From: Dan Gohman <gohman@apple.com>
Date: Wed, 24 Jun 2009 14:31:06 +0000 (+0000)
Subject: When inserting code into a loop preheader, insert it before the
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=32a81a3f6d75c5343e7df65ce5d228f2128ca943;p=oota-llvm.git

When inserting code into a loop preheader, insert it before the
terminator, instead of after the last phi. This fixes a bug
exposed by ScalarEvolution analyzing more kinds of loops.
This fixes PR4436.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74072 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp
index 658b788e0ba..ec4be9b905d 100644
--- a/lib/Transforms/Scalar/IndVarSimplify.cpp
+++ b/lib/Transforms/Scalar/IndVarSimplify.cpp
@@ -230,13 +230,16 @@ void IndVarSimplify::RewriteLoopExitValues(Loop *L,
   // We insert the code into the preheader of the loop if the loop contains
   // multiple exit blocks, or in the exit block if there is exactly one.
   BasicBlock *BlockToInsertInto;
+  BasicBlock::iterator InsertPt;
   SmallVector<BasicBlock*, 8> ExitBlocks;
   L->getUniqueExitBlocks(ExitBlocks);
-  if (ExitBlocks.size() == 1)
+  if (ExitBlocks.size() == 1) {
     BlockToInsertInto = ExitBlocks[0];
-  else
+    InsertPt = BlockToInsertInto->getFirstNonPHI();
+  } else {
     BlockToInsertInto = Preheader;
-  BasicBlock::iterator InsertPt = BlockToInsertInto->getFirstNonPHI();
+    InsertPt = BlockToInsertInto->getTerminator();
+  }
 
   std::map<Instruction*, Value*> ExitValues;
 
diff --git a/test/Transforms/IndVarSimplify/loop_evaluate7.ll b/test/Transforms/IndVarSimplify/loop_evaluate7.ll
new file mode 100644
index 00000000000..bce65e047da
--- /dev/null
+++ b/test/Transforms/IndVarSimplify/loop_evaluate7.ll
@@ -0,0 +1,61 @@
+; RUN: llvm-as < %s | opt -indvars
+; PR4436
+
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32"
+target triple = "i386-pc-linux-gnu"
+
+define i8* @string_expandtabs() nounwind {
+entry:
+	br i1 undef, label %bb33, label %bb1
+
+bb1:		; preds = %entry
+	br i1 undef, label %overflow1, label %bb15
+
+bb15:		; preds = %bb1
+	br i1 undef, label %bb33, label %bb17
+
+bb17:		; preds = %bb15
+	br label %bb30
+
+bb19:		; preds = %bb30
+	br i1 undef, label %bb20, label %bb29
+
+bb20:		; preds = %bb19
+	%0 = load i32* undef, align 4		; <i32> [#uses=1]
+	%1 = sub i32 %0, undef		; <i32> [#uses=1]
+	br label %bb23
+
+bb21:		; preds = %bb23
+	%2 = icmp ult i8* %q.0, undef		; <i1> [#uses=1]
+	br i1 %2, label %bb22, label %overflow2
+
+bb22:		; preds = %bb21
+	%3 = getelementptr i8* %q.0, i32 1		; <i8*> [#uses=1]
+	br label %bb23
+
+bb23:		; preds = %bb22, %bb20
+	%i.2 = phi i32 [ %1, %bb20 ], [ %4, %bb22 ]		; <i32> [#uses=1]
+	%q.0 = phi i8* [ undef, %bb20 ], [ %3, %bb22 ]		; <i8*> [#uses=3]
+	%4 = add i32 %i.2, -1		; <i32> [#uses=2]
+	%5 = icmp eq i32 %4, -1		; <i1> [#uses=1]
+	br i1 %5, label %bb29, label %bb21
+
+bb29:		; preds = %bb23, %bb19
+	%q.1 = phi i8* [ undef, %bb19 ], [ %q.0, %bb23 ]		; <i8*> [#uses=0]
+	br label %bb30
+
+bb30:		; preds = %bb29, %bb17
+	br i1 undef, label %bb19, label %bb33
+
+overflow2:		; preds = %bb21
+	br i1 undef, label %bb32, label %overflow1
+
+bb32:		; preds = %overflow2
+	br label %overflow1
+
+overflow1:		; preds = %bb32, %overflow2, %bb1
+	ret i8* null
+
+bb33:		; preds = %bb30, %bb15, %entry
+	ret i8* undef
+}