cmd/compile: reduce rulegen's output by 200 KiB

First, renove unnecessary "// cond:" lines from the generated files.
This shaves off about ~7k lines.

Second, join "if cond { break }" statements via "||", which allows us to
deduplicate a large number of them. This shaves off another ~25k lines.

This change is not for readability or simplicity; but rather, to avoid
unnecessary verbosity that makes the generated files larger. All in all,
git reports that the generated files overall weigh ~200KiB less, or
about 2.7% less.

While at it, add a -trace flag to rulegen.

Updates #33644.

Change-Id: I3fac0290a6066070cc62400bf970a4ae0929470a
Reviewed-on: https://go-review.googlesource.com/c/go/+/196498
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

src/cmd/compile/internal/ssa/gen/main.go

@@ -20,6 +20,7 @@ import (
 	"regexp"
 	"runtime"
 	"runtime/pprof"
+	"runtime/trace"
 	"sort"
 	"strings"
 	"sync"
@@ -101,6 +102,7 @@ var archs []arch
 
 var cpuprofile = flag.String("cpuprofile", "", "write cpu profile to `file`")
 var memprofile = flag.String("memprofile", "", "write memory profile to `file`")
+var tracefile = flag.String("trace", "", "write trace to `file`")
 
 func main() {
 	flag.Parse()
@@ -115,6 +117,23 @@ func main() {
 		}
 		defer pprof.StopCPUProfile()
 	}
+	if *tracefile != "" {
+		f, err := os.Create(*tracefile)
+		if err != nil {
+			log.Fatalf("failed to create trace output file: %v", err)
+		}
+		defer func() {
+			if err := f.Close(); err != nil {
+				log.Fatalf("failed to close trace file: %v", err)
+			}
+		}()
+
+		if err := trace.Start(f); err != nil {
+			log.Fatalf("failed to start trace: %v", err)
+		}
+		defer trace.Stop()
+	}
+
 	sort.Sort(ArchsByName(archs))
 
 	// The generate tasks are run concurrently, since they are CPU-intensive

src/cmd/compile/internal/ssa/gen/rulegen.go

@@ -587,7 +587,9 @@ func fprint(w io.Writer, n Node) {
 		}
 	case *RuleRewrite:
 		fmt.Fprintf(w, "// match: %s\n", n.match)
-		fmt.Fprintf(w, "// cond: %s\n", n.cond)
+		if n.cond != "" {
+			fmt.Fprintf(w, "// cond: %s\n", n.cond)
+		}
 		fmt.Fprintf(w, "// result: %s\n", n.result)
 		if n.checkOp != "" {
 			fmt.Fprintf(w, "for v.Op == %s {\n", n.checkOp)
@@ -636,13 +638,26 @@ type bodyBase struct {
 	canFail bool
 }
 
-func (w *bodyBase) add(nodes ...Statement) {
-	w.list = append(w.list, nodes...)
-	for _, node := range nodes {
-		if _, ok := node.(*CondBreak); ok {
-			w.canFail = true
+func (w *bodyBase) add(node Statement) {
+	var last Statement
+	if len(w.list) > 0 {
+		last = w.list[len(w.list)-1]
+	}
+	if node, ok := node.(*CondBreak); ok {
+		w.canFail = true
+		if last, ok := last.(*CondBreak); ok {
+			// Add to the previous "if <cond> { break }" via a
+			// logical OR, which will save verbosity.
+			last.expr = &ast.BinaryExpr{
+				Op: token.LOR,
+				X:  last.expr,
+				Y:  node.expr,
+			}
+			return
 		}
 	}
+
+	w.list = append(w.list, node)
 }
 
 // declared reports if the body contains a Declare with the given name.

