gopls/internal/golang/assembly.go - tools - Git at Google

 // Copyright 2024 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 golang

 // This file produces the "Browse GOARCH assembly of f" HTML report.
 //
 // See also:
 // - ./codeaction.go - computes the symbol and offers the CodeAction command.
 // - ../server/command.go - handles the command by opening a web page.
 // - ../server/server.go - handles the HTTP request and calls this function.

 import (
 	"bytes"
 	"context"
 	"fmt"
 	"html"
 	"path/filepath"
 	"regexp"
 	"strconv"
 	"strings"

 	"golang.org/x/tools/gopls/internal/cache"
 	"golang.org/x/tools/internal/gocommand"
 )

 // AssemblyHTML returns an HTML document containing an assembly listing of the selected function.
 //
 // TODO(adonovan):
 // - display a "Compiling..." message as a cold build can be slow.
 // - cross-link jumps and block labels, like github.com/aclements/objbrowse.
 func AssemblyHTML(ctx context.Context, snapshot *cache.Snapshot, pkg *cache.Package, symbol string, web Web) ([]byte, error) {
 	// Compile the package with -S, and capture its stderr stream.
 	inv, cleanupInvocation, err := snapshot.GoCommandInvocation(false, &gocommand.Invocation{
 		Verb:       "build",
 		Args:       []string{"-gcflags=-S", "."},
 		WorkingDir: filepath.Dir(pkg.Metadata().CompiledGoFiles[0].Path()),
 	})
 	if err != nil {
 		return nil, err // e.g. failed to write overlays (rare)
 	}
 	defer cleanupInvocation()
 	_, stderr, err, _ := snapshot.View().GoCommandRunner().RunRaw(ctx, *inv)
 	if err != nil {
 		return nil, err // e.g. won't compile
 	}
 	content := stderr.String()

 	escape := html.EscapeString

 	// Produce the report.
 	title := fmt.Sprintf("%s assembly for %s",
 		escape(snapshot.View().GOARCH()),
 		escape(symbol))
 	var buf bytes.Buffer
 	buf.WriteString(`<!DOCTYPE html>
 <html>
 <head>
   <meta charset="UTF-8">
   <title>` + escape(title) + `</title>
   <link rel="stylesheet" href="/assets/common.css">
   <script src="/assets/common.js"></script>
 </head>
 <body>
 <h1>` + title + `</h1>
 <p>
   <a href='https://go.dev/doc/asm'>A Quick Guide to Go's Assembler</a>
 </p>
 <p>
   Experimental. <a href='https://github.com/golang/go/issues/67478'>Contributions welcome!</a>
 </p>
 <p>
   Click on a source line marker <code>L1234</code> to navigate your editor there.
   (VS Code users: please upvote <a href='https://github.com/microsoft/vscode/issues/208093'>#208093</a>)
 </p>
 <p>
   Reload the page to recompile.
 </p>
 <pre>
 `)

 	// insnRx matches an assembly instruction line.
 	// Submatch groups are: (offset-hex-dec, file-line-column, instruction).
 	insnRx := regexp.MustCompile(`^(\s+0x[0-9a-f ]+)\(([^)]*)\)\s+(.*)$`)

 	// Parse the functions of interest out of the listing.
 	// Each function is of the form:
 	//
 	//     symbol STEXT k=v...
 	//         0x0000 00000 (/file.go:123) NOP...
 	//         ...
 	//
 	// Allow matches of symbol, symbol.func1, symbol.deferwrap, etc.
 	on := false
 	for _, line := range strings.Split(content, "\n") {
 		// start of function symbol?
 		if strings.Contains(line, " STEXT ") {
 			on = strings.HasPrefix(line, symbol) &&
 				(line[len(symbol)] == ' ' || line[len(symbol)] == '.')
 		}
 		if !on {
 			continue // within uninteresting symbol
 		}

 		// In lines of the form
 		//   "\t0x0000 00000 (/file.go:123) NOP..."
 		// replace the "(/file.go:123)" portion with an "L0123" source link.
 		// Skip filenames of the form "<foo>".
 		if parts := insnRx.FindStringSubmatch(line); parts != nil {
 			link := "     " // if unknown
 			if file, linenum, ok := cutLast(parts[2], ":"); ok && !strings.HasPrefix(file, "<") {
 				if linenum, err := strconv.Atoi(linenum); err == nil {
 					text := fmt.Sprintf("L%04d", linenum)
 					link = sourceLink(text, web.SrcURL(file, linenum, 1))
 				}
 			}
 			fmt.Fprintf(&buf, "%s\t%s\t%s", escape(parts[1]), link, escape(parts[3]))
 		} else {
 			buf.WriteString(escape(line))
 		}
 		buf.WriteByte('\n')
 	}
 	return buf.Bytes(), nil
 }

