From mboxrd@z Thu Jan 1 00:00:00 1970 From: bugzilla-daemon-CC+yJ3UmIYqDUpFQwHEjaQ@public.gmane.org Subject: [Bug 90887] PhiMovesPass in register allocator broken Date: Sun, 28 Jun 2015 06:17:58 +0000 Message-ID: References: Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0375236360==" Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: nouveau-bounces-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org Sender: "Nouveau" To: nouveau-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org List-Id: nouveau.vger.kernel.org --===============0375236360== Content-Type: multipart/alternative; boundary="1435472277.225BfD0F1.21193"; charset="UTF-8" --1435472277.225BfD0F1.21193 Date: Sun, 28 Jun 2015 06:17:57 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" https://bugs.freedesktop.org/show_bug.cgi?id=90887 --- Comment #14 from Ilia Mirkin --- OK, so among other changes, commit e43a3a66 had the following diff: @@ -312,23 +337,26 @@ RegAlloc::PhiMovesPass::visit(BasicBlock *bb) Instruction *phi, *mov; BasicBlock *pb, *pn; + std::stack stack; + for (Graph::EdgeIterator ei = bb->cfg.incident(); !ei.end(); ei.next()) { - pb = pn = BasicBlock::get(ei.getNode()); + pb = BasicBlock::get(ei.getNode()); assert(pb); - - if (needNewElseBlock(bb, pb)) { - pn = new BasicBlock(func); - - // deletes an edge, iterator is invalid after this: - pb->cfg.detach(&bb->cfg); - pb->cfg.attach(&pn->cfg, Graph::Edge::TREE); - pn->cfg.attach(&bb->cfg, Graph::Edge::FORWARD); // XXX: check order ! - - assert(pb->getExit()->op != OP_CALL); - if (pb->getExit()->asFlow()->target.bb == bb) - pb->getExit()->asFlow()->target.bb = pn; - break; - } + if (needNewElseBlock(bb, pb)) + stack.push(pb); + } + while (!stack.empty()) { + pb = stack.top(); + pn = new BasicBlock(func); + stack.pop(); + + pb->cfg.detach(&bb->cfg); + pb->cfg.attach(&pn->cfg, Graph::Edge::TREE); + pn->cfg.attach(&bb->cfg, Graph::Edge::FORWARD); + + assert(pb->getExit()->op != OP_CALL); + if (pb->getExit()->asFlow()->target.bb == bb) + pb->getExit()->asFlow()->target.bb = pn; } // insert MOVs (phi->src(j) should stem from j-th in-BB) which the patch in attachment 116339 effectively undoes. [Why was that in there? No idea. But presumably futzing with bb's affects needNewElseBlock's decisions.] So I'm still tending towards my solution. But I'm not particularly happy that it has to build up and use that hash table every time even if nothing's changed. -- You are receiving this mail because: You are the QA Contact for the bug. You are the assignee for the bug. --1435472277.225BfD0F1.21193 Date: Sun, 28 Jun 2015 06:17:57 +0000 MIME-Version: 1.0 Content-Type: text/html; charset="UTF-8"

Comment # 14 on bug 90887 from 
OK, so among other changes, commit e43a3a66 had the following diff:

@@ -312,23 +337,26 @@ RegAlloc::PhiMovesPass::visit(BasicBlock *bb)
    Instruction *phi, *mov;
    BasicBlock *pb, *pn;

+   std::stack<BasicBlock *> stack;
+
    for (Graph::EdgeIterator ei = bb->cfg.incident(); !ei.end(); ei.next()) {
-      pb = pn = BasicBlock::get(ei.getNode());
+      pb = BasicBlock::get(ei.getNode());
       assert(pb);
-
-      if (needNewElseBlock(bb, pb)) {
-         pn = new BasicBlock(func);
-
-         // deletes an edge, iterator is invalid after this:
-         pb->cfg.detach(&bb->cfg);
-         pb->cfg.attach(&pn->cfg, Graph::Edge::TREE);
-         pn->cfg.attach(&bb->cfg, Graph::Edge::FORWARD); // XXX: check order !
-
-         assert(pb->getExit()->op != OP_CALL);
-         if (pb->getExit()->asFlow()->target.bb == bb)
-            pb->getExit()->asFlow()->target.bb = pn;
-         break;
-      }
+      if (needNewElseBlock(bb, pb))
+         stack.push(pb);
+   }
+   while (!stack.empty()) {
+      pb = stack.top();
+      pn = new BasicBlock(func);
+      stack.pop();
+
+      pb->cfg.detach(&bb->cfg);
+      pb->cfg.attach(&pn->cfg, Graph::Edge::TREE);
+      pn->cfg.attach(&bb->cfg, Graph::Edge::FORWARD);
+
+      assert(pb->getExit()->op != OP_CALL);
+      if (pb->getExit()->asFlow()->target.bb == bb)
+         pb->getExit()->asFlow()->target.bb = pn;
    }

    // insert MOVs (phi->src(j) should stem from j-th in-BB)

which the patch in attachment 116339 [details] effectively undoes. [Why was that in
there? No idea. But presumably futzing with bb's affects needNewElseBlock's
decisions.] So I'm still tending towards my solution. But I'm not particularly
happy that it has to build up and use that hash table every time even if
nothing's changed.

You are receiving this mail because:
  • You are the QA Contact for the bug.
  • You are the assignee for the bug.
--1435472277.225BfD0F1.21193-- --===============0375236360== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KTm91dmVhdSBt YWlsaW5nIGxpc3QKTm91dmVhdUBsaXN0cy5mcmVlZGVza3RvcC5vcmcKaHR0cDovL2xpc3RzLmZy ZWVkZXNrdG9wLm9yZy9tYWlsbWFuL2xpc3RpbmZvL25vdXZlYXUK --===============0375236360==--