src/cmd/compile/internal/ssa/rewrite386splitload.go

@@ -24,7 +24,6 @@ func rewriteValue386splitload_Op386CMPBconstload_0(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPBconstload {sym} [vo] ptr mem)
-	// cond:
 	// result: (CMPBconst (MOVBload {sym} [offOnly(vo)] ptr mem) [valOnly(vo)])
 	for {
 		vo := v.AuxInt
@@ -46,7 +45,6 @@ func rewriteValue386splitload_Op386CMPBload_0(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPBload {sym} [off] ptr x mem)
-	// cond:
 	// result: (CMPB (MOVBload {sym} [off] ptr mem) x)
 	for {
 		off := v.AuxInt
@@ -69,7 +67,6 @@ func rewriteValue386splitload_Op386CMPLconstload_0(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPLconstload {sym} [vo] ptr mem)
-	// cond:
 	// result: (CMPLconst (MOVLload {sym} [offOnly(vo)] ptr mem) [valOnly(vo)])
 	for {
 		vo := v.AuxInt
@@ -91,7 +88,6 @@ func rewriteValue386splitload_Op386CMPLload_0(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPLload {sym} [off] ptr x mem)
-	// cond:
 	// result: (CMPL (MOVLload {sym} [off] ptr mem) x)
 	for {
 		off := v.AuxInt
@@ -114,7 +110,6 @@ func rewriteValue386splitload_Op386CMPWconstload_0(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPWconstload {sym} [vo] ptr mem)
-	// cond:
 	// result: (CMPWconst (MOVWload {sym} [offOnly(vo)] ptr mem) [valOnly(vo)])
 	for {
 		vo := v.AuxInt
@@ -136,7 +131,6 @@ func rewriteValue386splitload_Op386CMPWload_0(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPWload {sym} [off] ptr x mem)
-	// cond:
 	// result: (CMPW (MOVWload {sym} [off] ptr mem) x)
 	for {
 		off := v.AuxInt

src/cmd/compile/internal/ssa/rewriteAMD64splitload.go

@@ -28,7 +28,6 @@ func rewriteValueAMD64splitload_OpAMD64CMPBconstload_0(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPBconstload {sym} [vo] ptr mem)
-	// cond:
 	// result: (CMPBconst (MOVBload {sym} [offOnly(vo)] ptr mem) [valOnly(vo)])
 	for {
 		vo := v.AuxInt
@@ -50,7 +49,6 @@ func rewriteValueAMD64splitload_OpAMD64CMPBload_0(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPBload {sym} [off] ptr x mem)
-	// cond:
 	// result: (CMPB (MOVBload {sym} [off] ptr mem) x)
 	for {
 		off := v.AuxInt
@@ -73,7 +71,6 @@ func rewriteValueAMD64splitload_OpAMD64CMPLconstload_0(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPLconstload {sym} [vo] ptr mem)
-	// cond:
 	// result: (CMPLconst (MOVLload {sym} [offOnly(vo)] ptr mem) [valOnly(vo)])
 	for {
 		vo := v.AuxInt
@@ -95,7 +92,6 @@ func rewriteValueAMD64splitload_OpAMD64CMPLload_0(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPLload {sym} [off] ptr x mem)
-	// cond:
 	// result: (CMPL (MOVLload {sym} [off] ptr mem) x)
 	for {
 		off := v.AuxInt
@@ -118,7 +114,6 @@ func rewriteValueAMD64splitload_OpAMD64CMPQconstload_0(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPQconstload {sym} [vo] ptr mem)
-	// cond:
 	// result: (CMPQconst (MOVQload {sym} [offOnly(vo)] ptr mem) [valOnly(vo)])
 	for {
 		vo := v.AuxInt
@@ -140,7 +135,6 @@ func rewriteValueAMD64splitload_OpAMD64CMPQload_0(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPQload {sym} [off] ptr x mem)
-	// cond:
 	// result: (CMPQ (MOVQload {sym} [off] ptr mem) x)
 	for {
 		off := v.AuxInt
@@ -163,7 +157,6 @@ func rewriteValueAMD64splitload_OpAMD64CMPWconstload_0(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPWconstload {sym} [vo] ptr mem)
-	// cond:
 	// result: (CMPWconst (MOVWload {sym} [offOnly(vo)] ptr mem) [valOnly(vo)])
 	for {
 		vo := v.AuxInt
@@ -185,7 +178,6 @@ func rewriteValueAMD64splitload_OpAMD64CMPWload_0(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPWload {sym} [off] ptr x mem)
-	// cond:
 	// result: (CMPW (MOVWload {sym} [off] ptr mem) x)
 	for {
 		off := v.AuxInt

