[dev.ssa] cmd/compile: move rewrite logging behind codegen flag

Generating logging code every time causes large
diffs for small changes.

Since the intent is to use this for debugging only,
generate logging code only when requested.
Committed generated code will be logging free.

Change-Id: I9ef9e29c88b76c2557bad4c6b424b9db1255ec8b
Reviewed-on: https://go-review.googlesource.com/13623
Reviewed-by: Keith Randall <khr@golang.org>

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

@@ -9,6 +9,7 @@ package main
 
 import (
 	"bytes"
+	"flag"
 	"fmt"
 	"go/format"
 	"io/ioutil"
@@ -59,6 +60,7 @@ func (a arch) regMaskComment(r regMask) string {
 var archs []arch
 
 func main() {
+	flag.Parse()
 	genOp()
 	genLower()
 }

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

@@ -13,6 +13,7 @@ import (
 	"bufio"
 	"bytes"
 	"crypto/md5"
+	"flag"
 	"fmt"
 	"go/format"
 	"io"
@@ -45,6 +46,10 @@ import (
 
 // If multiple rules match, the first one in file order is selected.
 
+var (
+	genLog = flag.Bool("log", false, "generate code that logs; for debugging only")
+)
+
 type Rule struct {
 	rule   string
 	lineno int
@@ -134,7 +139,9 @@ func genRules(arch arch) {
 	fmt.Fprintf(w, "// autogenerated from gen/%s.rules: do not edit!\n", arch.name)
 	fmt.Fprintln(w, "// generated with: cd gen; go run *.go")
 	fmt.Fprintln(w, "package ssa")
-	fmt.Fprintln(w, "import \"fmt\"")
+	if *genLog {
+		fmt.Fprintln(w, "import \"fmt\"")
+	}
 	fmt.Fprintf(w, "func rewriteValue%s(v *Value, config *Config) bool {\n", arch.name)
 	fmt.Fprintln(w, "b := v.Block")
 
@@ -169,9 +176,9 @@ func genRules(arch arch) {
 			}
 
 			genResult(w, arch, result)
-			fmt.Fprintf(w, "if logRewriteRules {\n")
-			fmt.Fprintf(w, "  fmt.Println(\"rewrite %s.rules:%d\")", arch.name, rule.lineno)
-			fmt.Fprintf(w, "}\n")
+			if *genLog {
+				fmt.Fprintf(w, "fmt.Println(\"rewrite %s.rules:%d\")\n", arch.name, rule.lineno)
+			}
 			fmt.Fprintf(w, "return true\n")
 
 			fmt.Fprintf(w, "}\n")
@@ -275,9 +282,9 @@ func genRules(arch arch) {
 				fmt.Fprintln(w, "b.Likely = BranchUnknown")
 			}
 
-			fmt.Fprintf(w, "if logRewriteRules {\n")
-			fmt.Fprintf(w, "  fmt.Println(\"rewrite %s.rules:%d\")", arch.name, rule.lineno)
-			fmt.Fprintf(w, "}\n")
+			if *genLog {
+				fmt.Fprintf(w, "fmt.Println(\"rewrite %s.rules:%d\")\n", arch.name, rule.lineno)
+			}
 			fmt.Fprintf(w, "return true\n")
 
 			fmt.Fprintf(w, "}\n")
@@ -291,13 +298,14 @@ func genRules(arch arch) {
 
 	// gofmt result
 	b := w.Bytes()
-	b, err = format.Source(b)
+	src, err := format.Source(b)
 	if err != nil {
+		fmt.Printf("%s\n", b)
 		panic(err)
 	}
 
 	// Write to file
-	err = ioutil.WriteFile("../rewrite"+arch.name+".go", b, 0666)
+	err = ioutil.WriteFile("../rewrite"+arch.name+".go", src, 0666)
 	if err != nil {
 		log.Fatalf("can't write output: %v\n", err)
 	}

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

@@ -6,11 +6,6 @@ package ssa
 
 import "fmt"
 
-// Set to true to log all rewrite rules as they occur.
-// This is useful for figuring out whether a rule is triggering
-// and which rules are most heavily used.
-const logRewriteRules = false
-
 func applyRewrite(f *Func, rb func(*Block) bool, rv func(*Value, *Config) bool) {
 	// repeat rewrites until we find no more rewrites
 	var curb *Block

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

@@ -2,8 +2,6 @@
 // generated with: cd gen; go run *.go
 package ssa
 
-import "fmt"
-
 func rewriteValuegeneric(v *Value, config *Config) bool {
 	b := v.Block
 	switch v.Op {
@@ -25,9 +23,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.Aux = nil
 			v.resetArgs()
 			v.AuxInt = c + d
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:23")
-			}
 			return true
 		}
 		goto end8c46df6f85a11cb1d594076b0e467908
@@ -51,9 +46,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.Aux = nil
 			v.resetArgs()
 			v.AuxInt = c + d
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:24")
-			}
 			return true
 		}
 		goto end145c1aec793b2befff34bc8983b48a38
@@ -80,9 +72,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v0.AddArg(idx)
 			v.AddArg(v0)
 			v.AddArg(mem)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:59")
-			}
 			return true
 		}
 		goto end4894dd7b58383fee5f8a92be08437c33
@@ -103,9 +92,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.resetArgs()
 			v.Type = x.Type
 			v.AddArg(x)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:38")
-			}
 			return true
 		}
 		goto end1ea17710dd4dd7ba4e710e0e4c7b5a56
@@ -126,9 +112,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.resetArgs()
 			v.Type = x.Type
 			v.AddArg(x)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:39")
-			}
 			return true
 		}
 		goto end9a04ed536496e292c27bef4414128cbf
@@ -149,9 +132,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.resetArgs()
 			v.Type = x.Type
 			v.AddArg(x)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:40")
-			}
 			return true
 		}
 		goto ended44e29d5968f0f7b86972b7bf417ab3
@@ -172,9 +152,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.resetArgs()
 			v.Type = x.Type
 			v.AddArg(x)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:37")
-			}
 			return true
 		}
 		goto end4d92ff3ba567d9afd38fc9ca113602ad
@@ -201,9 +178,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v2.Type = config.Frontend().TypeUintptr()
 			v2.AuxInt = int64(len(s.(string)))
 			v.AddArg(v2)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:68")
-			}
 			return true
 		}
 		goto end68cc91679848c7c30bd8b0a8ed533843
@@ -223,9 +197,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.Aux = nil
 			v.resetArgs()
 			v.Aux = true
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:30")
-			}
 			return true
 		}
 		goto enda503589f9b617e708a5ad3ddb047809f
@@ -245,9 +216,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.Aux = nil
 			v.resetArgs()
 			v.Aux = true
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:29")
-			}
 			return true
 		}
 		goto endc94ae3b97d0090257b02152e437b3e17
@@ -267,9 +235,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.Aux = nil
 			v.resetArgs()
 			v.Aux = true
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:28")
-			}
 			return true
 		}
 		goto end4d21cead60174989467a9c8202dbb91d
@@ -289,9 +254,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.Aux = nil
 			v.resetArgs()
 			v.Aux = true
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:31")
-			}
 			return true
 		}
 		goto end73dce8bba164e4f4a1dd701bf8cfb362
@@ -313,9 +275,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.resetArgs()
 			v.AddArg(y)
 			v.AddArg(x)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:51")
-			}
 			return true
 		}
 		goto endcea7f7399afcff860c54d82230a9a934
@@ -346,9 +305,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v1.Type = config.Frontend().TypeUintptr()
 			v1.AuxInt = 0
 			v.AddArg(v1)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:54")
-			}
 			return true
 		}
 		goto end540dc8dfbc66adcd3db2d7e819c534f6
@@ -372,9 +328,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.Aux = nil
 			v.resetArgs()
 			v.Aux = inBounds(c, d)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:27")
-			}
 			return true
 		}
 		goto enddfd340bc7103ca323354aec96b113c23
@@ -409,9 +362,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v1.AddArg(v2)
 			v1.AddArg(mem)
 			v.AddArg(v1)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:69")
-			}
 			return true
 		}
 		goto end18afa4a6fdd6d0b92ed292840898c8f6
@@ -435,9 +385,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.Aux = nil
 			v.resetArgs()
 			v.AuxInt = c * d
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:25")
-			}
 			return true
 		}
 		goto end7aea1048b5d1230974b97f17238380ae
@@ -461,9 +408,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.Aux = nil
 			v.resetArgs()
 			v.AuxInt = c * d
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:26")
-			}
 			return true
 		}
 		goto end808c190f346658bb1ad032bf37a1059f
@@ -483,9 +427,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.Aux = nil
