src/liblink/pcln.c - go - Git at Google

 // Copyright 2013 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>

 static void
 addvarint(Link *ctxt, Pcdata *d, uint32 val)
 {
 	int32 n;
 	uint32 v;
 	uchar *p;

 	USED(ctxt);

 	n = 0;
 	for(v = val; v >= 0x80; v >>= 7)
 		n++;
 	n++;

 	if(d->n + n > d->m) {
 		d->m = (d->n + n)*2;
 		d->p = erealloc(d->p, d->m);
 	}

 	p = d->p + d->n;
 	for(v = val; v >= 0x80; v >>= 7)
 		*p++ = v | 0x80;
 	*p = v;
 	d->n += n;
 }

 // funcpctab writes to dst a pc-value table mapping the code in func to the values
 // returned by valfunc parameterized by arg. The invocation of valfunc to update the
 // current value is, for each p,
 //
 //	val = valfunc(func, val, p, 0, arg);
 //	record val as value at p->pc;
 //	val = valfunc(func, val, p, 1, arg);
 //
 // where func is the function, val is the current value, p is the instruction being
 // considered, and arg can be used to further parameterize valfunc.
 static void
 funcpctab(Link *ctxt, Pcdata *dst, LSym *func, char *desc, int32 (*valfunc)(Link*, LSym*, int32, Prog*, int32, void*), void* arg)
 {
 	int dbg, i;
 	int32 oldval, val, started;
 	uint32 delta;
 	vlong pc;
 	Prog *p;

 	// To debug a specific function, uncomment second line and change name.
 	dbg = 0;
 	//dbg = strcmp(func->name, "main.main") == 0;
 	//dbg = strcmp(desc, "pctofile") == 0;

 	ctxt->debugpcln += dbg;

 	dst->n = 0;

 	if(ctxt->debugpcln)
 		Bprint(ctxt->bso, "funcpctab %s [valfunc=%s]\n", func->name, desc);

 	val = -1;
 	oldval = val;
 	if(func->text == nil) {
 		ctxt->debugpcln -= dbg;
 		return;
 	}

 	pc = func->text->pc;

 	if(ctxt->debugpcln)
 		Bprint(ctxt->bso, "%6llux %6d %P\n", pc, val, func->text);

 	started = 0;
 	for(p=func->text; p != nil; p = p->link) {
 		// Update val. If it's not changing, keep going.
 		val = valfunc(ctxt, func, val, p, 0, arg);
 		if(val == oldval && started) {
 			val = valfunc(ctxt, func, val, p, 1, arg);
 			if(ctxt->debugpcln)
 				Bprint(ctxt->bso, "%6llux %6s %P\n", (vlong)p->pc, "", p);
 			continue;
 		}

 		// If the pc of the next instruction is the same as the
 		// pc of this instruction, this instruction is not a real
 		// instruction. Keep going, so that we only emit a delta
 		// for a true instruction boundary in the program.
 		if(p->link && p->link->pc == p->pc) {
 			val = valfunc(ctxt, func, val, p, 1, arg);
 			if(ctxt->debugpcln)
 				Bprint(ctxt->bso, "%6llux %6s %P\n", (vlong)p->pc, "", p);
 			continue;
 		}

 		// The table is a sequence of (value, pc) pairs, where each
 		// pair states that the given value is in effect from the current position
 		// up to the given pc, which becomes the new current position.
 		// To generate the table as we scan over the program instructions,
 		// we emit a "(value" when pc == func->value, and then
 		// each time we observe a change in value we emit ", pc) (value".
 		// When the scan is over, we emit the closing ", pc)".
 		//
 		// The table is delta-encoded. The value deltas are signed and
 		// transmitted in zig-zag form, where a complement bit is placed in bit 0,
 		// and the pc deltas are unsigned. Both kinds of deltas are sent
 		// as variable-length little-endian base-128 integers,
 		// where the 0x80 bit indicates that the integer continues.

