From: Josh Bleecher Snyder <josharian@gmail.com>
Date: Wed, 22 Sep 2021 18:13:20 +0000 (-0700)
Subject: debug/gosym: add pcHeader parsing helpers
X-Git-Tag: go1.18beta1~1160
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=45134acbe645665e93cf1d399027d56b44f23299;p=gostls13.git

debug/gosym: add pcHeader parsing helpers

A subsequent change will duplicate most of case ver116.
Make it easier to read.

Change-Id: I3a93181c7f094b12715b8a618e9efef7a1438a27
Reviewed-on: https://go-review.googlesource.com/c/go/+/351909
Trust: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
---

diff --git a/src/debug/gosym/pclntab.go b/src/debug/gosym/pclntab.go
index a72f9847d7..555add67e3 100644
--- a/src/debug/gosym/pclntab.go
+++ b/src/debug/gosym/pclntab.go
@@ -225,21 +225,23 @@ func (t *LineTable) parsePclnTab() {
 	t.quantum = uint32(t.Data[6])
 	t.ptrsize = uint32(t.Data[7])
 
+	offset := func(word uint32) uint64 {
+		return t.uintptr(t.Data[8+word*t.ptrsize:])
+	}
+	data := func(word uint32) []byte {
+		return t.Data[offset(word):]
+	}
+
 	switch possibleVersion {
 	case ver116:
-		t.nfunctab = uint32(t.uintptr(t.Data[8:]))
-		t.nfiletab = uint32(t.uintptr(t.Data[8+t.ptrsize:]))
-		offset := t.uintptr(t.Data[8+2*t.ptrsize:])
-		t.funcnametab = t.Data[offset:]
-		offset = t.uintptr(t.Data[8+3*t.ptrsize:])
-		t.cutab = t.Data[offset:]
-		offset = t.uintptr(t.Data[8+4*t.ptrsize:])
-		t.filetab = t.Data[offset:]
-		offset = t.uintptr(t.Data[8+5*t.ptrsize:])
-		t.pctab = t.Data[offset:]
-		offset = t.uintptr(t.Data[8+6*t.ptrsize:])
-		t.funcdata = t.Data[offset:]
-		t.functab = t.Data[offset:]
+		t.nfunctab = uint32(offset(0))
+		t.nfiletab = uint32(offset(1))
+		t.funcnametab = data(2)
+		t.cutab = data(3)
+		t.filetab = data(4)
+		t.pctab = data(5)
+		t.funcdata = data(6)
+		t.functab = data(6)
 		functabsize := t.nfunctab*2*t.ptrsize + t.ptrsize
 		t.functab = t.functab[:functabsize]
 	case ver12: