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// Inferno utils/8l/pass.c
// http://code.google.com/p/inferno-os/source/browse/utils/8l/pass.c
//
// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
// Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
// Portions Copyright © 1997-1999 Vita Nuova Limited
// Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
// Portions Copyright © 2004,2006 Bruce Ellis
// Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
// Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
// Portions Copyright © 2009 The Go Authors. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
// Code and data passes.
#include "l.h"
#include "../ld/lib.h"
#include "../../pkg/runtime/stack.h"
static void xfol(Prog*, Prog**);
Prog*
brchain(Prog *p)
{
int i;
for(i=0; i<20; i++) {
if(p == P || p->as != AJMP)
return p;
p = p->pcond;
}
return P;
}
void
follow(void)
{
Prog *firstp, *lastp;
if(debug['v'])
Bprint(&bso, "%5.2f follow\n", cputime());
Bflush(&bso);
for(cursym = textp; cursym != nil; cursym = cursym->next) {
firstp = prg();
lastp = firstp;
xfol(cursym->text, &lastp);
lastp->link = nil;
cursym->text = firstp->link;
}
}
static int
nofollow(int a)
{
switch(a) {
case AJMP:
case ARET:
case AIRETL:
case AIRETW:
case AUNDEF:
return 1;
}
return 0;
}
static int
pushpop(int a)
{
switch(a) {
case APUSHL:
case APUSHFL:
case APUSHW:
case APUSHFW:
case APOPL:
case APOPFL:
case APOPW:
case APOPFW:
return 1;
}
return 0;
}
static void
xfol(Prog *p, Prog **last)
{
Prog *q;
int i;
enum as a;
loop:
if(p == P)
return;
if(p->as == AJMP)
if((q = p->pcond) != P && q->as != ATEXT) {
/* mark instruction as done and continue layout at target of jump */
p->mark = 1;
p = q;
if(p->mark == 0)
goto loop;
}
if(p->mark) {
/*
* p goes here, but already used it elsewhere.
* copy up to 4 instructions or else branch to other copy.
*/
for(i=0,q=p; i<4; i++,q=q->link) {
if(q == P)
break;
if(q == *last)
break;
a = q->as;
if(a == ANOP) {
i--;
continue;
}
if(nofollow(a) || pushpop(a))
break; // NOTE(rsc): arm does goto copy
if(q->pcond == P || q->pcond->mark)
continue;
if(a == ACALL || a == ALOOP)
continue;
for(;;) {
if(p->as == ANOP) {
p = p->link;
continue;
}
q = copyp(p);
p = p->link;
q->mark = 1;
(*last)->link = q;
*last = q;
if(q->as != a || q->pcond == P || q->pcond->mark)
continue;
q->as = relinv(q->as);
p = q->pcond;
q->pcond = q->link;
q->link = p;
xfol(q->link, last);
p = q->link;
if(p->mark)
return;
goto loop;
}
} /* */
q = prg();
q->as = AJMP;
q->line = p->line;
q->to.type = D_BRANCH;
q->to.offset = p->pc;
q->pcond = p;
p = q;
}
/* emit p */
p->mark = 1;
(*last)->link = p;
*last = p;
a = p->as;
/* continue loop with what comes after p */
if(nofollow(a))
return;
if(p->pcond != P && a != ACALL) {
/*
* some kind of conditional branch.
* recurse to follow one path.
* continue loop on the other.
*/
if((q = brchain(p->pcond)) != P)
p->pcond = q;
if((q = brchain(p->link)) != P)
p->link = q;
if(p->from.type == D_CONST) {
if(p->from.offset == 1) {
/*
* expect conditional jump to be taken.
* rewrite so that's the fall-through case.
