From 5defea90e68e1bed10248c6535797982f8875a71 Mon Sep 17 00:00:00 2001
From: Nadav Rotem <nrotem@apple.com>
Date: Fri, 2 Aug 2013 18:40:24 +0000
Subject: [PATCH] SLPVectorizer: Fix PR16777. PHInodes may use multiple
 extracted values that come from different blocks. Thanks Alexey Samsonov.

llvm-svn: 187663
---
 llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp | 23 +++++++++-------
 llvm/test/Transforms/SLPVectorizer/X86/phi3.ll  | 35 +++++++++++++++++++++++++
 2 files changed, 48 insertions(+), 10 deletions(-)
 create mode 100644 llvm/test/Transforms/SLPVectorizer/X86/phi3.ll

diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index 60d294b..9312b4b 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -1401,30 +1401,33 @@ void BoUpSLP::vectorizeTree() {
     Value *Vec = E->VectorizedValue;
     assert(Vec && "Can't find vectorizable value");
 
+    Value *Lane = Builder.getInt32(it->Lane);
     // Generate extracts for out-of-tree users.
     // Find the insertion point for the extractelement lane.
-    Instruction *Loc = 0;
     if (PHINode *PN = dyn_cast<PHINode>(Vec)) {
-      Loc = PN->getParent()->getFirstInsertionPt();
+      Builder.SetInsertPoint(PN->getParent()->getFirstInsertionPt());
+      Value *Ex = Builder.CreateExtractElement(Vec, Lane);
+      User->replaceUsesOfWith(Scalar, Ex);
     } else if (isa<Instruction>(Vec)){
       if (PHINode *PH = dyn_cast<PHINode>(User)) {
         for (int i = 0, e = PH->getNumIncomingValues(); i != e; ++i) {
           if (PH->getIncomingValue(i) == Scalar) {
-            Loc = PH->getIncomingBlock(i)->getTerminator();
-            break;
+            Builder.SetInsertPoint(PH->getIncomingBlock(i)->getTerminator());
+            Value *Ex = Builder.CreateExtractElement(Vec, Lane);
+            PH->setOperand(i, Ex);
           }
         }
-        assert(Loc && "Unable to find incoming value for the PHI");
       } else {
-        Loc = cast<Instruction>(User);
+        Builder.SetInsertPoint(cast<Instruction>(User));
+        Value *Ex = Builder.CreateExtractElement(Vec, Lane);
+        User->replaceUsesOfWith(Scalar, Ex);
      }
     } else {
-      Loc = F->getEntryBlock().begin();
+      Builder.SetInsertPoint(F->getEntryBlock().begin());
+      Value *Ex = Builder.CreateExtractElement(Vec, Lane);
+      User->replaceUsesOfWith(Scalar, Ex);
     }
 
-    Builder.SetInsertPoint(Loc);
-    Value *Ex = Builder.CreateExtractElement(Vec, Builder.getInt32(it->Lane));
-    User->replaceUsesOfWith(Scalar, Ex);
     DEBUG(dbgs() << "SLP: Replaced:" << *User << ".\n");
   }
 
diff --git a/llvm/test/Transforms/SLPVectorizer/X86/phi3.ll b/llvm/test/Transforms/SLPVectorizer/X86/phi3.ll
new file mode 100644
index 0000000..fd8d361
--- /dev/null
+++ b/llvm/test/Transforms/SLPVectorizer/X86/phi3.ll
@@ -0,0 +1,35 @@
+; RUN: opt < %s -basicaa -slp-vectorizer -dce -S -mtriple=x86_64-apple-macosx10.8.0 -mcpu=corei7
+
+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-apple-macosx10.8.0"
+
+%struct.GPar.0.16.26 = type { [0 x double], double }
+
+@d = external global double, align 8
+
+declare %struct.GPar.0.16.26* @Rf_gpptr(...)
+
+define void @Rf_GReset() {
+entry:
+  %sub = fsub double -0.000000e+00, undef
+  %0 = load double* @d, align 8
+  %sub1 = fsub double -0.000000e+00, %0
+  br i1 icmp eq (%struct.GPar.0.16.26* (...)* inttoptr (i64 115 to %struct.GPar.0.16.26* (...)*), %struct.GPar.0.16.26* (...)* @Rf_gpptr), label %if.then, label %if.end7
+
+if.then:                                          ; preds = %entry
+  %sub2 = fsub double %sub, undef
+  %div.i = fdiv double %sub2, undef
+  %sub4 = fsub double %sub1, undef
+  %div.i16 = fdiv double %sub4, undef
+  %cmp = fcmp ogt double %div.i, %div.i16
+  br i1 %cmp, label %if.then6, label %if.end7
+
+if.then6:                                         ; preds = %if.then
+  br label %if.end7
+
+if.end7:                                          ; preds = %if.then6, %if.then, %entry
+  %g.0 = phi double [ 0.000000e+00, %if.then6 ], [ %sub, %if.then ], [ %sub, %entry ]
+  ret void
+}
+
+
-- 
2.7.4