liblink: create new library based on linker code

There is an enormous amount of code moving around in this CL,
but the code is the same, and it is invoked in the same ways.
This CL is preparation for the new linker structure, not the new
structure itself.

The new library's definition is in include/link.h.

The main change is the use of a Link structure to hold all the
linker-relevant state, replacing the smattering of global variables.
The Link structure should both make it clearer which state must
be carried around and make it possible to parallelize more easily
later.

The main body of the linker has moved into the architecture-independent
cmd/ld directory. That includes the list of known header types, so the
distinction between Hplan9x32 and Hplan9x64 is removed (no other
header type distinguished 32- and 64-bit formats), and code for unused
formats such as ipaq kernels has been deleted.

The code being deleted from 5l, 6l, and 8l reappears in liblink or in ld.
Because multiple files are being merged in the liblink directory,
it is not possible to show the diffs nicely in hg.

The Prog and Addr structures have been unified into an
architecture-independent form and moved to link.h, where they will
be shared by all tools: the assemblers, the compilers, and the linkers.
The unification makes it possible to write architecture-independent
traversal of Prog lists, among other benefits.

The Sym structures cannot be unified: they are too fundamentally
different between the linker and the compilers. Instead, liblink defines
an LSym - a linker Sym - to be used in the Prog and Addr structures,
and the linker now refers exclusively to LSyms. The compilers will
keep using their own syms but will fill out the corresponding LSyms in
the Prog and Addr structures.

Although code from 5l, 6l, and 8l is now in a single library, the
code has been arranged so that only one architecture needs to
be linked into a particular program: 5l will not contain the code
needed for x86 instruction layout, for example.

The object file writing code in liblink/obj.c is from cmd/gc/obj.c.

Preparation for golang.org/s/go13linker work.

This CL does not build by itself. It depends on 35740044
and will be submitted at the same time.