 			v.resetArgs()
 			v.Aux = false
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:34")
-			}
 			return true
 		}
 		goto end192755dd3c2be992e9d3deb53794a8d2
@@ -505,9 +446,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.Aux = nil
 			v.resetArgs()
 			v.Aux = false
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:33")
-			}
 			return true
 		}
 		goto endeb23619fc85950a8df7b31126252c4dd
@@ -527,9 +465,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.Aux = nil
 			v.resetArgs()
 			v.Aux = false
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:32")
-			}
 			return true
 		}
 		goto endfc6eea780fb4056afb9e4287076da60c
@@ -549,9 +484,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.Aux = nil
 			v.resetArgs()
 			v.Aux = false
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:35")
-			}
 			return true
 		}
 		goto endcccf700d93c6d57765b80f92f7b3fa81
@@ -573,9 +505,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.resetArgs()
 			v.AddArg(y)
 			v.AddArg(x)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:52")
-			}
 			return true
 		}
 		goto end94c68f7dc30c66ed42e507e01c4e5dc7
@@ -606,9 +535,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v1.Type = config.Frontend().TypeUintptr()
 			v1.AuxInt = 0
 			v.AddArg(v1)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:55")
-			}
 			return true
 		}
 		goto end67d723bb0f39a5c897816abcf411e5cf
@@ -635,9 +561,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v1.AuxInt = t.Elem().Size()
 			v0.AddArg(v1)
 			v.AddArg(v0)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:60")
-			}
 			return true
 		}
 		goto endf7546737f42c76a99699f241d41f491a
@@ -666,9 +589,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v0.AddArg(v1)
 			v.AddArg(v0)
 			v.AddArg(mem)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:46")
-			}
 			return true
 		}
 		goto end6696811bf6bd45e505d24c1a15c68e70
@@ -697,9 +617,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v0.AddArg(v1)
 			v.AddArg(v0)
 			v.AddArg(mem)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:45")
-			}
 			return true
 		}
 		goto end9844ce3e290e81355493141e653e37d5
@@ -721,9 +638,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.resetArgs()
 			v.AddArg(ptr)
 			v.AddArg(mem)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:44")
-			}
 			return true
 		}
 		goto end459613b83f95b65729d45c2ed663a153
@@ -755,9 +669,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.AddArg(dst)
 			v.AddArg(src)
 			v.AddArg(mem)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:65")
-			}
 			return true
 		}
 		goto end324ffb6d2771808da4267f62c854e9c8
@@ -795,9 +706,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v2.AddArg(v3)
 			v2.AddArg(mem)
 			v.AddArg(v2)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:72")
-			}
 			return true
 		}
 		goto enddf0c5a150f4b4bf6715fd2bd4bb4cc20
@@ -818,9 +726,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.resetArgs()
 			v.Type = len.Type
 			v.AddArg(len)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:71")
-			}
 			return true
 		}
 		goto end0d922460b7e5ca88324034f4bd6c027c
@@ -841,9 +746,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v.resetArgs()
 			v.Type = ptr.Type
 			v.AddArg(ptr)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:70")
-			}
 			return true
 		}
 		goto end061edc5d85c73ad909089af2556d9380
@@ -870,9 +772,6 @@ func rewriteValuegeneric(v *Value, config *Config) bool {
 			v0.AddArg(ptr)
 			v.AddArg(v0)
 			v.AddArg(mem)
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:61")
-			}
 			return true
 		}
 		goto end16fdb45e1dd08feb36e3cc3fb5ed8935
@@ -902,9 +801,6 @@ func rewriteBlockgeneric(b *Block) bool {
 			b.Succs = b.Succs[:1]
 			b.Succs[0] = yes
 			b.Likely = BranchUnknown
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:74")
-			}
 			return true
 		}
 		goto end0f2bb0111a86be0436b44210dbd83a90
@@ -926,9 +822,6 @@ func rewriteBlockgeneric(b *Block) bool {
 			b.Succs[0] = no
 			b.Succs[1] = yes
 			b.Likely *= -1
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:76")
-			}
 			return true
 		}
 		goto endebe19c1c3c3bec068cdb2dd29ef57f96
@@ -954,9 +847,6 @@ func rewriteBlockgeneric(b *Block) bool {
 			b.Succs = b.Succs[:1]
 			b.Succs[0] = yes
 			b.Likely = BranchUnknown
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:77")
-			}
 			return true
 		}
 		goto end9ff0273f9b1657f4afc287562ca889f0
@@ -982,9 +872,6 @@ func rewriteBlockgeneric(b *Block) bool {
 			b.Succs = b.Succs[:1]
 			b.Succs[0] = no
 			b.Likely = BranchUnknown
-			if logRewriteRules {
-				fmt.Println("rewrite generic.rules:78")
-			}
 			return true
 		}
 		goto endf401a4553c3c7c6bed64801da7bba076