LoopVectorize fix: LoopInfo must be valid when invoking utils like SCEVExpander.

In general, one should always complete CFG modifications first, update
CFG-based analyses, like Dominatores and LoopInfo, then generate
instruction sequences.

LoopVectorizer was creating a new loop, calling SCEVExpander to
generate checks, then updating LoopInfo. I just changed the order.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186241 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 131 insertions, 18 deletions

diff --git a/lib/Transforms/Vectorize/LoopVectorize.cpp b/lib/Transforms/Vectorize/LoopVectorize.cpp
index b35ed74..0d910d1 100644
--- a/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -1476,6 +1476,22 @@ InnerLoopVectorizer::createEmptyLoop(LoopVectorizationLegality *Legal) {
   BasicBlock *ScalarPH =
   MiddleBlock->splitBasicBlock(MiddleBlock->getTerminator(), "scalar.ph");
 
+  // Create and register the new vector loop.
+  Loop* Lp = new Loop();
+  Loop *ParentLoop = OrigLoop->getParentLoop();
+
+  // Insert the new loop into the loop nest and register the new basic blocks
+  // before calling any utilities such as SCEV that require valid LoopInfo.
+  if (ParentLoop) {
+    ParentLoop->addChildLoop(Lp);
+    ParentLoop->addBasicBlockToLoop(ScalarPH, LI->getBase());
+    ParentLoop->addBasicBlockToLoop(VectorPH, LI->getBase());
+    ParentLoop->addBasicBlockToLoop(MiddleBlock, LI->getBase());
+  } else {
+    LI->addTopLevelLoop(Lp);
+  }
+  Lp->addBasicBlockToLoop(VecBody, LI->getBase());
+
   // Use this IR builder to create the loop instructions (Phi, Br, Cmp)
   // inside the loop.
   Builder.SetInsertPoint(VecBody->getFirstInsertionPt());
@@ -1530,6 +1546,8 @@ InnerLoopVectorizer::createEmptyLoop(LoopVectorizationLegality *Legal) {
     // Create a new block containing the memory check.
     BasicBlock *CheckBlock = BypassBlock->splitBasicBlock(MemRuntimeCheck,
                                                           "vector.memcheck");
+    if (ParentLoop)
+      ParentLoop->addBasicBlockToLoop(CheckBlock, LI->getBase());
     LoopBypassBlocks.push_back(CheckBlock);
 
     // Replace the branch into the memory check block with a conditional branch
@@ -1697,24 +1715,6 @@ InnerLoopVectorizer::createEmptyLoop(LoopVectorizationLegality *Legal) {
   // Get ready to start creating new instructions into the vectorized body.
   Builder.SetInsertPoint(VecBody->getFirstInsertionPt());
 
