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Reenable eviction of corrupted registers, which had been broken by a previous

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change. Change the register move code to get swaps right, or at least righter.
This commit is contained in:
David Given 2016-11-15 21:55:10 +01:00
parent 86c832ef86
commit 581fa4a457
1 changed files with 33 additions and 12 deletions
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39
mach/proto/mcg/pass_registerallocator.c
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@ -347,13 +347,11 @@ static void add_through_register(struct vreg* vreg, struct hreg* hreg)
if (hreg)
{
bool unusedin = allocatable_stackable_input(hreg, vreg);
bool unusedout = allocatable_stackable_output(hreg, vreg);
bool unused = allocatable_through(hreg, vreg);
struct vreg* inuse = pmap_findleft(current_ins, hreg);
struct vreg* outuse = pmap_findleft(current_outs, hreg);
if ((unusedin || (inuse == vreg)) &&
(unusedout || (outuse == vreg)))
if (unused || ((inuse == vreg) && (outuse == vreg)))
{
/* Input and output are either free or already assigned to this
* vreg. */
@ -594,7 +592,6 @@ static int insert_moves(struct basicblock* bb, int index,
struct hreg* src = pmap_findright(srcregs, vreg);
assert(src != NULL);
if (src != dest)
pmap_add(&copies, src, dest);
}
@ -602,7 +599,7 @@ static int insert_moves(struct basicblock* bb, int index,
{
struct hreg* src;
struct hreg* dest;
struct hreg* temp;
struct hreg* other;
struct hop* hop;
/* Try and find a destination which isn't a source. */
@ -627,14 +624,38 @@ static int insert_moves(struct basicblock* bb, int index,
}
else
{
/* There's nowhere to copy to --- the copies that are left form a cycle.
* So we need to swap instead. */
/* Okay, so there's nowhere to free to move src to. This could be
* because it's already in the right place. */
src = copies.item[0].left;
dest = pmap_findleft(&copies, src);
if (src == dest)
{
/* This register is already in the right place! */
pmap_remove(&copies, src, dest);
continue;
}
else
{
/* It's not in the right place. That means we have a cycle, and need to do
* a swap. */
/* (src->dest, other->src) */
hop = platform_swap(bb, src, dest);
pmap_remove(&copies, src, dest);
pmap_remove(&copies, dest, src);
/* Now src and dest are swapped. We know that the old src is in the right place
* and now contains dest. Any copies from the old dest (now containing src) must
* be patched to point at the old src. */
for (i=0; i<copies.count; i++)
{
if (copies.item[i].right == src)
copies.item[i].right = dest;
}
}
}
array_insert(&bb->hops, hop, index + inserted);