Using the fact that each OP_PHISOURCE is used by a single OP_PHI,
it's easier to rewrite OP_PHISOURCE at the same time as their
associated OP_PHI (because we have access to the new pseudo just created).
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
unssa.c | 89 ++++++++++++++++-------------------------------------------------
1 file changed, 21 insertions(+), 68 deletions(-)
diff --git a/unssa.c b/unssa.c
index 85b1388d..2660e94c 100644
--- a/unssa.c
+++ b/unssa.c
@@ -10,9 +10,9 @@
*
* This is similar to the "Sreedhar method I" except that the copies to the
* temporaries are not placed at the end of the predecessor basic blocks, but
- * at the place where the phi-node operands are defined (the same place where the
- * phisrc were present).
- * Is this a problem?
+ * at the place where the phi-node operands are defined.
+ * This is particulary easy since these copies are essentialy already present
+ * as the corresponding OP_PHISOURCE.
*
* While very simple this method create a lot more copies that really necessary.
* Ideally, "Sreedhar method III" should be used:
@@ -30,31 +30,35 @@
#include <assert.h>
-static void remove_phisrc_defines(struct instruction *phisrc)
-{
- struct instruction *phi;
- struct basic_block *bb = phisrc->bb;
-
- FOR_EACH_PTR(phisrc->phi_users, phi) {
- remove_pseudo(&bb->defines, phi->target);
- } END_FOR_EACH_PTR(phi);
-}
-
static void replace_phi_node(struct instruction *phi)
{
pseudo_t tmp;
+ pseudo_t p;
tmp = alloc_pseudo(NULL);
tmp->type = phi->target->type;
tmp->ident = phi->target->ident;
tmp->def = NULL; // defined by all the phisrc
-
- track_phi_uses(phi);
+ // rewrite all it's phi_src to copy to a new tmp
+ FOR_EACH_PTR(phi->phi_list, p) {
+ struct instruction *def = p->def;
+
+ if (p == VOID)
+ continue;
+
+ assert(def->opcode == OP_PHISOURCE);
+
+ def->opcode = OP_COPY;
+ def->target = tmp;
+ } END_FOR_EACH_PTR(p);
+
+ // rewrite the phi node:
+ // phi %rt, ...
+ // to:
+ // copy %rt, %tmp
phi->opcode = OP_COPY;
use_pseudo(phi, tmp, &phi->src);
-
- // FIXME: free phi->phi_list;
}
static void rewrite_phi_bb(struct basic_block *bb)
@@ -73,53 +77,6 @@ static void rewrite_phi_bb(struct basic_block *bb)
} END_FOR_EACH_PTR(insn);
}
-static void rewrite_phisrc_bb(struct basic_block *bb)
-{
- struct instruction *insn;
-
- // Replace all the phisrc by one or several copies to
- // the temporaries associated to each phi-node it defines.
- FOR_EACH_PTR_REVERSE(bb->insns, insn) {
- struct instruction *phi;
- int i;
-
- if (!insn->bb)
- continue;
- if (insn->opcode != OP_PHISOURCE)
- continue;
-
- i = 0;
- FOR_EACH_PTR(insn->phi_users, phi) {
- pseudo_t tmp = phi->src;
- pseudo_t src = insn->phi_src;
-
- if (i == 0) { // first phi: we overwrite the phisrc
- insn->opcode = OP_COPY;
- insn->target = tmp;
- insn->src = src;
- } else {
- struct instruction *copy = __alloc_instruction(0);
-
- copy->bb = bb;
- copy->opcode = OP_COPY;
- copy->size = insn->size;
- copy->pos = insn->pos;
- copy->target = tmp;
- copy->src = src;
-
- INSERT_CURRENT(copy, insn);
- }
- // update the liveness info
- remove_phisrc_defines(insn);
- // FIXME: should really something like add_pseudo_exclusive()
- add_pseudo(&bb->defines, tmp);
-
- i++;
- } END_FOR_EACH_PTR(phi);
-
- } END_FOR_EACH_PTR_REVERSE(insn);
-}
-
int unssa(struct entrypoint *ep)
{
struct basic_block *bb;
@@ -128,9 +85,5 @@ int unssa(struct entrypoint *ep)
rewrite_phi_bb(bb);
} END_FOR_EACH_PTR(bb);
- FOR_EACH_PTR(ep->bbs, bb) {
- rewrite_phisrc_bb(bb);
- } END_FOR_EACH_PTR(bb);
-
return 0;
}
--
2.10.2
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