-  // Create and register the new vector loop.
-  Loop* Lp = new Loop();
-  Loop *ParentLoop = OrigLoop->getParentLoop();
-
-  // Insert the new loop into the loop nest and register the new basic blocks.
-  if (ParentLoop) {
-    ParentLoop->addChildLoop(Lp);
-    for (unsigned I = 1, E = LoopBypassBlocks.size(); I != E; ++I)
-      ParentLoop->addBasicBlockToLoop(LoopBypassBlocks[I], LI->getBase());
-    ParentLoop->addBasicBlockToLoop(ScalarPH, LI->getBase());
-    ParentLoop->addBasicBlockToLoop(VectorPH, LI->getBase());
-    ParentLoop->addBasicBlockToLoop(MiddleBlock, LI->getBase());
-  } else {
-    LI->addTopLevelLoop(Lp);
-  }
-
-  Lp->addBasicBlockToLoop(VecBody, LI->getBase());
-
   // Save the state.
   LoopVectorPreHeader = VectorPH;
   LoopScalarPreHeader = ScalarPH;
diff --git a/test/Transforms/LoopVectorize/scev-exitlim-crash.ll b/test/Transforms/LoopVectorize/scev-exitlim-crash.ll
new file mode 100644
index 0000000..5123422
--- /dev/null
+++ b/test/Transforms/LoopVectorize/scev-exitlim-crash.ll
@@ -0,0 +1,113 @@
+; RUN: opt < %s -loop-vectorize -S | FileCheck %s
+
+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-macosx"
+
+@b = common global i32 0, align 4
+@f = common global i32 0, align 4
+@a = common global i32 0, align 4
+@d = common global i32* null, align 8
+@e = common global i32* null, align 8
+@c = common global i32 0, align 4
+
+; CHECK-LABEL: @fn1
+; CHECK: vector.body
+define void @fn1() #0 {
+entry:
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.cond, %entry
+  %i.0 = phi i32 [ undef, %entry ], [ %inc, %for.cond ]
+  %cmp = icmp slt i32 %i.0, 0
+  %call = tail call i32 @fn2(double fadd (double fsub (double undef, double undef), double 1.000000e+00)) #2
+  %inc = add nsw i32 %i.0, 1
+  br i1 %cmp, label %for.cond, label %for.cond4.preheader
+
+for.cond4.preheader:                              ; preds = %for.cond
+  %call.lcssa = phi i32 [ %call, %for.cond ]
+  %cmp514 = icmp sgt i32 %call.lcssa, 0
+  br i1 %cmp514, label %for.cond7.preheader.lr.ph, label %for.end26
+
+for.cond7.preheader.lr.ph:                        ; preds = %for.cond4.preheader
+  %0 = load i32** @e, align 8, !tbaa !0
+  br label %for.cond7.preheader
+
+for.cond7.preheader:                              ; preds = %for.cond7.preheader.lr.ph, %for.inc23
+  %y.017 = phi i32 [ 0, %for.cond7.preheader.lr.ph ], [ %inc24, %for.inc23 ]
+  %i.116 = phi i32 [ 0, %for.cond7.preheader.lr.ph ], [ %i.2.lcssa, %for.inc23 ]
+  %n.015 = phi i32 [ undef, %for.cond7.preheader.lr.ph ], [ %inc25, %for.inc23 ]
+  %1 = load i32* @b, align 4, !tbaa !3
+  %tobool11 = icmp eq i32 %1, 0
+  br i1 %tobool11, label %for.inc23, label %for.body8.lr.ph
+
+for.body8.lr.ph:                                  ; preds = %for.cond7.preheader
+  %add9 = add i32 %n.015, 1
+  br label %for.body8
+
+for.body8:                                        ; preds = %for.body8.lr.ph, %for.inc19
+  %indvars.iv19 = phi i64 [ 0, %for.body8.lr.ph ], [ %indvars.iv.next20, %for.inc19 ]
+  %i.213 = phi i32 [ %i.116, %for.body8.lr.ph ], [ 0, %for.inc19 ]
+  %2 = trunc i64 %indvars.iv19 to i32
+  %add10 = add i32 %add9, %2
+  store i32 %add10, i32* @f, align 4, !tbaa !3
+  %idx.ext = sext i32 %add10 to i64
+  %add.ptr = getelementptr inbounds i32* @a, i64 %idx.ext
+  %tobool129 = icmp eq i32 %i.213, 0
+  br i1 %tobool129, label %for.inc19, label %for.body13.lr.ph
+
+for.body13.lr.ph:                                 ; preds = %for.body8
+  %3 = sext i32 %i.213 to i64
+  br label %for.body13
+
+for.body13:                                       ; preds = %for.body13.lr.ph, %for.body13
+  %indvars.iv = phi i64 [ %3, %for.body13.lr.ph ], [ %indvars.iv.next, %for.body13 ]
+  %add.ptr.sum = add i64 %idx.ext, %indvars.iv
+  %arrayidx = getelementptr inbounds i32* @a, i64 %add.ptr.sum
+  %4 = load i32* %arrayidx, align 4, !tbaa !3
+  %arrayidx15 = getelementptr inbounds i32* %0, i64 %indvars.iv
+  store i32 %4, i32* %arrayidx15, align 4, !tbaa !3
+  %indvars.iv.next = add i64 %indvars.iv, 1
+  %5 = trunc i64 %indvars.iv.next to i32
+  %tobool12 = icmp eq i32 %5, 0
+  br i1 %tobool12, label %for.cond11.for.inc19_crit_edge, label %for.body13
+
+for.cond11.for.inc19_crit_edge:                   ; preds = %for.body13
+  br label %for.inc19
+
+for.inc19:                                        ; preds = %for.cond11.for.inc19_crit_edge, %for.body8
+  %6 = load i32* @c, align 4, !tbaa !3
+  %inc20 = add nsw i32 %6, 1
+  store i32 %inc20, i32* @c, align 4, !tbaa !3
+  %indvars.iv.next20 = add i64 %indvars.iv19, 1
+  %7 = load i32* @b, align 4, !tbaa !3
+  %tobool = icmp eq i32 %7, 0
+  br i1 %tobool, label %for.cond7.for.inc23_crit_edge, label %for.body8
+
+for.cond7.for.inc23_crit_edge:                    ; preds = %for.inc19
+  %add.ptr.lcssa = phi i32* [ %add.ptr, %for.inc19 ]
+  store i32* %add.ptr.lcssa, i32** @d, align 8, !tbaa !0
+  br label %for.inc23
+
+for.inc23:                                        ; preds = %for.cond7.for.inc23_crit_edge, %for.cond7.preheader
+  %i.2.lcssa = phi i32 [ 0, %for.cond7.for.inc23_crit_edge ], [ %i.116, %for.cond7.preheader ]
+  %inc24 = add nsw i32 %y.017, 1
+  %inc25 = add nsw i32 %n.015, 1
+  %exitcond = icmp ne i32 %inc24, %call.lcssa
+  br i1 %exitcond, label %for.cond7.preheader, label %for.cond4.for.end26_crit_edge
+
+for.cond4.for.end26_crit_edge:                    ; preds = %for.inc23
+  br label %for.end26
+
+for.end26:                                        ; preds = %for.cond4.for.end26_crit_edge, %for.cond4.preheader
+  ret void
+}
+declare i32 @fn2(double) #1
+
+attributes #0 = { nounwind ssp uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf"="true" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf"="true" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!0 = metadata !{metadata !"int", metadata !1}
+!1 = metadata !{metadata !"omnipotent char", metadata !2}
+!2 = metadata !{metadata !"Simple C/C++ TBAA"}
+!3 = metadata !{metadata !"double", metadata !1}
+!4 = metadata !{metadata !"any pointer", metadata !1}