 		if(ctxt->debugpcln)
 			Bprint(ctxt->bso, "%6llux %6d %P\n", (vlong)p->pc, val, p);

 		if(started) {
 			addvarint(ctxt, dst, (p->pc - pc) / ctxt->arch->minlc);
 			pc = p->pc;
 		}
 		delta = val - oldval;
 		if(delta>>31)
 			delta = 1 | ~(delta<<1);
 		else
 			delta <<= 1;
 		addvarint(ctxt, dst, delta);
 		oldval = val;
 		started = 1;
 		val = valfunc(ctxt, func, val, p, 1, arg);
 	}

 	if(started) {
 		if(ctxt->debugpcln)
 			Bprint(ctxt->bso, "%6llux done\n", (vlong)func->text->pc+func->size);
 		addvarint(ctxt, dst, (func->value+func->size - pc) / ctxt->arch->minlc);
 		addvarint(ctxt, dst, 0); // terminator
 	}

 	if(ctxt->debugpcln) {
 		Bprint(ctxt->bso, "wrote %d bytes to %p\n", dst->n, dst);
 		for(i=0; i<dst->n; i++)
 			Bprint(ctxt->bso, " %02ux", dst->p[i]);
 		Bprint(ctxt->bso, "\n");
 	}

 	ctxt->debugpcln -= dbg;
 }

 // pctofileline computes either the file number (arg == 0)
 // or the line number (arg == 1) to use at p.
 // Because p->lineno applies to p, phase == 0 (before p)
 // takes care of the update.
 static int32
 pctofileline(Link *ctxt, LSym *sym, int32 oldval, Prog *p, int32 phase, void *arg)
 {
 	int32 i, l;
 	LSym *f;
 	Pcln *pcln;

 	USED(sym);

 	if(p->as == ctxt->arch->ATEXT || p->as == ctxt->arch->ANOP || p->as == ctxt->arch->AUSEFIELD || p->lineno == 0 || phase == 1)
 		return oldval;
 	linkgetline(ctxt, p->lineno, &f, &l);
 	if(f == nil) {
 	//	print("getline failed for %s %P\n", ctxt->cursym->name, p);
 		return oldval;
 	}
 	if(arg == nil)
 		return l;
 	pcln = arg;

 	if(f == pcln->lastfile)
 		return pcln->lastindex;

 	for(i=0; i<pcln->nfile; i++) {
 		if(pcln->file[i] == f) {
 			pcln->lastfile = f;
 			pcln->lastindex = i;
 			return i;
 		}
 	}

 	if(pcln->nfile >= pcln->mfile) {
 		pcln->mfile = (pcln->nfile+1)*2;
 		pcln->file = erealloc(pcln->file, pcln->mfile*sizeof pcln->file[0]);
 	}
 	pcln->file[pcln->nfile++] = f;
 	pcln->lastfile = f;
 	pcln->lastindex = i;
 	return i;
 }

 // pctospadj computes the sp adjustment in effect.
 // It is oldval plus any adjustment made by p itself.
 // The adjustment by p takes effect only after p, so we
 // apply the change during phase == 1.
 static int32
 pctospadj(Link *ctxt, LSym *sym, int32 oldval, Prog *p, int32 phase, void *arg)
 {
 	USED(arg);
 	USED(sym);

 	if(oldval == -1) // starting
 		oldval = 0;
 	if(phase == 0)
 		return oldval;
 	if(oldval + p->spadj < -10000 || oldval + p->spadj > 1100000000) {
 		ctxt->diag("overflow in spadj: %d + %d = %d", oldval, p->spadj, oldval + p->spadj);
 		sysfatal("bad code");
 	}
 	return oldval + p->spadj;
 }

 // pctopcdata computes the pcdata value in effect at p.
 // A PCDATA instruction sets the value in effect at future
 // non-PCDATA instructions.
 // Since PCDATA instructions have no width in the final code,
 // it does not matter which phase we use for the update.
 static int32
 pctopcdata(Link *ctxt, LSym *sym, int32 oldval, Prog *p, int32 phase, void *arg)
 {
 	USED(sym);

 	if(phase == 0 || p->as != ctxt->arch->APCDATA || p->from.offset != (uintptr)arg)
 		return oldval;
 	if((int32)p->to.offset != p->to.offset) {
 		ctxt->diag("overflow in PCDATA instruction: %P", p);
 		sysfatal("bad code");
 	}
 	return p->to.offset;
 }

