From 2ca24f83c35b253593b5aa8775d37923c8383149 Mon Sep 17 00:00:00 2001
From: lemon <lsof@mailbox.org>
Date: Sat, 3 Jun 2023 21:51:28 +0200
Subject: abi lowering pass

---
 regalloc.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

(limited to 'regalloc.c')

diff --git a/regalloc.c b/regalloc.c
index 338d6a6..6200d0f 100644
--- a/regalloc.c
+++ b/regalloc.c
@@ -36,7 +36,7 @@ use(struct block *blk, enum op op, int hint, union ref *ref)
 {
    struct instr *ins;
    if (ref->t == RMORE) {
-      if (op == Ocall || op == Obuiltin) {
+      if (op == Ocall || op == Ointrin) {
          struct call *call = &calltab.p[ref->idx];
          for (int i = 0; i < call->narg; ++i)
             use(blk, 0, 0, &call->args[i]);
@@ -57,7 +57,17 @@ use(struct block *blk, enum op op, int hint, union ref *ref)
             /* result of comparison instr is only used to conditionally branch,
              * doesn't usually need a reg (handled by isel) */
             return;
-      if (hint != -1) {
+      /* TODO implement actual constraints and stuff */
+      if (ins->op == Ocall) {
+         struct call *call = &calltab.p[ins->r.idx];
+         hint = call->abiret[0].reg;
+      } else if (ins->op == Ocall2r) {
+         struct instr *ins2 = &instrtab[ins->l.idx];
+         struct call *call = &calltab.p[ins2->r.idx];
+         assert(ins->l.t == RTMP && ins2->op == Ocall);
+         hint = call->abiret[0].reg;
+      }
+      if (hint != -1 && !bstest(taken, hint)) {
          bsset(taken, hint);
          ins->reg = hint + 1;
       } else {
@@ -92,10 +102,12 @@ regalloc(struct function *fn)
          use(blk, Ophi, ins->reg - 1, &ins->l);
       }
       for (int i = blk->ins.n - 1; i >= 0; --i) {
+         int hint0 = -1, hint1 = -1;
          ins = &instrtab[blk->ins.p[i]];
          def(ins);
-         if (ins->l.t) use(blk, ins->op, -1, &ins->l);
-         if (ins->r.t) use(blk, ins->op, -1, &ins->r);
+         if (ins->op == Ocopy) hint0 = ins->reg - 1;
+         if (ins->l.t) use(blk, ins->op, hint0, &ins->l);
+         if (ins->r.t) use(blk, ins->op, hint1, &ins->r);
       }
    } while ((blk = blk->lprev) != last);
 }
-- 
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