First step to SSA construction: Phi insertion.

vm/il_printer.cc

Index: vm/il_printer.cc
===================================================================
--- vm/il_printer.cc	(revision 8546)
+++ vm/il_printer.cc	(working copy)
@@ -330,9 +330,26 @@
 
 void JoinEntryInstr::PrintTo(BufferFormatter* f) const {
   f->Print("%2d: [join]", block_id());
+  if (phis_ != NULL) {
+    for (intptr_t i = 0; i < phis_->length(); ++i) {
+      if ((*phis_)[i] == NULL) continue;
+      f->Print("\n");
+      (*phis_)[i]->PrintTo(f);
+    }
+  }
 }
 
 
+void PhiInstr::PrintTo(BufferFormatter* f) const {
+  f->Print("     phi(");
+  for (intptr_t i = 0; i < inputs_.length(); ++i) {
+    if (inputs_[i] != NULL) inputs_[i]->PrintTo(f);
+    if (i < inputs_.length() - 1) f->Print(",");
+  }
+  f->Print(")");
+}
+
+
 void TargetEntryInstr::PrintTo(BufferFormatter* f) const {
   f->Print("%2d: [target", block_id());
   if (HasTryIndex()) {
@@ -466,9 +483,21 @@
         BEGIN("states");  // Required section.
         {
           BEGIN("locals");  // Required section.
-          // TODO(fschneider): Insert phi-instructions here.
-          intptr_t num_phis = 0;
+          JoinEntryInstr* join = entry->AsJoinEntry();
+          intptr_t num_phis = (join != NULL && join->phi_count())
+              ? join->phis()->length()
+              : 0;
           Print("%s %d\n", "size", num_phis);
+          for (intptr_t j = 0; j < num_phis; ++j) {
+            PhiInstr* phi = (*join->phis())[j];
+            if (phi != NULL) {
+              Print("%d ", j);  // Print variable index.
+              char buffer[120];
+              BufferFormatter formatter(buffer, sizeof(buffer));
+              phi->PrintToVisualizer(&formatter);
+              Print("%s\n", buffer);
+            }
+          }
           END("locals");
         }
         END("states");
@@ -516,6 +545,16 @@
 }
 
 
+void PhiInstr::PrintToVisualizer(BufferFormatter* f) const {
+  // TODO(fschneider): Print operands when SSA renaming is implemented.
+  f->Print("v [");
+  for (intptr_t i = 0; i < InputCount(); ++i) {
+    f->Print(" v ");
+  }
+  f->Print("]");
+}
+
+
 void TargetEntryInstr::PrintToVisualizer(BufferFormatter* f) const {
   f->Print("_ [target");
   if (HasTryIndex()) {