From 52937fb68506977e6b708c800b26188ed19b93b6 Mon Sep 17 00:00:00 2001
From: Ilia Mirkin <imirkin@alum.mit.edu>
Date: Sun, 28 Jun 2015 03:46:25 -0400
Subject: [PATCH] nv50/ir: keep track of how we change incoming bb order in
 PhiMovesPass

Detaching and attaching bb's will potentially change the incoming bb
order. Keep track of any such changes that happen and remap the phi node
arguments while we add mov's.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
---
 src/gallium/drivers/nouveau/codegen/nv50_ir_ra.cpp | 36 ++++++++++++++++------
 1 file changed, 26 insertions(+), 10 deletions(-)

diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_ra.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_ra.cpp
index 898653c..b51cb3e 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_ra.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_ra.cpp
@@ -360,16 +360,25 @@ RegAlloc::PhiMovesPass::visit(BasicBlock *bb)
    Instruction *phi, *mov;
    BasicBlock *pb, *pn;
 
-   std::stack<BasicBlock *> stack;
+   typedef std::pair<int, BasicBlock *> inbound;
+   std::list<inbound> edges;
+   std::list<inbound>::iterator it;
 
-   for (Graph::EdgeIterator ei = bb->cfg.incident(); !ei.end(); ei.next()) {
+   std::stack<std::list<inbound>::iterator> stack;
+
+   int j = 0;
+   for (Graph::EdgeIterator ei = bb->cfg.incident(); !ei.end(); ei.next(), ++j) {
       pb = BasicBlock::get(ei.getNode());
       assert(pb);
-      if (needNewElseBlock(bb, pb))
-         stack.push(pb);
+      edges.push_back(std::make_pair(j, pb));
+      if (needNewElseBlock(bb, pb)) {
+         it = edges.end();
+         stack.push(--it);
+      }
    }
    while (!stack.empty()) {
-      pb = stack.top();
+      it = stack.top();
+      pb = it->second;
       pn = new BasicBlock(func);
       stack.pop();
 
@@ -377,15 +386,23 @@ RegAlloc::PhiMovesPass::visit(BasicBlock *bb)
       pb->cfg.attach(&pn->cfg, Graph::Edge::TREE);
       pn->cfg.attach(&bb->cfg, Graph::Edge::FORWARD);
 
+      // Now do this same update in our inbound edge mapping. Detaching
+      // removes from the list, and attaching adds to the front.
+      j = it->first;
+      edges.erase(it);
+      edges.push_front(std::make_pair(j, pn));
+
       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)
-   int j = 0;
-   for (Graph::EdgeIterator ei = bb->cfg.incident(); !ei.end(); ei.next()) {
+   it = edges.begin();
+   for (Graph::EdgeIterator ei = bb->cfg.incident(); !ei.end(); ei.next(), ++it) {
       pb = BasicBlock::get(ei.getNode());
+      assert(it != edges.end());
+      assert(it->second == pb);
       if (!pb->isTerminated())
          pb->insertTail(new_FlowInstruction(func, OP_BRA, bb));
 
@@ -393,13 +410,12 @@ RegAlloc::PhiMovesPass::visit(BasicBlock *bb)
          LValue *tmp = new_LValue(func, phi->getDef(0)->asLValue());
          mov = new_Instruction(func, OP_MOV, typeOfSize(tmp->reg.size));
 
-         mov->setSrc(0, phi->getSrc(j));
+         mov->setSrc(0, phi->getSrc(it->first));
          mov->setDef(0, tmp);
-         phi->setSrc(j, tmp);
+         phi->setSrc(it->first, tmp);
 
          pb->insertBefore(pb->getExit(), mov);
       }
-      ++j;
    }
 
    return true;
-- 
2.3.6