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Commit 1a6576db authored by Russ Cox's avatar Russ Cox
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cmd/5l, cmd/6l, cmd/8l: refactor stack split code 

Pull the stack split generation into its own function.
This will make an upcoming change to fix recover
easier to digest.

R=ken2
CC=golang-dev
https://golang.org/cl/13611044
parent bab302de
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Showing with 144 additions and 133 deletions
src/cmd/5l/noop.c
View file @ 1a6576db
......@@ -38,6 +38,10 @@ static Sym* sym_div;
static Sym* sym_divu;
static Sym* sym_mod;
static Sym* sym_modu;
static Sym* symmorestack;
static Prog* pmorestack;
static Prog* stacksplit(Prog*, int32);
static void
linkcase(Prog *casep)
......@@ -58,9 +62,7 @@ noops(void)
{
Prog *p, *q, *q1, *q2;
int o;
int32 arg;
Prog *pmorestack;
Sym *symmorestack, *tlsfallback, *gmsym;
Sym *tlsfallback, *gmsym;
/*
* find leaf subroutines
......@@ -256,136 +258,8 @@ noops(void)
break;
}
if(!(p->reg & NOSPLIT)) {
// MOVW g_stackguard(g), R1
p = appendp(p);
p->as = AMOVW;
p->from.type = D_OREG;
p->from.reg = REGG;
p->to.type = D_REG;
p->to.reg = 1;
if(autosize <= StackSmall) {
// small stack: SP < stackguard
// CMP stackguard, SP
p = appendp(p);
p->as = ACMP;
p->from.type = D_REG;
p->from.reg = 1;
p->reg = REGSP;
} else if(autosize <= StackBig) {
// large stack: SP-framesize < stackguard-StackSmall
// MOVW $-autosize(SP), R2
// CMP stackguard, R2
p = appendp(p);
p->as = AMOVW;
p->from.type = D_CONST;
p->from.reg = REGSP;
p->from.offset = -autosize;
p->to.type = D_REG;
p->to.reg = 2;
p = appendp(p);
p->as = ACMP;
p->from.type = D_REG;
p->from.reg = 1;
p->reg = 2;
} 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.
// CMP $StackPreempt, R1
// MOVW.NE $StackGuard(SP), R2
// SUB.NE R1, R2
// MOVW.NE $(autosize+(StackGuard-StackSmall)), R3
// CMP.NE R3, R2
p = appendp(p);
p->as = ACMP;
p->from.type = D_CONST;
p->from.offset = (uint32)StackPreempt;
p->reg = 1;
p = appendp(p);
p->as = AMOVW;
p->from.type = D_CONST;
p->from.reg = REGSP;
p->from.offset = StackGuard;
p->to.type = D_REG;
p->to.reg = 2;
p->scond = C_SCOND_NE;
p = appendp(p);
p->as = ASUB;
p->from.type = D_REG;
p->from.reg = 1;
p->to.type = D_REG;
p->to.reg = 2;
p->scond = C_SCOND_NE;
p = appendp(p);
p->as = AMOVW;
p->from.type = D_CONST;
p->from.offset = autosize + (StackGuard - StackSmall);
p->to.type = D_REG;
p->to.reg = 3;
p->scond = C_SCOND_NE;
p = appendp(p);
p->as = ACMP;
p->from.type = D_REG;
p->from.reg = 3;
p->reg = 2;
p->scond = C_SCOND_NE;
}
// MOVW.LS $autosize, R1
p = appendp(p);
p->as = AMOVW;
p->scond = C_SCOND_LS;
p->from.type = D_CONST;
p->from.offset = autosize;
p->to.type = D_REG;
p->to.reg = 1;
// MOVW.LS $args, R2
p = appendp(p);
p->as = AMOVW;
p->scond = C_SCOND_LS;
p->from.type = D_CONST;
arg = cursym->text->to.offset2;
if(arg == 1) // special marker for known 0
arg = 0;
if(arg&3)
diag("misaligned argument size in stack split");
p->from.offset = arg;
p->to.type = D_REG;
p->to.reg = 2;
// MOVW.LS R14, R3
p = appendp(p);
p->as = AMOVW;
p->scond = C_SCOND_LS;
p->from.type = D_REG;
p->from.reg = REGLINK;
