Fix SSAUpdaterImpl's RecordMatchingPHI to record exactly the

PHI nodes which were matched, rather than climbing up the
original PHI node's operands to rediscover PHI nodes for
recording, since the PHI nodes found that are not
necessarily part of the matched set.
This fixes rdar://10589171.

llvm-svn: 149654

2 files changed, 88 insertions, 32 deletions

diff --git a/llvm/include/llvm/Transforms/Utils/SSAUpdaterImpl.h b/llvm/include/llvm/Transforms/Utils/SSAUpdaterImpl.h
index 15d65bcf8c6..a9adbd73c15 100644
--- a/llvm/include/llvm/Transforms/Utils/SSAUpdaterImpl.h
+++ b/llvm/include/llvm/Transforms/Utils/SSAUpdaterImpl.h
@@ -380,7 +380,7 @@ public:
       if (!SomePHI)
         break;
       if (CheckIfPHIMatches(SomePHI)) {
-        RecordMatchingPHI(SomePHI);
+        RecordMatchingPHIs(BlockList);
         break;
       }
       // Match failed: clear all the PHITag values.
@@ -437,38 +437,17 @@ public:
     return true;
   }
 
-  /// RecordMatchingPHI - For a PHI node that matches, record it and its input
-  /// PHIs in both the BBMap and the AvailableVals mapping.
-  void RecordMatchingPHI(PhiT *PHI) {
-    SmallVector<PhiT*, 20> WorkList;
-    WorkList.push_back(PHI);
-
-    // Record this PHI.
-    BlkT *BB = PHI->getParent();
-    ValT PHIVal = Traits::GetPHIValue(PHI);
-    (*AvailableVals)[BB] = PHIVal;
-    BBMap[BB]->AvailableVal = PHIVal;
-
-    while (!WorkList.empty()) {
-      PHI = WorkList.pop_back_val();
-
-      // Iterate through the PHI's incoming values.
-      for (typename Traits::PHI_iterator I = Traits::PHI_begin(PHI),
-             E = Traits::PHI_end(PHI); I != E; ++I) {
-        ValT IncomingVal = I.getIncomingValue();
-        PhiT *IncomingPHI = Traits::ValueIsPHI(IncomingVal, Updater);
-        if (!IncomingPHI) continue;
-        BB = IncomingPHI->getParent();
-        BBInfo *Info = BBMap[BB];
-        if (!Info || Info->AvailableVal)
-          continue;
-
-        // Record the PHI and add it to the worklist.
-        (*AvailableVals)[BB] = IncomingVal;
-        Info->AvailableVal = IncomingVal;
-        WorkList.push_back(IncomingPHI);
+  /// RecordMatchingPHIs - For each PHI node that matches, record it in both
+  /// the BBMap and the AvailableVals mapping.
+  void RecordMatchingPHIs(BlockListTy *BlockList) {
+    for (typename BlockListTy::iterator I = BlockList->begin(),
+           E = BlockList->end(); I != E; ++I)
+      if (PhiT *PHI = (*I)->PHITag) {
+        BlkT *BB = PHI->getParent();
+        ValT PHIVal = Traits::GetPHIValue(PHI);
+        (*AvailableVals)[BB] = PHIVal;
+        BBMap[BB]->AvailableVal = PHIVal;
       }
-    }
   }
 };
 