*/
p->as = relinv(a);
q = p->link;
p->link = p->pcond;
p->pcond = q;
}
} else {
q = p->link;
if(q->mark)
if(a != ALOOP) {
p->as = relinv(a);
p->link = p->pcond;
p->pcond = q;
}
}
xfol(p->link, last);
if(p->pcond->mark)
return;
p = p->pcond;
goto loop;
}
p = p->link;
goto loop;
}
int
relinv(int a)
{
switch(a) {
case AJEQ: return AJNE;
case AJNE: return AJEQ;
case AJLE: return AJGT;
case AJLS: return AJHI;
case AJLT: return AJGE;
case AJMI: return AJPL;
case AJGE: return AJLT;
case AJPL: return AJMI;
case AJGT: return AJLE;
case AJHI: return AJLS;
case AJCS: return AJCC;
case AJCC: return AJCS;
case AJPS: return AJPC;
case AJPC: return AJPS;
case AJOS: return AJOC;
case AJOC: return AJOS;
}
diag("unknown relation: %s in %s", anames[a], TNAME);
return a;
}
void
patch(void)
{
int32 c;
Prog *p, *q;
Sym *s;
int32 vexit;
Sym *plan9_tos;
if(debug['v'])
Bprint(&bso, "%5.2f mkfwd\n", cputime());
Bflush(&bso);
mkfwd();
if(debug['v'])
Bprint(&bso, "%5.2f patch\n", cputime());
Bflush(&bso);
s = lookup("exit", 0);
vexit = s->value;
plan9_tos = S;
if(HEADTYPE == Hplan9x32)
plan9_tos = lookup("_tos", 0);
for(cursym = textp; cursym != nil; cursym = cursym->next) {
for(p = cursym->text; p != P; p = p->link) {
if(HEADTYPE == Hwindows) {
// Convert
// op n(GS), reg
// to
// MOVL 0x14(FS), reg
// op n(reg), reg
// The purpose of this patch is to fix some accesses
// to extern register variables (TLS) on Windows, as
// a different method is used to access them.
if(p->from.type == D_INDIR+D_GS
&& p->to.type >= D_AX && p->to.type <= D_DI) {
q = appendp(p);
q->from = p->from;
q->from.type = D_INDIR + p->to.type;
q->to = p->to;
q->as = p->as;
p->as = AMOVL;
p->from.type = D_INDIR+D_FS;
p->from.offset = 0x14;
}
}
if(HEADTYPE == Hlinux) {
// Running binaries under Xen requires using
// MOVL 0(GS), reg
// and then off(reg) instead of saying off(GS) directly
// when the offset is negative.
// In external mode we just produce a reloc.
if(p->from.type == D_INDIR+D_GS && p->from.offset < 0
&& p->to.type >= D_AX && p->to.type <= D_DI) {
if(linkmode != LinkExternal) {
q = appendp(p);
q->from = p->from;
q->from.type = D_INDIR + p->to.type;
q->to = p->to;
q->as = p->as;
p->as = AMOVL;
p->from.type = D_INDIR+D_GS;
p->from.offset = 0;
} else {
// Add signals to relocate.
p->from.index = D_GS;
p->from.scale = 1;
}
}
}
if(HEADTYPE == Hplan9x32) {
if(p->from.type == D_INDIR+D_GS
&& p->to.type >= D_AX && p->to.type <= D_DI) {
q = appendp(p);
q->from = p->from;
q->from.type = D_INDIR + p->to.type;
q->to = p->to;
q->as = p->as;
p->as = AMOVL;
p->from.type = D_EXTERN;
p->from.sym = plan9_tos;
p->from.offset = 0;
}
}
if((p->as == ACALL && p->to.type != D_BRANCH) || (p->as == AJMP && p->to.type != D_BRANCH) || (p->as == ARET && p->to.sym != nil)) {
s = p->to.sym;
if(p->to.type == D_INDIR+D_ADDR) {
/* skip check if this is an indirect call (CALL *symbol(SB)) */
continue;
} else if(s) {
if(debug['c'])
Bprint(&bso, "%s calls %s\n", TNAME, s->name);
if((s->type&SMASK) != STEXT) {
/* diag prints TNAME first */
diag("undefined: %s", s->name);
s->type = STEXT;
s->value = vexit;
continue; // avoid more error messages
}
if(s->text == nil)
continue;
p->to.type = D_BRANCH;
p->to.offset = s->text->pc;
p->pcond = s->text;
continue;
}
}
if(p->to.type != D_BRANCH)
continue;
c = p->to.offset;
for(q = cursym->text; q != P;) {
if(c == q->pc)
break;
if(q->forwd != P && c >= q->forwd->pc)
q = q->forwd;
else
q = q->link;
}
if(q == P) {
diag("branch out of range in %s (%#ux)\n%P [%s]",
TNAME, c, p, p->to.sym ? p->to.sym->name : "<nil>");
p->to.type = D_NONE;
}
p->pcond = q;
}
}
for(cursym = textp; cursym != nil; cursym = cursym->next) {
if(cursym->text == nil || cursym->p != nil)
