cmd/compile: display AST IR in ssa.html

This change adds a new column, AST IR. That column contains
nodes for a function specified in $GOSSAFUNC.

Also this CL enables horizontal scrolling of sources and AST columns.

Fixes #26662

Change-Id: I3fba39fd998bb05e9c93038e8ec2384c69613b24
Reviewed-on: https://go-review.googlesource.com/126858
Run-TryBot: Yury Smolsky <yury@smolsky.by>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

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

@@ -7,6 +7,7 @@ package gc
 import (
 	"cmd/compile/internal/types"
 	"fmt"
+	"io"
 	"strconv"
 	"strings"
 	"unicode/utf8"
@@ -1836,6 +1837,10 @@ func dumplist(s string, l Nodes) {
 	fmt.Printf("%s%+v\n", s, l)
 }
 
+func fdumplist(w io.Writer, s string, l Nodes) {
+	fmt.Fprintf(w, "%s%+v\n", s, l)
+}
+
 func Dump(s string, n *Node) {
 	fmt.Printf("%s [%p]%+v\n", s, n, n)
 }

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

@@ -111,11 +111,16 @@ func initssaconfig() {
 func buildssa(fn *Node, worker int) *ssa.Func {
 	name := fn.funcname()
 	printssa := name == ssaDump
+	var astBuf *bytes.Buffer
 	if printssa {
-		fmt.Println("generating SSA for", name)
-		dumplist("buildssa-enter", fn.Func.Enter)
-		dumplist("buildssa-body", fn.Nbody)
-		dumplist("buildssa-exit", fn.Func.Exit)
+		astBuf = &bytes.Buffer{}
+		fdumplist(astBuf, "buildssa-enter", fn.Func.Enter)
+		fdumplist(astBuf, "buildssa-body", fn.Nbody)
+		fdumplist(astBuf, "buildssa-exit", fn.Func.Exit)
+		if ssaDumpStdout {
+			fmt.Println("generating SSA for", name)
+			fmt.Print(astBuf.String())
+		}
 	}
 
 	var s state
@@ -151,6 +156,7 @@ func buildssa(fn *Node, worker int) *ssa.Func {
 		s.f.HTMLWriter = ssa.NewHTMLWriter(ssaDumpFile, s.f.Frontend(), name)
 		// TODO: generate and print a mapping from nodes to values and blocks
 		dumpSourcesColumn(s.f.HTMLWriter, fn)
+		s.f.HTMLWriter.WriteAST("AST", astBuf)
 	}
 
 	// Allocate starting block

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

@@ -12,6 +12,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"strconv"
 	"strings"
 )
 
@@ -103,11 +104,15 @@ td.collapsed  div {
          text-align: right;
 }
 
-code, pre, .lines {
+code, pre, .lines, .ast {
     font-family: Menlo, monospace;
     font-size: 12px;
 }
 
+.allow-x-scroll {
+    overflow-x: scroll;
+}
+
 .lines {
     float: left;
     overflow: hidden;
@@ -123,6 +128,10 @@ div.line-number {
     font-size: 12px;
 }
 
+.ast {
+    white-space: nowrap;
+}
+
 td.ssa-prog {
     width: 600px;
     word-wrap: break-word;
@@ -521,7 +530,49 @@ func (w *HTMLWriter) WriteSources(phase string, all []*FuncLines) {
 		}
 	}
 	fmt.Fprint(&buf, "</pre></div>")
-	w.WriteColumn(phase, phase, "", buf.String())
+	w.WriteColumn(phase, phase, "allow-x-scroll", buf.String())
+}
+
+func (w *HTMLWriter) WriteAST(phase string, buf *bytes.Buffer) {
+	if w == nil {
+		return // avoid generating HTML just to discard it
+	}
+	lines := strings.Split(buf.String(), "\n")
+	var out bytes.Buffer
+
+	fmt.Fprint(&out, "<div>")
+	for _, l := range lines {
+		l = strings.TrimSpace(l)
+		var escaped string
+		var lineNo string
+		if l == "" {
+			escaped = "&nbsp;"
+		} else {
+			if strings.HasPrefix(l, "buildssa") {
+				escaped = fmt.Sprintf("<b>%v</b>", l)
+			} else {
+				// Parse the line number from the format l(123).
+				idx := strings.Index(l, " l(")
+				if idx != -1 {
+					subl := l[idx+3:]
+					idxEnd := strings.Index(subl, ")")
+					if idxEnd != -1 {
+						if _, err := strconv.Atoi(subl[:idxEnd]); err == nil {
+							lineNo = subl[:idxEnd]
+						}
+					}
+				}
+				escaped = html.EscapeString(l)
+			}
+		}
+		if lineNo != "" {
+			fmt.Fprintf(&out, "<div class=\"l%v line-number ast\">%v</div>", lineNo, escaped)
+		} else {
+			fmt.Fprintf(&out, "<div class=\"ast\">%v</div>", escaped)
+		}
+	}
+	fmt.Fprint(&out, "</div>")
+	w.WriteColumn(phase, phase, "allow-x-scroll", out.String())
 }
 
 // WriteColumn writes raw HTML in a column headed by title.