 void
 linkpcln(Link *ctxt, LSym *cursym)
 {
 	Prog *p;
 	Pcln *pcln;
 	int i, npcdata, nfuncdata, n;
 	uint32 *havepc, *havefunc;

 	ctxt->cursym = cursym;

 	pcln = emallocz(sizeof *pcln);
 	cursym->pcln = pcln;

 	npcdata = 0;
 	nfuncdata = 0;
 	for(p = cursym->text; p != nil; p = p->link) {
 		if(p->as == ctxt->arch->APCDATA && p->from.offset >= npcdata)
 			npcdata = p->from.offset+1;
 		if(p->as == ctxt->arch->AFUNCDATA && p->from.offset >= nfuncdata)
 			nfuncdata = p->from.offset+1;
 	}

 	pcln->pcdata = emallocz(npcdata*sizeof pcln->pcdata[0]);
 	pcln->npcdata = npcdata;
 	pcln->funcdata = emallocz(nfuncdata*sizeof pcln->funcdata[0]);
 	pcln->funcdataoff = emallocz(nfuncdata*sizeof pcln->funcdataoff[0]);
 	pcln->nfuncdata = nfuncdata;

 	funcpctab(ctxt, &pcln->pcsp, cursym, "pctospadj", pctospadj, nil);
 	funcpctab(ctxt, &pcln->pcfile, cursym, "pctofile", pctofileline, pcln);
 	funcpctab(ctxt, &pcln->pcline, cursym, "pctoline", pctofileline, nil);

 	// tabulate which pc and func data we have.
 	n = ((npcdata+31)/32 + (nfuncdata+31)/32)*4;
 	havepc = emallocz(n);
 	havefunc = havepc + (npcdata+31)/32;
 	for(p = cursym->text; p != nil; p = p->link) {
 		if(p->as == ctxt->arch->AFUNCDATA) {
 			if((havefunc[p->from.offset/32]>>(p->from.offset%32))&1)
 				ctxt->diag("multiple definitions for FUNCDATA $%d", p->from.offset);
 			havefunc[p->from.offset/32] |= 1<<(p->from.offset%32);
 		}
 		if(p->as == ctxt->arch->APCDATA)
 			havepc[p->from.offset/32] |= 1<<(p->from.offset%32);
 	}
 	// pcdata.
 	for(i=0; i<npcdata; i++) {
 		if(((havepc[i/32]>>(i%32))&1) == 0)
 			continue;
 		funcpctab(ctxt, &pcln->pcdata[i], cursym, "pctopcdata", pctopcdata, (void*)(uintptr)i);
 	}
 	free(havepc);

 	// funcdata
 	if(nfuncdata > 0) {
 		for(p = cursym->text; p != nil; p = p->link) {
 			if(p->as == ctxt->arch->AFUNCDATA) {
 				i = p->from.offset;
 				pcln->funcdataoff[i] = p->to.offset;
 				if(p->to.type != ctxt->arch->D_CONST) {
 					// TODO: Dedup.
 					//funcdata_bytes += p->to.sym->size;
 					pcln->funcdata[i] = p->to.sym;
 				}
 			}
 		}
 	}
 }

 // iteration over encoded pcdata tables.

 static uint32
 getvarint(uchar **pp)
 {
 	uchar *p;
 	int shift;
 	uint32 v;

 	v = 0;
 	p = *pp;
 	for(shift = 0;; shift += 7) {
 		v |= (uint32)(*p & 0x7F) << shift;
 		if(!(*p++ & 0x80))
 			break;
 	}
 	*pp = p;
 	return v;
 }

 void
 pciternext(Pciter *it)
 {
 	uint32 v;
 	int32 dv;

 	it->pc = it->nextpc;
 	if(it->done)
 		return;
 	if(it->p >= it->d.p + it->d.n) {
 		it->done = 1;
 		return;
 	}

 	// value delta
 	v = getvarint(&it->p);
 	if(v == 0 && !it->start) {
 		it->done = 1;
 		return;
 	}
 	it->start = 0;
 	dv = (int32)(v>>1) ^ ((int32)(v<<31)>>31);
 	it->value += dv;