continue;
for(p = cursym->text; p != P; p = p->link) {
p->mark = 0; /* initialization for follow */
if(p->pcond != P) {
p->pcond = brloop(p->pcond);
if(p->pcond != P)
if(p->to.type == D_BRANCH)
p->to.offset = p->pcond->pc;
}
}
}
}
Prog*
brloop(Prog *p)
{
int c;
Prog *q;
c = 0;
for(q = p; q != P; q = q->pcond) {
if(q->as != AJMP)
break;
c++;
if(c >= 5000)
return P;
}
return q;
}
static Prog* load_g_cx(Prog*);
static Prog* stacksplit(Prog*, int32, Prog**);
static Sym *plan9_tos;
static Prog *pmorestack;
static Sym *symmorestack;
void
dostkoff(void)
{
Prog *p, *q;
int32 autoffset, deltasp;
int a;
pmorestack = P;
symmorestack = lookup("runtime.morestack", 0);
if(symmorestack->type != STEXT)
diag("runtime.morestack not defined");
else {
pmorestack = symmorestack->text;
symmorestack->text->from.scale |= NOSPLIT;
}
plan9_tos = S;
if(HEADTYPE == Hplan9x32)
plan9_tos = lookup("_tos", 0);
for(cursym = textp; cursym != nil; cursym = cursym->next) {
if(cursym->text == nil || cursym->text->link == nil)
continue;
p = cursym->text;
autoffset = p->to.offset;
if(autoffset < 0)
autoffset = 0;
q = P;
if(!(p->from.scale & NOSPLIT) || (p->from.scale & WRAPPER)) {
p = appendp(p);
p = load_g_cx(p); // load g into CX
}
if(!(cursym->text->from.scale & NOSPLIT))
p = stacksplit(p, autoffset, &q); // emit split check
if(autoffset) {
p = appendp(p);
p->as = AADJSP;
p->from.type = D_CONST;
p->from.offset = autoffset;
p->spadj = autoffset;
} else {
// zero-byte stack adjustment.
// Insert a fake non-zero adjustment so that stkcheck can
// recognize the end of the stack-splitting prolog.
p = appendp(p);
p->as = ANOP;
p->spadj = -PtrSize;
p = appendp(p);
p->as = ANOP;
p->spadj = PtrSize;
}
if(q != P)
q->pcond = p;
deltasp = autoffset;
if(cursym->text->from.scale & WRAPPER) {
// g->panicwrap += autoffset + PtrSize;
p = appendp(p);
p->as = AADDL;
p->from.type = D_CONST;
p->from.offset = autoffset + PtrSize;
p->to.type = D_INDIR+D_CX;
p->to.offset = 2*PtrSize;
}
if(debug['Z'] && autoffset && !(cursym->text->from.scale&NOSPLIT)) {
// 8l -Z means zero the stack frame on entry.
// This slows down function calls but can help avoid
// false positives in garbage collection.
p = appendp(p);
p->as = AMOVL;
p->from.type = D_SP;
p->to.type = D_DI;
p = appendp(p);
p->as = AMOVL;
p->from.type = D_CONST;
p->from.offset = autoffset/4;
p->to.type = D_CX;
p = appendp(p);
p->as = AMOVL;
p->from.type = D_CONST;
p->from.offset = 0;
p->to.type = D_AX;
p = appendp(p);
p->as = AREP;
p = appendp(p);
p->as = ASTOSL;
}
for(; p != P; p = p->link) {
a = p->from.type;
if(a == D_AUTO)
p->from.offset += deltasp;
if(a == D_PARAM)
p->from.offset += deltasp + 4;
a = p->to.type;
if(a == D_AUTO)
p->to.offset += deltasp;
if(a == D_PARAM)
p->to.offset += deltasp + 4;
switch(p->as) {
default:
continue;
case APUSHL:
case APUSHFL:
deltasp += 4;
p->spadj = 4;
continue;
case APUSHW:
case APUSHFW:
deltasp += 2;
p->spadj = 2;
continue;
case APOPL:
case APOPFL:
deltasp -= 4;
p->spadj = -4;
continue;
case APOPW:
case APOPFW:
deltasp -= 2;
p->spadj = -2;
continue;
case ARET:
break;
}
if(autoffset != deltasp)
diag("unbalanced PUSH/POP");
if(cursym->text->from.scale & WRAPPER) {
p = load_g_cx(p);
p = appendp(p);
// g->panicwrap -= autoffset + PtrSize;
p->as = ASUBL;
p->from.type = D_CONST;
p->from.offset = autoffset + PtrSize;
p->to.type = D_INDIR+D_CX;
p->to.offset = 2*PtrSize;
p = appendp(p);
p->as = ARET;
}
if(autoffset) {
p->as = AADJSP;
p->from.type = D_CONST;
p->from.offset = -autoffset;
p->spadj = -autoffset;
p = appendp(p);
p->as = ARET;
// If there are instructions following
// this ARET, they come from a branch
// with the same stackframe, so undo
// the cleanup.