p->to.type = D_REG;
p->to.reg = 3;
// BL.LS runtime.morestack(SB) // modifies LR, returns with LO still asserted
p = appendp(p);
p->as = ABL;
p->scond = C_SCOND_LS;
p->to.type = D_BRANCH;
p->to.sym = symmorestack;
p->cond = pmorestack;
// BLS start
p = appendp(p);
p->as = ABLS;
p->to.type = D_BRANCH;
p->cond = cursym->text->link;
}
if(!(p->reg & NOSPLIT))
p = stacksplit(p, autosize); // emit split check
// MOVW.W R14,$-autosize(SP)
p = appendp(p);
......@@ -554,6 +428,143 @@ noops(void)
}
}
static Prog*
stacksplit(Prog *p, int32 framesize)
{
int32 arg;
// MOVW g_stackguard(g), R1
p = appendp(p);
p->as = AMOVW;
p->from.type = D_OREG;
p->from.reg = REGG;
p->to.type = D_REG;
p->to.reg = 1;
if(framesize <= StackSmall) {
// small stack: SP < stackguard
// CMP stackguard, SP
p = appendp(p);
p->as = ACMP;
p->from.type = D_REG;
p->from.reg = 1;
p->reg = REGSP;
} else if(framesize <= StackBig) {
// large stack: SP-framesize < stackguard-StackSmall
// MOVW $-framesize(SP), R2
// CMP stackguard, R2
p = appendp(p);
p->as = AMOVW;
p->from.type = D_CONST;
p->from.reg = REGSP;
p->from.offset = -framesize;
p->to.type = D_REG;
p->to.reg = 2;
p = appendp(p);
p->as = ACMP;
p->from.type = D_REG;
p->from.reg = 1;
p->reg = 2;
} 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.
// CMP $StackPreempt, R1
// MOVW.NE $StackGuard(SP), R2
// SUB.NE R1, R2
// MOVW.NE $(framesize+(StackGuard-StackSmall)), R3
// CMP.NE R3, R2
p = appendp(p);
p->as = ACMP;
p->from.type = D_CONST;
p->from.offset = (uint32)StackPreempt;
p->reg = 1;
p = appendp(p);
p->as = AMOVW;
p->from.type = D_CONST;
p->from.reg = REGSP;
p->from.offset = StackGuard;
p->to.type = D_REG;
p->to.reg = 2;
p->scond = C_SCOND_NE;
p = appendp(p);
p->as = ASUB;
p->from.type = D_REG;
p->from.reg = 1;
p->to.type = D_REG;
p->to.reg = 2;
p->scond = C_SCOND_NE;
p = appendp(p);
p->as = AMOVW;
p->from.type = D_CONST;
p->from.offset = framesize + (StackGuard - StackSmall);
p->to.type = D_REG;
p->to.reg = 3;
p->scond = C_SCOND_NE;
p = appendp(p);
p->as = ACMP;
p->from.type = D_REG;
p->from.reg = 3;
p->reg = 2;
p->scond = C_SCOND_NE;
}
// MOVW.LS $framesize, R1
p = appendp(p);
p->as = AMOVW;
p->scond = C_SCOND_LS;
p->from.type = D_CONST;
p->from.offset = framesize;
p->to.type = D_REG;
p->to.reg = 1;
// MOVW.LS $args, R2
p = appendp(p);
p->as = AMOVW;
p->scond = C_SCOND_LS;
p->from.type = D_CONST;
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->from.offset = arg;
p->to.type = D_REG;
p->to.reg = 2;
// MOVW.LS R14, R3
p = appendp(p);
p->as = AMOVW;
p->scond = C_SCOND_LS;
p->from.type = D_REG;
p->from.reg = REGLINK;
p->to.type = D_REG;
p->to.reg = 3;
// BL.LS runtime.morestack(SB) // modifies LR, returns with LO still asserted
p = appendp(p);
p->as = ABL;
p->scond = C_SCOND_LS;
p->to.type = D_BRANCH;
p->to.sym = symmorestack;
p->cond = pmorestack;
// BLS start
p = appendp(p);
p->as = ABLS;
p->to.type = D_BRANCH;
p->cond = cursym->text->link;
return p;
}
static void
sigdiv(char *n)
{
......
src/cmd/6l/pass.c
View file @ 1a6576db
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src/cmd/8l/pass.c
View file @ 1a6576db
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