R=iant
CC=golang-dev
https://golang.org/cl/35790044

1 files changed, 403 insertions, 0 deletions

diff --git a/src/liblink/obj.c b/src/liblink/obj.c
new file mode 100644
index 0000000000..eacbc4011a
--- /dev/null
+++ b/src/liblink/obj.c
@@ -0,0 +1,403 @@
+// Copyright 2009 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.
+
+#include <u.h>
+#include <libc.h>
+#include <bio.h>
+#include <link.h>
+
+enum
+{
+	HISTSZ = 10,
+	NSYM = 50,
+};
+
+int
+linklinefmt(Link *ctxt, Fmt *fp)
+{
+	struct
+	{
+		Hist*	incl;	/* start of this include file */
+		int32	idel;	/* delta line number to apply to include */
+		Hist*	line;	/* start of this #line directive */
+		int32	ldel;	/* delta line number to apply to #line */
+	} a[HISTSZ];
+	int32 lno, d;
+	int i, n;
+	Hist *h;
+
+	lno = va_arg(fp->args, int32);
+
+	n = 0;
+	for(h=ctxt->hist; h!=nil; h=h->link) {
+		if(h->offset < 0)
+			continue;
+		if(lno < h->line)
+			break;
+		if(h->name) {
+			if(h->offset > 0) {
+				// #line directive
+				if(n > 0 && n < HISTSZ) {
+					a[n-1].line = h;
+					a[n-1].ldel = h->line - h->offset + 1;
+				}
+			} else {
+				// beginning of file
+				if(n < HISTSZ) {
+					a[n].incl = h;
+					a[n].idel = h->line;
+					a[n].line = 0;
+				}
+				n++;
+			}
+			continue;
+		}
+		n--;
+		if(n > 0 && n < HISTSZ) {
+			d = h->line - a[n].incl->line;
+			a[n-1].ldel += d;
+			a[n-1].idel += d;
+		}
+	}
+
+	if(n > HISTSZ)
+		n = HISTSZ;
+
+	for(i=n-1; i>=0; i--) {
+		if(i != n-1) {
+			if(fp->flags & ~(FmtWidth|FmtPrec))
+				break;
+			fmtprint(fp, " ");
+		}
+		if(ctxt->debugline || (fp->flags&FmtLong))
+			fmtprint(fp, "%s/", ctxt->pathname);
+		if(a[i].line)
+			fmtprint(fp, "%s:%d[%s:%d]",
+				a[i].line->name, lno-a[i].ldel+1,
+				a[i].incl->name, lno-a[i].idel+1);
+		else
+			fmtprint(fp, "%s:%d",
+				a[i].incl->name, lno-a[i].idel+1);
+		lno = a[i].incl->line - 1;	// now print out start of this file
+	}
+	if(n == 0)
+		fmtprint(fp, "<unknown line number>");
+
+	return 0;
+}
+
+static void
+outzfile(Link *ctxt, Biobuf *b, char *p)
+{
+	char *q, *q2;
+
+	while(p) {
+		q = utfrune(p, '/');
+		if(ctxt->windows) {
+			q2 = utfrune(p, '\\');
+			if(q2 && (!q || q2 < q))
+				q = q2;
+		}
+		if(!q) {
+			ctxt->arch->zfile(b, p, strlen(p));
+			return;
+		}
+		if(q > p)
+			ctxt->arch->zfile(b, p, q-p);
+		p = q + 1;
+	}
+}
+
+#define isdelim(c) (c == '/' || c == '\\')
+
+static void
+outwinname(Link *ctxt, Biobuf *b, Hist *h, char *ds, char *p)
+{
+	if(isdelim(p[0])) {
+		// full rooted name
+		ctxt->arch->zfile(b, ds, 3);	// leading "c:/"
+		outzfile(ctxt, b, p+1);
+	} else {
+		// relative name
+		if(h->offset >= 0 && ctxt->pathname && ctxt->pathname[1] == ':') {
+			if(tolowerrune(ds[0]) == tolowerrune(ctxt->pathname[0])) {
+				// using current drive
+				ctxt->arch->zfile(b, ctxt->pathname, 3);	// leading "c:/"
+				outzfile(ctxt, b, ctxt->pathname+3);
+			} else {
+				// using drive other then current,
+				// we don't have any simple way to
+				// determine current working directory
+				// there, therefore will output name as is
+				ctxt->arch->zfile(b, ds, 2);	// leading "c:"
+			}
+		}
+		outzfile(ctxt, b, p);
+	}
+}
+
+void
+linkouthist(Link *ctxt, Biobuf *b)
+{
+	Hist *h;
+	char *p, ds[] = {'c', ':', '/', 0};
+	char *tofree;
+	int n;
+	static int first = 1;
+	static char *goroot, *goroot_final;
+
+	if(first) {
+		// Decide whether we need to rewrite paths from $GOROOT to $GOROOT_FINAL.
+		first = 0;
+		goroot = getenv("GOROOT");
+		goroot_final = getenv("GOROOT_FINAL");
+		if(goroot == nil)
+			goroot = "";
+		if(goroot_final == nil)
+			goroot_final = goroot;
+		if(strcmp(goroot, goroot_final) == 0) {
+			goroot = nil;
+			goroot_final = nil;
+		}
+	}
+
+	tofree = nil;
+	for(h = ctxt->hist; h != nil; h = h->link) {
+		p = h->name;
+		if(p) {
+			if(goroot != nil) {
+				n = strlen(goroot);
+				if(strncmp(p, goroot, strlen(goroot)) == 0 && p[n] == '/') {
+					tofree = smprint("%s%s", goroot_final, p+n);
+					p = tofree;
+				}
+			}
+			if(ctxt->windows) {
+				// if windows variable is set, then, we know already,
+				// pathname is started with windows drive specifier
+				// and all '\' were replaced with '/' (see lex.c)
+				if(isdelim(p[0]) && isdelim(p[1])) {
+					// file name has network name in it, 
+					// like \\server\share\dir\file.go
+					ctxt->arch->zfile(b, "//", 2);	// leading "//"