p->spadj = +autoffset;
}
if(p->to.sym) // retjmp
p->as = AJMP;
}
}
}
// Append code to p to load g into cx.
// Overwrites p with the first instruction (no first appendp).
// Overwriting p is unusual but it lets use this in both the
// prologue (caller must call appendp first) and in the epilogue.
// Returns last new instruction.
static Prog*
load_g_cx(Prog *p)
{
switch(HEADTYPE) {
case Hwindows:
p->as = AMOVL;
p->from.type = D_INDIR+D_FS;
p->from.offset = 0x14;
p->to.type = D_CX;
p = appendp(p);
p->as = AMOVL;
p->from.type = D_INDIR+D_CX;
p->from.offset = 0;
p->to.type = D_CX;
break;
case Hlinux:
if(linkmode != LinkExternal) {
p->as = AMOVL;
p->from.type = D_INDIR+D_GS;
p->from.offset = 0;
p->to.type = D_CX;
p = appendp(p);
p->as = AMOVL;
p->from.type = D_INDIR+D_CX;
p->from.offset = tlsoffset + 0;
p->to.type = D_CX;
} else {
p->as = AMOVL;
p->from.type = D_INDIR+D_GS;
p->from.offset = tlsoffset + 0;
p->to.type = D_CX;
p->from.index = D_GS;
p->from.scale = 1;
}
break;
case Hplan9x32:
p->as = AMOVL;
p->from.type = D_EXTERN;
p->from.sym = plan9_tos;
p->to.type = D_CX;
p = appendp(p);
p->as = AMOVL;
p->from.type = D_INDIR+D_CX;
p->from.offset = tlsoffset + 0;
p->to.type = D_CX;
break;
default:
p->as = AMOVL;
p->from.type = D_INDIR+D_GS;
p->from.offset = tlsoffset + 0;
p->to.type = D_CX;
}
return p;
}
// Append code to p to check for stack split.
// Appends to (does not overwrite) p.
// Assumes g is in CX.
// Returns last new instruction.
// On return, *jmpok is the instruction that should jump
// to the stack frame allocation if no split is needed.
static Prog*
stacksplit(Prog *p, int32 framesize, Prog **jmpok)
{
Prog *q, *q1;
int arg;
if(debug['K']) {
// 8l -K means check not only for stack
// overflow but stack underflow.
// On underflow, INT 3 (breakpoint).
// Underflow itself is rare but this also
// catches out-of-sync stack guard info.
p = appendp(p);
p->as = ACMPL;
p->from.type = D_INDIR+D_CX;
p->from.offset = 4;
p->to.type = D_SP;
p = appendp(p);
p->as = AJCC;
p->to.type = D_BRANCH;
p->to.offset = 4;
q1 = p;
p = appendp(p);
p->as = AINT;
p->from.type = D_CONST;
p->from.offset = 3;
p = appendp(p);
p->as = ANOP;
q1->pcond = p;
}
q1 = P;
if(framesize <= StackSmall) {
// small stack: SP <= stackguard
// CMPL SP, stackguard
p = appendp(p);
p->as = ACMPL;
p->from.type = D_SP;
p->to.type = D_INDIR+D_CX;
} else if(framesize <= StackBig) {
// large stack: SP-framesize <= stackguard-StackSmall
// LEAL -(framesize-StackSmall)(SP), AX
// CMPL AX, stackguard
p = appendp(p);
p->as = ALEAL;
p->from.type = D_INDIR+D_SP;
p->from.offset = -(framesize-StackSmall);
p->to.type = D_AX;
p = appendp(p);
p->as = ACMPL;
p->from.type = D_AX;
p->to.type = D_INDIR+D_CX;
} else {
// Such a large stack we need to protect against wraparound
// if SP is close to zero.
