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Optimize BUFHDR code generation.

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Rematerialize const buffer pointer instead of spilling.
This commit is contained in:
Mike Pall 2013-04-27 00:17:59 +02:00
parent 068783bf23
commit 723574d08c
1 changed files with 13 additions and 1 deletions
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14
src/lj_asm.c
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@ -1040,7 +1040,19 @@ static void asm_tvptr(ASMState *as, Reg dest, IRRef ref);
static void asm_bufhdr(ASMState *as, IRIns *ir)
{
Reg sb = ra_dest(as, ir, RSET_GPR);
if (!(ir->op2 & IRBUFHDR_APPEND)) {
if ((ir->op2 & IRBUFHDR_APPEND)) {
/* Rematerialize const buffer pointer instead of likely spill. */
IRIns *irp = IR(ir->op1);
if (!(ra_hasreg(irp->r) || irp == ir-1 ||
(irp == ir-2 && !ra_used(ir-1)))) {
while (!(irp->o == IR_BUFHDR && !(irp->op2 & IRBUFHDR_APPEND)))
irp = IR(irp->op1);
if (irref_isk(irp->op1)) {
ra_weak(as, ra_allocref(as, ir->op1, RSET_GPR));
ir = irp;
}
}
} else {
Reg tmp = ra_scratch(as, rset_exclude(RSET_GPR, sb));
/* Passing ir isn't strictly correct, but it's an IRT_P32, too. */
emit_storeofs(as, ir, tmp, sb, offsetof(SBuf, p));