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Add guard for obscure aliasing between open upvalues and SSA slots.

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Thanks to Peter Cawley.
This commit is contained in:
Mike Pall 2016-05-20 20:24:06 +02:00
parent 5837c2a2fb
commit 37e1e70313
6 changed files with 8 additions and 12 deletions
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6
doc/status.html
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@ -89,12 +89,6 @@ hooks for non-Lua functions) and shows slightly different behavior
in LuaJIT (no per-coroutine hooks, no tail call counting).
</li>
<li>
Some checks are missing in the JIT-compiled code for obscure situations
with <b>open upvalues aliasing</b> one of the SSA slots later on (or
vice versa). Bonus points, if you can find a real world test case for
this.
</li>
<li>
Currently some <b>out-of-memory</b> errors from <b>on-trace code</b> are not
handled correctly. The error may fall through an on-trace
<tt>pcall</tt> or it may be passed on to the function set with

1
src/lj_asm_arm.h
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@ -976,7 +976,6 @@ static void asm_newref(ASMState *as, IRIns *ir)
static void asm_uref(ASMState *as, IRIns *ir)
{
/* NYI: Check that UREFO is still open and not aliasing a slot. */
Reg dest = ra_dest(as, ir, RSET_GPR);
if (irref_isk(ir->op1)) {
GCfunc *fn = ir_kfunc(IR(ir->op1));

1
src/lj_asm_mips.h
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@ -793,7 +793,6 @@ static void asm_newref(ASMState *as, IRIns *ir)
static void asm_uref(ASMState *as, IRIns *ir)
{
/* NYI: Check that UREFO is still open and not aliasing a slot. */
Reg dest = ra_dest(as, ir, RSET_GPR);
if (irref_isk(ir->op1)) {
GCfunc *fn = ir_kfunc(IR(ir->op1));

1
src/lj_asm_ppc.h
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@ -789,7 +789,6 @@ static void asm_newref(ASMState *as, IRIns *ir)
static void asm_uref(ASMState *as, IRIns *ir)
{
/* NYI: Check that UREFO is still open and not aliasing a slot. */
Reg dest = ra_dest(as, ir, RSET_GPR);
if (irref_isk(ir->op1)) {
GCfunc *fn = ir_kfunc(IR(ir->op1));

1
src/lj_asm_x86.h
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@ -1215,7 +1215,6 @@ static void asm_newref(ASMState *as, IRIns *ir)
static void asm_uref(ASMState *as, IRIns *ir)
{
/* NYI: Check that UREFO is still open and not aliasing a slot. */
Reg dest = ra_dest(as, ir, RSET_GPR);
if (irref_isk(ir->op1)) {
GCfunc *fn = ir_kfunc(IR(ir->op1));

10
src/lj_record.c
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@ -1343,13 +1343,17 @@ noconstify:
/* Note: this effectively limits LJ_MAX_UPVAL to 127. */
uv = (uv << 8) | (hashrot(uvp->dhash, uvp->dhash + HASH_BIAS) & 0xff);
if (!uvp->closed) {
uref = tref_ref(emitir(IRTG(IR_UREFO, IRT_P32), fn, uv));
/* In current stack? */
if (uvval(uvp) >= tvref(J->L->stack) &&
uvval(uvp) < tvref(J->L->maxstack)) {
int32_t slot = (int32_t)(uvval(uvp) - (J->L->base - J->baseslot));
if (slot >= 0) { /* Aliases an SSA slot? */
emitir(IRTG(IR_EQ, IRT_P32),
REF_BASE,
emitir(IRT(IR_ADD, IRT_P32), uref,
lj_ir_kint(J, (slot - 1) * -8)));
slot -= (int32_t)J->baseslot; /* Note: slot number may be negative! */
/* NYI: add IR to guard that it's still aliasing the same slot. */
if (val == 0) {
return getslot(J, slot);
} else {
@ -1359,7 +1363,9 @@ noconstify:
}
}
}
uref = tref_ref(emitir(IRTG(IR_UREFO, IRT_P32), fn, uv));
emitir(IRTG(IR_UGT, IRT_P32),
emitir(IRT(IR_SUB, IRT_P32), uref, REF_BASE),
lj_ir_kint(J, (J->baseslot + J->maxslot) * 8));
} else {
needbarrier = 1;
uref = tref_ref(emitir(IRTG(IR_UREFC, IRT_P32), fn, uv));