+					outzfile(ctxt, b, p+2);
+				} else if(p[1] == ':') {
+					// file name has drive letter in it
+					ds[0] = p[0];
+					outwinname(ctxt, b, h, ds, p+2);
+				} else {
+					// no drive letter in file name
+					outwinname(ctxt, b, h, ctxt->pathname, p);
+				}
+			} else {
+				if(p[0] == '/') {
+					// full rooted name, like /home/rsc/dir/file.go
+					ctxt->arch->zfile(b, "/", 1);	// leading "/"
+					outzfile(ctxt, b, p+1);
+				} else {
+					// relative name, like dir/file.go
+					if(h->offset >= 0 && ctxt->pathname && ctxt->pathname[0] == '/') {
+						ctxt->arch->zfile(b, "/", 1);	// leading "/"
+						outzfile(ctxt, b, ctxt->pathname+1);
+					}
+					outzfile(ctxt, b, p);
+				}
+			}
+		}
+		ctxt->arch->zhist(b, h->line, h->offset);
+		if(tofree) {
+			free(tofree);
+			tofree = nil;
+		}
+	}
+}
+
+void
+linklinehist(Link *ctxt, int lineno, char *f, int offset)
+{
+	Hist *h;
+
+	if(0) // debug['f']
+		if(f) {
+			if(offset)
+				print("%4d: %s (#line %d)\n", lineno, f, offset);
+			else
+				print("%4d: %s\n", lineno, f);
+		} else
+			print("%4d: <pop>\n", lineno);
+
+	h = malloc(sizeof(Hist));
+	memset(h, 0, sizeof *h);
+	h->name = f;
+	h->line = lineno;
+	h->offset = offset;
+	h->link = nil;
+	if(ctxt->ehist == nil) {
+		ctxt->hist = h;
+		ctxt->ehist = h;
+		return;
+	}
+	ctxt->ehist->link = h;
+	ctxt->ehist = h;
+}
+
+void
+linkprfile(Link *ctxt, int32 l)
+{
+	int i, n;
+	Hist a[HISTSZ], *h;
+	int32 d;
+
+	n = 0;
+	for(h = ctxt->hist; h != nil; h = h->link) {
+		if(l < h->line)
+			break;
+		if(h->name) {
+			if(h->offset == 0) {
+				if(n >= 0 && n < HISTSZ)
+					a[n] = *h;
+				n++;
+				continue;
+			}
+			if(n > 0 && n < HISTSZ)
+				if(a[n-1].offset == 0) {
+					a[n] = *h;
+					n++;
+				} else
+					a[n-1] = *h;
+			continue;
+		}
+		n--;
+		if(n >= 0 && n < HISTSZ) {
+			d = h->line - a[n].line;
+			for(i=0; i<n; i++)
+				a[i].line += d;
+		}
+	}
+	if(n > HISTSZ)
+		n = HISTSZ;
+	for(i=0; i<n; i++)
+		print("%s:%ld ", a[i].name, (long)(l-a[i].line+a[i].offset+1));
+}
+
+/*
+ * start a new Prog list.
+ */
+Plist*
+linknewplist(Link *ctxt)
+{
+	Plist *pl;
+
+	pl = malloc(sizeof(*pl));
+	memset(pl, 0, sizeof *pl);
+	if(ctxt->plist == nil)
+		ctxt->plist = pl;
+	else
+		ctxt->plast->link = pl;
+	ctxt->plast = pl;
+
+	return pl;
+}
+
+static struct {
+	struct { LSym *sym; short type; } h[NSYM];
+	int sym;
+} z;
+
+static void
+zsymreset(void)
+{
+	for(z.sym=0; z.sym<NSYM; z.sym++) {
+		z.h[z.sym].sym = nil;
+		z.h[z.sym].type = 0;
+	}
+	z.sym = 1;
+}
+
+
+static int
+zsym(Link *ctxt, Biobuf *b, LSym *s, int t, int *new)
+{
+	int i;
+
+	*new = 0;
+	if(s == nil)
+		return 0;
+
+	i = s->symid;
+	if(i < 0 || i >= NSYM)
+		i = 0;
+	if(z.h[i].type == t && z.h[i].sym == s)
+		return i;
+	i = z.sym;
+	s->symid = i;
+	ctxt->arch->zname(b, s, t);
+	z.h[i].sym = s;
+	z.h[i].type = t;
+	if(++z.sym >= NSYM)
+		z.sym = 1;
+	*new = 1;
+	return i;
+}
+
+static int
+zsymaddr(Link *ctxt, Biobuf *b, Addr *a, int *new)
+{
+	return zsym(ctxt, b, a->sym, ctxt->arch->symtype(a), new);
+}
+
+void
+linkwritefuncs(Link *ctxt, Biobuf *b)
+{
+	int32 pcloc;
+	Plist *pl;
+	LSym *s;
+	Prog *p;
+	int sf, st, gf, gt, new;
+
+	zsymreset();
+
+	// fix up pc
+	pcloc = 0;
+	for(pl=ctxt->plist; pl!=nil; pl=pl->link) {
+		if(pl->name != nil && strcmp(pl->name->name, "_") == 0)
+			continue;
+		for(p=pl->firstpc; p!=nil; p=p->link) {
+			p->loc = pcloc;
+			if(!ctxt->arch->isdata(p))
+				pcloc++;
+		}
+	}
+
+	// put out functions
+	for(pl=ctxt->plist; pl!=nil; pl=pl->link) {
+		if(pl->name != nil && strcmp(pl->name->name, "_") == 0)
+			continue;
+
+		// -S prints code; -S -S prints code and data
+		if(ctxt->debugasm && (pl->name || ctxt->debugasm>1)) {
+			s = pl->name;
+			print("\n--- prog list \"%lS\" ---\n", s);
+			for(p=pl->firstpc; p!=nil; p=p->link)
+				print("%P\n", p);
+		}
+
+		for(p=pl->firstpc; p!=nil; p=p->link) {
+			for(;;) {
+				sf = zsymaddr(ctxt, b, &p->from, &new);
+				gf = zsym(ctxt, b, p->from.gotype, ctxt->arch->D_EXTERN, &new);
+				if(new && sf == gf)
+					continue;
+				st = zsymaddr(ctxt, b, &p->to, &new);
+				if(new && (st == sf || st == gf))
+					continue;
+				gt = zsym(ctxt, b, p->to.gotype, ctxt->arch->D_EXTERN, &new);
+				if(new && (gt == sf || gt == gf || gt == st))
+					continue;
+				break;
+			}
+			ctxt->arch->zprog(ctxt, b, p, sf, gf, st, gt);
+		}
+	}
+}