 	// pc delta
 	v = getvarint(&it->p);
 	it->nextpc = it->pc + v*it->pcscale;
 }

 void
 pciterinit(Link *ctxt, Pciter *it, Pcdata *d)
 {
 	it->d = *d;
 	it->p = it->d.p;
 	it->pc = 0;
 	it->nextpc = 0;
 	it->value = -1;
 	it->start = 1;
 	it->done = 0;
 	it->pcscale = ctxt->arch->minlc;
 	pciternext(it);
 }
	// Copyright 2013 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>

	static void
	addvarint(Link ctxt, Pcdata d, uint32 val)
	{
	int32 n;
	uint32 v;
	uchar *p;

	USED(ctxt);

	n = 0;
	for(v = val; v >= 0x80; v >>= 7)
	n++;
	n++;

	if(d->n + n > d->m) {
	d->m = (d->n + n)*2;
	d->p = erealloc(d->p, d->m);
	}

	p = d->p + d->n;
	for(v = val; v >= 0x80; v >>= 7)
	*p++ = v \| 0x80;
	*p = v;
	d->n += n;
	}

	// funcpctab writes to dst a pc-value table mapping the code in func to the values
	// returned by valfunc parameterized by arg. The invocation of valfunc to update the
	// current value is, for each p,
	//
	// val = valfunc(func, val, p, 0, arg);
	// record val as value at p->pc;
	// val = valfunc(func, val, p, 1, arg);
	//
	// where func is the function, val is the current value, p is the instruction being
	// considered, and arg can be used to further parameterize valfunc.
	static void
	funcpctab(Link ctxt, Pcdata dst, LSym func, char desc, int32 (valfunc)(Link, LSym, int32, Prog, int32, void), void arg)
	{
	int dbg, i;
	int32 oldval, val, started;
	uint32 delta;
	vlong pc;
	Prog *p;

	// To debug a specific function, uncomment second line and change name.
	dbg = 0;
	//dbg = strcmp(func->name, "main.main") == 0;
	//dbg = strcmp(desc, "pctofile") == 0;

	ctxt->debugpcln += dbg;

	dst->n = 0;

	if(ctxt->debugpcln)
	Bprint(ctxt->bso, "funcpctab %s [valfunc=%s]\n", func->name, desc);

	val = -1;
	oldval = val;
	if(func->text == nil) {
	ctxt->debugpcln -= dbg;
	return;
	}

	pc = func->text->pc;

	if(ctxt->debugpcln)
	Bprint(ctxt->bso, "%6llux %6d %P\n", pc, val, func->text);

	started = 0;
	for(p=func->text; p != nil; p = p->link) {
	// Update val. If it's not changing, keep going.
	val = valfunc(ctxt, func, val, p, 0, arg);
	if(val == oldval && started) {
	val = valfunc(ctxt, func, val, p, 1, arg);
	if(ctxt->debugpcln)
	Bprint(ctxt->bso, "%6llux %6s %P\n", (vlong)p->pc, "", p);
	continue;
	}

	// If the pc of the next instruction is the same as the
	// pc of this instruction, this instruction is not a real
	// instruction. Keep going, so that we only emit a delta
	// for a true instruction boundary in the program.
	if(p->link && p->link->pc == p->pc) {
	val = valfunc(ctxt, func, val, p, 1, arg);
	if(ctxt->debugpcln)
	Bprint(ctxt->bso, "%6llux %6s %P\n", (vlong)p->pc, "", p);
	continue;
	}

	// The table is a sequence of (value, pc) pairs, where each
	// pair states that the given value is in effect from the current position
	// up to the given pc, which becomes the new current position.
	// To generate the table as we scan over the program instructions,
	// we emit a "(value" when pc == func->value, and then
	// each time we observe a change in value we emit ", pc) (value".
	// When the scan is over, we emit the closing ", pc)".
	//
	// The table is delta-encoded. The value deltas are signed and
	// transmitted in zig-zag form, where a complement bit is placed in bit 0,
	// and the pc deltas are unsigned. Both kinds of deltas are sent
	// as variable-length little-endian base-128 integers,
	// where the 0x80 bit indicates that the integer continues.

