil)
+	}
 
 	results[len(results)-1] = s.mem()
+	m := s.newValue0(ssa.OpMakeResult, s.f.OwnAux.LateExpansionResultType())
 	m.AddArgs(results...)
 
-	b = s.endBlock()
+	b := s.endBlock()
 	b.Kind = ssa.BlockRet
 	b.SetControl(m)
 	if s.hasdefer && s.hasOpenDefers {

src/cmd/compile/internal/walk/race.go

@@ -1,55 +0,0 @@
-// Copyright 2012 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 walk
-
-import (
-	"cmd/compile/internal/base"
-	"cmd/compile/internal/ir"
-	"cmd/compile/internal/types"
-	"cmd/internal/objabi"
-	"cmd/internal/src"
-)
-
-// The racewalk pass is currently handled in three parts.
-//
-// First, for flag_race, it inserts calls to racefuncenter and
-// racefuncexit at the start and end (respectively) of each
-// function. This is handled below.
-//
-// Second, during buildssa, it inserts appropriate instrumentation
-// calls immediately before each memory load or store. This is handled
-// by the (*state).instrument method in ssa.go, so here we just set
-// the Func.InstrumentBody flag as needed. For background on why this
-// is done during SSA construction rather than a separate SSA pass,
-// see issue #19054.
-//
-// Third, we remove calls to racefuncenter and racefuncexit, for leaf
-// functions without instrumented operations. This is done as part of
-// ssa opt pass via special rule.
-
-// TODO(dvyukov): do not instrument initialization as writes:
-// a := make([]int, 10)
-
-func instrument(fn *ir.Func) {
-	if fn.Pragma&ir.Norace != 0 || (fn.Linksym() != nil && fn.Linksym().ABIWrapper()) {
-		return
-	}
-
-	if !base.Flag.Race || !objabi.LookupPkgSpecial(base.Ctxt.Pkgpath).NoRaceFunc {
-		fn.SetInstrumentBody(true)
-	}
-
-	if base.Flag.Race {
-		lno := base.Pos
-		base.Pos = src.NoXPos
-		var init ir.Nodes
-		fn.Enter.Prepend(mkcallstmt("racefuncenter", mkcall("getcallerpc", types.Types[types.TUINTPTR], &init)))
-		if len(init) != 0 {
-			base.Fatalf("race walk: unexpected init for getcallerpc")
-		}
-		fn.Exit.Append(mkcallstmt("racefuncexit"))
-		base.Pos = lno
-	}
-}

src/cmd/compile/internal/walk/walk.go

@@ -45,10 +45,6 @@ func Walk(fn *ir.Func) {
 		ir.DumpList(s, ir.CurFunc.Body)
 	}
 
-	if base.Flag.Cfg.Instrumenting {
-		instrument(fn)
-	}
-
 	// Eagerly compute sizes of all variables for SSA.
 	for _, n := range fn.Dcl {
 		types.CalcSize(n.Type())