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Don't generate phis if unnecessary (because this breaks the

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critical-edge-splitting guarantee and causes insertion of phi copies to fail).
This commit is contained in:
David Given 2016-10-29 10:55:48 +02:00
parent 658db4ba71
commit bfa65168e2
1 changed files with 23 additions and 7 deletions
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30
mach/proto/mcg/pass_convertstackops.c
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@ -95,15 +95,31 @@ static void convert_block(struct basicblock* bb)
{
struct basicblock* outbb = pops.item[i].left;
struct ir* ir = pops.item[i].right;
struct ir* phi = new_ir0(IR_PHI, ir->size);
for (j=0; j<pushes.count; j++)
pmap_add(&phi->u.phivalue,
pushes.item[j].left,
pushes.item[j].right);
phi->root = phi;
assert(pushes.count > 0);
if (pushes.count == 1)
{
/* The push happened in exactly one place; that means we don't need a phi and can
* just import the value directly. */
*ir = *phi;
struct ir* src = pushes.item[0].right;
ir->opcode = IR_NOP;
ir->left = src;
}
else
{
/* The push could have happened in one of several places; we need a phi. */
struct ir* phi = new_ir0(IR_PHI, ir->size);
for (j=0; j<pushes.count; j++)
{
pmap_add(&phi->u.phivalue,
pushes.item[j].left,
pushes.item[j].right);
}
phi->root = phi;
*ir = *phi;
}
}
}
}