	if(ctxt->debugpcln)
	Bprint(ctxt->bso, "%6llux %6d %P\n", (vlong)p->pc, val, p);

	if(started) {
	addvarint(ctxt, dst, (p->pc - pc) / ctxt->arch->minlc);
	pc = p->pc;
	}
	delta = val - oldval;
	if(delta>>31)
	delta = 1 \| ~(delta<<1);
	else
	delta <<= 1;
	addvarint(ctxt, dst, delta);
	oldval = val;
	started = 1;
	val = valfunc(ctxt, func, val, p, 1, arg);
	}

	if(started) {
	if(ctxt->debugpcln)
	Bprint(ctxt->bso, "%6llux done\n", (vlong)func->text->pc+func->size);
	addvarint(ctxt, dst, (func->value+func->size - pc) / ctxt->arch->minlc);
	addvarint(ctxt, dst, 0); // terminator
	}

	if(ctxt->debugpcln) {
	Bprint(ctxt->bso, "wrote %d bytes to %p\n", dst->n, dst);
	for(i=0; i<dst->n; i++)
	Bprint(ctxt->bso, " %02ux", dst->p[i]);
	Bprint(ctxt->bso, "\n");
	}

	ctxt->debugpcln -= dbg;
	}

	// pctofileline computes either the file number (arg == 0)
	// or the line number (arg == 1) to use at p.
	// Because p->lineno applies to p, phase == 0 (before p)
	// takes care of the update.
	static int32
	pctofileline(Link ctxt, LSym sym, int32 oldval, Prog p, int32 phase, void arg)
	{
	int32 i, l;
	LSym *f;
	Pcln *pcln;

	USED(sym);

	if(p->as == ctxt->arch->ATEXT \|\| p->as == ctxt->arch->ANOP \|\| p->as == ctxt->arch->AUSEFIELD \|\| p->lineno == 0 \|\| phase == 1)
	return oldval;
	linkgetline(ctxt, p->lineno, &f, &l);
	if(f == nil) {
	// print("getline failed for %s %P\n", ctxt->cursym->name, p);
	return oldval;
	}
	if(arg == nil)
	return l;
	pcln = arg;

	if(f == pcln->lastfile)
	return pcln->lastindex;

	for(i=0; i<pcln->nfile; i++) {
	if(pcln->file[i] == f) {
	pcln->lastfile = f;
	pcln->lastindex = i;
	return i;
	}
	}

	if(pcln->nfile >= pcln->mfile) {
	pcln->mfile = (pcln->nfile+1)*2;
	pcln->file = erealloc(pcln->file, pcln->mfile*sizeof pcln->file[0]);
	}
	pcln->file[pcln->nfile++] = f;
	pcln->lastfile = f;
	pcln->lastindex = i;
	return i;
	}

	// pctospadj computes the sp adjustment in effect.
	// It is oldval plus any adjustment made by p itself.
	// The adjustment by p takes effect only after p, so we
	// apply the change during phase == 1.
	static int32
	pctospadj(Link ctxt, LSym sym, int32 oldval, Prog p, int32 phase, void arg)
	{
	USED(arg);
	USED(sym);

	if(oldval == -1) // starting
	oldval = 0;
	if(phase == 0)
	return oldval;
	if(oldval + p->spadj < -10000 \|\| oldval + p->spadj > 1100000000) {
	ctxt->diag("overflow in spadj: %d + %d = %d", oldval, p->spadj, oldval + p->spadj);
	sysfatal("bad code");
	}
	return oldval + p->spadj;
	}

	// pctopcdata computes the pcdata value in effect at p.
	// A PCDATA instruction sets the value in effect at future
	// non-PCDATA instructions.
	// Since PCDATA instructions have no width in the final code,
	// it does not matter which phase we use for the update.
	static int32
	pctopcdata(Link ctxt, LSym sym, int32 oldval, Prog p, int32 phase, void arg)
	{
	USED(sym);

	if(phase == 0 \|\| p->as != ctxt->arch->APCDATA \|\| p->from.offset != (uintptr)arg)
	return oldval;
	if((int32)p->to.offset != p->to.offset) {
	ctxt->diag("overflow in PCDATA instruction: %P", p);
	sysfatal("bad code");
	}
	return p->to.offset;
	}

	void
	linkpcln(Link ctxt, LSym cursym)
	{
	Prog *p;
	Pcln *pcln;
	int i, npcdata, nfuncdata, n;
	uint32 havepc, havefunc;