// SP-stackguard+StackGuard <= framesize + (StackGuard-StackSmall)
// The +StackGuard on both sides is required to keep the left side positive:
// SP is allowed to be slightly below stackguard. See stack.h.
//
// Preemption sets stackguard to StackPreempt, a very large value.
// That breaks the math above, so we have to check for that explicitly.
// MOVL stackguard, CX
// CMPL CX, $StackPreempt
// JEQ label-of-call-to-morestack
// LEAL StackGuard(SP), AX
// SUBL stackguard, AX
// CMPL AX, $(framesize+(StackGuard-StackSmall))
p = appendp(p);
p->as = AMOVL;
p->from.type = D_INDIR+D_CX;
p->from.offset = 0;
p->to.type = D_SI;
p = appendp(p);
p->as = ACMPL;
p->from.type = D_SI;
p->to.type = D_CONST;
p->to.offset = (uint32)StackPreempt;
p = appendp(p);
p->as = AJEQ;
p->to.type = D_BRANCH;
q1 = p;
p = appendp(p);
p->as = ALEAL;
p->from.type = D_INDIR+D_SP;
p->from.offset = StackGuard;
p->to.type = D_AX;
p = appendp(p);
p->as = ASUBL;
p->from.type = D_SI;
p->from.offset = 0;
p->to.type = D_AX;
p = appendp(p);
p->as = ACMPL;
p->from.type = D_AX;
p->to.type = D_CONST;
p->to.offset = framesize+(StackGuard-StackSmall);
}
// common
p = appendp(p);
p->as = AJHI;
p->to.type = D_BRANCH;
p->to.offset = 4;
q = p;
p = appendp(p); // save frame size in DI
p->as = AMOVL;
p->to.type = D_DI;
p->from.type = D_CONST;
// If we ask for more stack, we'll get a minimum of StackMin bytes.
// We need a stack frame large enough to hold the top-of-stack data,
// the function arguments+results, our caller's PC, our frame,
// a word for the return PC of the next call, and then the StackLimit bytes
// that must be available on entry to any function called from a function
// that did a stack check. If StackMin is enough, don't ask for a specific
// amount: then we can use the custom functions and save a few
// instructions.
if(StackTop + cursym->text->to.offset2 + PtrSize + framesize + PtrSize + StackLimit >= StackMin)
p->from.offset = (framesize+7) & ~7LL;
arg = cursym->text->to.offset2;
if(arg == 1) // special marker for known 0
arg = 0;
if(arg&3)
diag("misaligned argument size in stack split");
p = appendp(p); // save arg size in AX
p->as = AMOVL;
p->to.type = D_AX;
p->from.type = D_CONST;
p->from.offset = arg;
p = appendp(p);
p->as = ACALL;
p->to.type = D_BRANCH;
p->pcond = pmorestack;
p->to.sym = symmorestack;
p = appendp(p);
p->as = AJMP;
p->to.type = D_BRANCH;
p->pcond = cursym->text->link;
if(q != P)
q->pcond = p->link;
if(q1 != P)
q1->pcond = q->link;
*jmpok = q;
return p;
}
int32
atolwhex(char *s)
{
int32 n;
int f;
n = 0;
f = 0;
while(*s == ' ' || *s == '\t')
s++;
if(*s == '-' || *s == '+') {
if(*s++ == '-')
f = 1;
while(*s == ' ' || *s == '\t')
s++;
}
if(s[0]=='0' && s[1]){
if(s[1]=='x' || s[1]=='X'){
s += 2;
for(;;){
if(*s >= '0' && *s <= '9')
n = n*16 + *s++ - '0';
else if(*s >= 'a' && *s <= 'f')
n = n*16 + *s++ - 'a' + 10;
else if(*s >= 'A' && *s <= 'F')
n = n*16 + *s++ - 'A' + 10;
else
break;
}
} else
while(*s >= '0' && *s <= '7')
n = n*8 + *s++ - '0';
} else
while(*s >= '0' && *s <= '9')
n = n*10 + *s++ - '0';
if(f)
n = -n;
return n;
}