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

@@ -34,7 +34,6 @@ func rewriteValuedec(v *Value) bool {
 }
 func rewriteValuedec_OpComplexImag_0(v *Value) bool {
 	// match: (ComplexImag (ComplexMake _ imag))
-	// cond:
 	// result: imag
 	for {
 		v_0 := v.Args[0]
@@ -51,7 +50,6 @@ func rewriteValuedec_OpComplexImag_0(v *Value) bool {
 }
 func rewriteValuedec_OpComplexReal_0(v *Value) bool {
 	// match: (ComplexReal (ComplexMake real _))
-	// cond:
 	// result: real
 	for {
 		v_0 := v.Args[0]
@@ -69,7 +67,6 @@ func rewriteValuedec_OpComplexReal_0(v *Value) bool {
 }
 func rewriteValuedec_OpIData_0(v *Value) bool {
 	// match: (IData (IMake _ data))
-	// cond:
 	// result: data
 	for {
 		v_0 := v.Args[0]
@@ -86,7 +83,6 @@ func rewriteValuedec_OpIData_0(v *Value) bool {
 }
 func rewriteValuedec_OpITab_0(v *Value) bool {
 	// match: (ITab (IMake itab _))
-	// cond:
 	// result: itab
 	for {
 		v_0 := v.Args[0]
@@ -237,7 +233,6 @@ func rewriteValuedec_OpLoad_0(v *Value) bool {
 }
 func rewriteValuedec_OpSliceCap_0(v *Value) bool {
 	// match: (SliceCap (SliceMake _ _ cap))
-	// cond:
 	// result: cap
 	for {
 		v_0 := v.Args[0]
@@ -254,7 +249,6 @@ func rewriteValuedec_OpSliceCap_0(v *Value) bool {
 }
 func rewriteValuedec_OpSliceLen_0(v *Value) bool {
 	// match: (SliceLen (SliceMake _ len _))
-	// cond:
 	// result: len
 	for {
 		v_0 := v.Args[0]
@@ -272,7 +266,6 @@ func rewriteValuedec_OpSliceLen_0(v *Value) bool {
 }
 func rewriteValuedec_OpSlicePtr_0(v *Value) bool {
 	// match: (SlicePtr (SliceMake ptr _ _))
-	// cond:
 	// result: ptr
 	for {
 		v_0 := v.Args[0]
@@ -355,7 +348,6 @@ func rewriteValuedec_OpStore_0(v *Value) bool {
 		return true
 	}
 	// match: (Store dst (StringMake ptr len) mem)
-	// cond:
 	// result: (Store {typ.Int} (OffPtr <typ.IntPtr> [config.PtrSize] dst) len (Store {typ.BytePtr} dst ptr mem))
 	for {
 		mem := v.Args[2]
@@ -382,7 +374,6 @@ func rewriteValuedec_OpStore_0(v *Value) bool {
 		return true
 	}
 	// match: (Store dst (SliceMake ptr len cap) mem)
-	// cond:
 	// result: (Store {typ.Int} (OffPtr <typ.IntPtr> [2*config.PtrSize] dst) cap (Store {typ.Int} (OffPtr <typ.IntPtr> [config.PtrSize] dst) len (Store {typ.BytePtr} dst ptr mem)))
 	for {
 		mem := v.Args[2]
@@ -418,7 +409,6 @@ func rewriteValuedec_OpStore_0(v *Value) bool {
 		return true
 	}
 	// match: (Store dst (IMake itab data) mem)
-	// cond:
 	// result: (Store {typ.BytePtr} (OffPtr <typ.BytePtrPtr> [config.PtrSize] dst) data (Store {typ.Uintptr} dst itab mem))
 	for {
 		mem := v.Args[2]
@@ -448,7 +438,6 @@ func rewriteValuedec_OpStore_0(v *Value) bool {
 }
 func rewriteValuedec_OpStringLen_0(v *Value) bool {
 	// match: (StringLen (StringMake _ len))
-	// cond:
 	// result: len
 	for {
 		v_0 := v.Args[0]
@@ -465,7 +454,6 @@ func rewriteValuedec_OpStringLen_0(v *Value) bool {
 }
 func rewriteValuedec_OpStringPtr_0(v *Value) bool {
 	// match: (StringPtr (StringMake ptr _))
-	// cond:
 	// result: ptr
 	for {
 		v_0 := v.Args[0]