From c9400316fd5c993e94b76d2a63a7740209289ced Mon Sep 17 00:00:00 2001
From: Joel Dice <git@seibutsu.mailsnare.net>
Date: Mon, 16 Mar 2009 20:03:59 -0600
Subject: [PATCH] try harder to find a suitable stack frame site in pickTarget
 when there are no free registers left

---
 src/compiler.cpp | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/src/compiler.cpp b/src/compiler.cpp
index 74af58d4bf..f48fa446a6 100644
--- a/src/compiler.cpp
+++ b/src/compiler.cpp
@@ -1153,7 +1153,7 @@ pickFrameTarget(Context* c, Value* v)
   do {
     if (p->home >= 0) {
       Target mine(p->home, MemoryOperand, frameCost(c, v, p->home));
-      if (mine.cost == 0) {
+      if (mine.cost == 1) {
         return mine;
       } else if (mine.cost < best.cost) {
         best = mine;
@@ -1165,6 +1165,24 @@ pickFrameTarget(Context* c, Value* v)
   return best;
 }
 
+Target
+pickAnyFrameTarget(Context* c, Value* v)
+{
+  Target best;
+
+  unsigned count = usableFrameSize(c) + c->parameterFootprint;
+  for (unsigned i = 0; i < count; ++i) {
+    Target mine(i, MemoryOperand, frameCost(c, v, i));
+    if (mine.cost == 1) {
+      return mine;
+    } else if (mine.cost < best.cost) {
+      best = mine;
+    }    
+  }
+
+  return best;
+}
+
 Target
 pickTarget(Context* c, Read* read, bool intersectRead,
            unsigned registerReserveCount)
@@ -1221,6 +1239,14 @@ pickTarget(Context* c, Read* read, bool intersectRead,
     }
   }
 
+  if (best.cost > 3 and c->availableRegisterCount == 0) {
+    // there are no free registers left, so moving from memory to
+    // memory isn't an option - try harder to find an available frame
+    // site:
+    best = pickAnyFrameTarget(c, read->value);
+    assert(c, best.cost <= 3);
+  }
+
   return best;
 }