[PATCH] D16611: Fix CombineToPreIndexedLoadStore O(n^2) behavior

[Tim Shen via llvm-commits]

timshen updated this revision to Diff 46355.
timshen added a comment.

Update format and comment.


http://reviews.llvm.org/D16611

Files:
  lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  lib/CodeGen/SelectionDAG/SelectionDAG.cpp
  test/CodeGen/PowerPC/combine-to-pre-index-store-crash.ll

Index: test/CodeGen/PowerPC/combine-to-pre-index-store-crash.ll
===================================================================
--- /dev/null
+++ test/CodeGen/PowerPC/combine-to-pre-index-store-crash.ll
@@ -0,0 +1,20 @@
+; RUN: llc < %s
+target datalayout = "e-m:e-i64:64-n32:64"
+target triple = "powerpc64le-grtev4-linux-gnu"
+
+%StructA = type <{ i64, { i64, i64 }, { i64, i64 } }>
+
+define void @TestFoo(%StructA* %this) {
+  %tmp = getelementptr inbounds %StructA, %StructA* %this, i64 0, i32 1
+  %tmp11 = getelementptr inbounds %StructA, %StructA* %this, i64 0, i32 1, i32 1
+  %tmp12 = bitcast { i64, i64 }* %tmp to i64**
+  store i64* %tmp11, i64** %tmp12
+  call void @TestBar()
+  %tmp13 = getelementptr inbounds %StructA, %StructA* %this, i64 0, i32 2, i32 1
+  store i64* %tmp13, i64** undef
+  %.cast.i.i.i = bitcast i64* %tmp13 to i8*
+  store i8 0, i8* %.cast.i.i.i
+  ret void
+}
+
+declare void @TestBar()
Index: lib/CodeGen/SelectionDAG/SelectionDAG.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -6949,13 +6949,16 @@
   // Haven't visited N yet. Continue the search.
   while (!Worklist.empty()) {
     const SDNode *M = Worklist.pop_back_val();
+    bool Found = false;
     for (const SDValue &OpV : M->op_values()) {
       SDNode *Op = OpV.getNode();
       if (Visited.insert(Op).second)
         Worklist.push_back(Op);
       if (Op == N)
-        return true;
+        Found = true;
     }
+    if (Found)
+      return true;
   }
 
   return false;
Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -9593,6 +9593,10 @@
       return false;
   }
 
+  // Caches for hasPredecessorHelper.
+  SmallPtrSet<const SDNode *, 32> Visited;
+  SmallVector<const SDNode *, 16> Worklist;
+
   // If the offset is a constant, there may be other adds of constants that
   // can be folded with this one. We should do this to avoid having to keep
   // a copy of the original base pointer.
@@ -9607,7 +9611,7 @@
       if (Use.getUser() == Ptr.getNode() || Use != BasePtr)
         continue;
 
-      if (Use.getUser()->isPredecessorOf(N))
+      if (N->hasPredecessorHelper(Use.getUser(), Visited, Worklist))
         continue;
 
       if (Use.getUser()->getOpcode() != ISD::ADD &&
@@ -9637,10 +9641,6 @@
   // Now check for #3 and #4.
   bool RealUse = false;
 
-  // Caches for hasPredecessorHelper
-  SmallPtrSet<const SDNode *, 32> Visited;
-  SmallVector<const SDNode *, 16> Worklist;
-
   for (SDNode *Use : Ptr.getNode()->uses()) {
     if (Use == N)
       continue;


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