	ctxt->cursym = cursym;

	pcln = emallocz(sizeof *pcln);
	cursym->pcln = pcln;

	npcdata = 0;
	nfuncdata = 0;
	for(p = cursym->text; p != nil; p = p->link) {
	if(p->as == ctxt->arch->APCDATA && p->from.offset >= npcdata)
	npcdata = p->from.offset+1;
	if(p->as == ctxt->arch->AFUNCDATA && p->from.offset >= nfuncdata)
	nfuncdata = p->from.offset+1;
	}

	pcln->pcdata = emallocz(npcdata*sizeof pcln->pcdata[0]);
	pcln->npcdata = npcdata;
	pcln->funcdata = emallocz(nfuncdata*sizeof pcln->funcdata[0]);
	pcln->funcdataoff = emallocz(nfuncdata*sizeof pcln->funcdataoff[0]);
	pcln->nfuncdata = nfuncdata;

	funcpctab(ctxt, &pcln->pcsp, cursym, "pctospadj", pctospadj, nil);
	funcpctab(ctxt, &pcln->pcfile, cursym, "pctofile", pctofileline, pcln);
	funcpctab(ctxt, &pcln->pcline, cursym, "pctoline", pctofileline, nil);

	// tabulate which pc and func data we have.
	n = ((npcdata+31)/32 + (nfuncdata+31)/32)*4;
	havepc = emallocz(n);
	havefunc = havepc + (npcdata+31)/32;
	for(p = cursym->text; p != nil; p = p->link) {
	if(p->as == ctxt->arch->AFUNCDATA) {
	if((havefunc[p->from.offset/32]>>(p->from.offset%32))&1)
	ctxt->diag("multiple definitions for FUNCDATA $%d", p->from.offset);
	havefunc[p->from.offset/32] \|= 1<<(p->from.offset%32);
	}
	if(p->as == ctxt->arch->APCDATA)
	havepc[p->from.offset/32] \|= 1<<(p->from.offset%32);
	}
	// pcdata.
	for(i=0; i<npcdata; i++) {
	if(((havepc[i/32]>>(i%32))&1) == 0)
	continue;
	funcpctab(ctxt, &pcln->pcdata[i], cursym, "pctopcdata", pctopcdata, (void*)(uintptr)i);
	}
	free(havepc);

	// funcdata
	if(nfuncdata > 0) {
	for(p = cursym->text; p != nil; p = p->link) {
	if(p->as == ctxt->arch->AFUNCDATA) {
	i = p->from.offset;
	pcln->funcdataoff[i] = p->to.offset;
	if(p->to.type != ctxt->arch->D_CONST) {
	// TODO: Dedup.
	//funcdata_bytes += p->to.sym->size;
	pcln->funcdata[i] = p->to.sym;
	}
	}
	}
	}
	}

	// iteration over encoded pcdata tables.

	static uint32
	getvarint(uchar **pp)
	{
	uchar *p;
	int shift;
	uint32 v;

	v = 0;
	p = *pp;
	for(shift = 0;; shift += 7) {
	v \|= (uint32)(*p & 0x7F) << shift;
	if(!(*p++ & 0x80))
	break;
	}
	*pp = p;
	return v;
	}

	void
	pciternext(Pciter *it)
	{
	uint32 v;
	int32 dv;

	it->pc = it->nextpc;
	if(it->done)
	return;
	if(it->p >= it->d.p + it->d.n) {
	it->done = 1;
	return;
	}

	// value delta
	v = getvarint(&it->p);
	if(v == 0 && !it->start) {
	it->done = 1;
	return;
	}
	it->start = 0;
	dv = (int32)(v>>1) ^ ((int32)(v<<31)>>31);
	it->value += dv;

	// pc delta
	v = getvarint(&it->p);
	it->nextpc = it->pc + v*it->pcscale;
	}

	void
	pciterinit(Link ctxt, Pciter it, Pcdata *d)
	{
	it->d = *d;
	it->p = it->d.p;
	it->pc = 0;
	it->nextpc = 0;
	it->value = -1;
	it->start = 1;
	it->done = 0;
	it->pcscale = ctxt->arch->minlc;
	pciternext(it);
	}