 // cutLast is the "last" analogue of [strings.Cut].
 func cutLast(s, sep string) (before, after string, ok bool) {
 	if i := strings.LastIndex(s, sep); i >= 0 {
 		return s[:i], s[i+len(sep):], true
 	}
 	return s, "", false
 }
	// Copyright 2024 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 golang

	// This file produces the "Browse GOARCH assembly of f" HTML report.
	//
	// See also:
	// - ./codeaction.go - computes the symbol and offers the CodeAction command.
	// - ../server/command.go - handles the command by opening a web page.
	// - ../server/server.go - handles the HTTP request and calls this function.

	import (
	"bytes"
	"context"
	"fmt"
	"html"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/internal/gocommand"
	)

	// AssemblyHTML returns an HTML document containing an assembly listing of the selected function.
	//
	// TODO(adonovan):
	// - display a "Compiling..." message as a cold build can be slow.
	// - cross-link jumps and block labels, like github.com/aclements/objbrowse.
	func AssemblyHTML(ctx context.Context, snapshot cache.Snapshot, pkg cache.Package, symbol string, web Web) ([]byte, error) {
	// Compile the package with -S, and capture its stderr stream.
	inv, cleanupInvocation, err := snapshot.GoCommandInvocation(false, &gocommand.Invocation{
	Verb: "build",
	Args: []string{"-gcflags=-S", "."},
	WorkingDir: filepath.Dir(pkg.Metadata().CompiledGoFiles[0].Path()),
	})
	if err != nil {
	return nil, err // e.g. failed to write overlays (rare)
	}
	defer cleanupInvocation()
	_, stderr, err, _ := snapshot.View().GoCommandRunner().RunRaw(ctx, *inv)
	if err != nil {
	return nil, err // e.g. won't compile
	}
	content := stderr.String()

	escape := html.EscapeString

	// Produce the report.
	title := fmt.Sprintf("%s assembly for %s",
	escape(snapshot.View().GOARCH()),
	escape(symbol))
	var buf bytes.Buffer
	buf.WriteString(`<!DOCTYPE html>
	<html>
	<head>
	<meta charset="UTF-8">
	<title>` + escape(title) + `</title>
	<link rel="stylesheet" href="/assets/common.css">
	<script src="/assets/common.js"></script>
	</head>
	<body>
	<h1>` + title + `</h1>
	<p>
	<a href='https://go.dev/doc/asm'>A Quick Guide to Go's Assembler</a>
	</p>
	<p>
	Experimental. <a href='https://github.com/golang/go/issues/67478'>Contributions welcome!</a>
	</p>
	<p>
	Click on a source line marker <code>L1234</code> to navigate your editor there.
	(VS Code users: please upvote <a href='https://github.com/microsoft/vscode/issues/208093'>#208093</a>)
	</p>
	<p>
	Reload the page to recompile.
	</p>
	<pre>
	`)

	// insnRx matches an assembly instruction line.
	// Submatch groups are: (offset-hex-dec, file-line-column, instruction).
	insnRx := regexp.MustCompile(`^(\s+0x[0-9a-f ]+)\(([^)])\)\s+(.)$`)

	// Parse the functions of interest out of the listing.
	// Each function is of the form:
	//
	// symbol STEXT k=v...
	// 0x0000 00000 (/file.go:123) NOP...
	// ...
	//
	// Allow matches of symbol, symbol.func1, symbol.deferwrap, etc.
	on := false
	for _, line := range strings.Split(content, "\n") {
	// start of function symbol?
	if strings.Contains(line, " STEXT ") {
	on = strings.HasPrefix(line, symbol) &&
	(line[len(symbol)] == ' ' \|\| line[len(symbol)] == '.')
	}
	if !on {
	continue // within uninteresting symbol
	}

	// In lines of the form
	// "\t0x0000 00000 (/file.go:123) NOP..."
	// replace the "(/file.go:123)" portion with an "L0123" source link.
	// Skip filenames of the form "<foo>".
	if parts := insnRx.FindStringSubmatch(line); parts != nil {
	link := " " // if unknown
	if file, linenum, ok := cutLast(parts[2], ":"); ok && !strings.HasPrefix(file, "<") {
	if linenum, err := strconv.Atoi(linenum); err == nil {
	text := fmt.Sprintf("L%04d", linenum)
	link = sourceLink(text, web.SrcURL(file, linenum, 1))
	}
	}
	fmt.Fprintf(&buf, "%s\t%s\t%s", escape(parts[1]), link, escape(parts[3]))
	} else {
	buf.WriteString(escape(line))
	}
	buf.WriteByte('\n')
	}
	return buf.Bytes(), nil
	}

	// cutLast is the "last" analogue of [strings.Cut].
	func cutLast(s, sep string) (before, after string, ok bool) {
	if i := strings.LastIndex(s, sep); i >= 0 {
	return s[:i], s[i+len(sep):], true
	}
	return s, "", false
	}