diff --git a/llvm/test/Transforms/ScalarRepl/phi-cycle.ll b/llvm/test/Transforms/ScalarRepl/phi-cycle.ll
new file mode 100644
index 00000000000..cb5101c2dd8
--- /dev/null
+++ b/llvm/test/Transforms/ScalarRepl/phi-cycle.ll
@@ -0,0 +1,77 @@
+; RUN: opt -S -scalarrepl-ssa < %s | FileCheck %s
+; rdar://10589171
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+%struct.foo = type { i32, i32 }
+
+@.str = private unnamed_addr constant [6 x i8] c"x=%d\0A\00", align 1
+
+define i32 @main(i32 %argc, i8** nocapture %argv) nounwind uwtable {
+entry:
+  %f = alloca %struct.foo, align 4
+  %x.i = getelementptr inbounds %struct.foo* %f, i64 0, i32 0
+  store i32 1, i32* %x.i, align 4
+  %y.i = getelementptr inbounds %struct.foo* %f, i64 0, i32 1
+  br label %while.cond.i
+
+; CHECK: while.cond.i:
+; CHECK-NEXT: %tmp = phi i32 [ 1, %entry ], [ %tmp2, %while.cond.backedge.i ]
+; CHECK-NEXT: %pos.0.i = phi i32 [ 1, %entry ], [ %xtmp.i, %while.cond.backedge.i ]
+; CHECK-NEXT: %left.0.i = phi i32 [ 1, %entry ], [ %dec.i, %while.cond.backedge.i ]
+; CHECK-NOT: phi
+while.cond.i:                                     ; preds = %while.cond.backedge.i, %entry
+  %tmp = phi i32 [ 1, %entry ], [ %tmp2, %while.cond.backedge.i ]
+  %pos.0.i = phi i32 [ 1, %entry ], [ %xtmp.i, %while.cond.backedge.i ]
+  %left.0.i = phi i32 [ 1, %entry ], [ %dec.i, %while.cond.backedge.i ]
+  %cmp.i = icmp sgt i32 %left.0.i, 0
+  br i1 %cmp.i, label %while.body.i, label %while.cond.i.func.exit_crit_edge
+
+while.cond.i.func.exit_crit_edge:                 ; preds = %while.cond.i
+  br label %func.exit
+
+while.body.i:                                     ; preds = %while.cond.i
+  %dec.i = add nsw i32 %left.0.i, -1
+  switch i32 1, label %while.body.i.func.exit_crit_edge [
+    i32 0, label %while.cond.backedge.i
+    i32 1, label %sw.bb.i
+  ]
+
+while.body.i.func.exit_crit_edge:                 ; preds = %while.body.i
+  br label %func.exit
+
+sw.bb.i:                                          ; preds = %while.body.i
+  %cmp2.i = icmp eq i32 %tmp, 1
+  br i1 %cmp2.i, label %if.then.i, label %if.end.i
+
+if.then.i:                                        ; preds = %sw.bb.i
+  store i32 %pos.0.i, i32* %x.i, align 4
+  br label %if.end.i
+
+; CHECK: if.end.i:
+; CHECK-NEXT: %tmp1 = phi i32 [ %pos.0.i, %if.then.i ], [ %tmp, %sw.bb.i ]
+; CHECK-NOT: phi
+if.end.i:                                         ; preds = %if.then.i, %sw.bb.i
+  %tmp1 = phi i32 [ %pos.0.i, %if.then.i ], [ %tmp, %sw.bb.i ]
+  store i32 %tmp1, i32* %y.i, align 4
+  br label %while.cond.backedge.i
+
+; CHECK: while.cond.backedge.i:
+; CHECK-NEXT: %tmp2 = phi i32 [ %tmp1, %if.end.i ], [ %tmp, %while.body.i ]
+; CHECK-NOT: phi
+while.cond.backedge.i:                            ; preds = %if.end.i, %while.body.i
+  %tmp2 = phi i32 [ %tmp1, %if.end.i ], [ %tmp, %while.body.i ]
+  %xtmp.i = add i32 %pos.0.i, 1
+  br label %while.cond.i
+
+; CHECK: func.exit:
+; CHECK-NOT: load
+; CHECK: %call = call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([6 x i8]* @.str, i64 0, i64 0), i32 %tmp) nounwind
+func.exit:                                        ; preds = %while.body.i.func.exit_crit_edge, %while.cond.i.func.exit_crit_edge
+  %tmp3 = load i32* %x.i, align 4
+  %call = call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([6 x i8]* @.str, i64 0, i64 0), i32 %tmp3) nounwind
+  ret i32 0
+}
+
+declare i32 @printf(i8* nocapture, ...) nounwind