From d4e7f44319824998bafe1bd1c50314e1310a9ca1 Mon Sep 17 00:00:00 2001
From: Devang Patel <dpatel@apple.com>
Date: Mon, 10 Nov 2008 19:48:34 +0000
Subject: [PATCH] If the sign of exit condition and split condition does not
 match then do not split loop index.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58995 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/LoopIndexSplit.cpp      |  7 +-
 .../LoopIndexSplit/2008-11-10-Sign.ll         | 69 +++++++++++++++++++
 2 files changed, 75 insertions(+), 1 deletion(-)
 create mode 100644 test/Transforms/LoopIndexSplit/2008-11-10-Sign.ll

diff --git a/lib/Transforms/Scalar/LoopIndexSplit.cpp b/lib/Transforms/Scalar/LoopIndexSplit.cpp
index 9a5920c8b97..8c54ce372ee 100644
--- a/lib/Transforms/Scalar/LoopIndexSplit.cpp
+++ b/lib/Transforms/Scalar/LoopIndexSplit.cpp
@@ -1437,7 +1437,12 @@ bool LoopIndexSplit::splitLoop(SplitInfo &SD) {
     if (ICMP->getPredicate() == ICmpInst::ICMP_EQ)
       return false;
   }
-  
+
+  // If the predicate sign does not match then skip.
+  ICmpInst *CI = dyn_cast<ICmpInst>(SD.SplitCondition);
+  if (CI && (ExitCondition->isSignedPredicate() != CI->isSignedPredicate()))
+    return false;
+
   BasicBlock *SplitCondBlock = SD.SplitCondition->getParent();
   
   // Unable to handle triangle loops at the moment.
diff --git a/test/Transforms/LoopIndexSplit/2008-11-10-Sign.ll b/test/Transforms/LoopIndexSplit/2008-11-10-Sign.ll
new file mode 100644
index 00000000000..11ee0f5c452
--- /dev/null
+++ b/test/Transforms/LoopIndexSplit/2008-11-10-Sign.ll
@@ -0,0 +1,69 @@
+; RUN: llvm-as < %s | opt -loop-index-split -stats | not grep "loop-index-split"
+; PR3029
+
+@g_138 = common global i32 0		; <i32*> [#uses=3]
+@g_188 = common global i32 0		; <i32*> [#uses=4]
+@g_207 = common global i32 0		; <i32*> [#uses=3]
+@"\01LC" = internal constant [4 x i8] c"%d\0A\00"		; <[4 x i8]*> [#uses=1]
+@g_102 = common global i32 0		; <i32*> [#uses=0]
+
+define i32 @func_119() nounwind {
+entry:
+	%0 = volatile load i32* @g_138, align 4		; <i32> [#uses=1]
+	ret i32 %0
+}
+
+define void @func_110(i32 %p_111) nounwind {
+entry:
+	%0 = load i32* @g_188, align 4		; <i32> [#uses=1]
+	%1 = icmp ugt i32 %0, -1572397472		; <i1> [#uses=1]
+	br i1 %1, label %bb, label %bb1
+
+bb:		; preds = %entry
+	%2 = volatile load i32* @g_138, align 4		; <i32> [#uses=0]
+	ret void
+
+bb1:		; preds = %entry
+	store i32 1, i32* @g_207, align 4
+	ret void
+}
+
+define void @func_34() nounwind {
+entry:
+	store i32 0, i32* @g_188
+	%g_188.promoted = load i32* @g_188		; <i32> [#uses=1]
+	br label %bb
+
+bb:		; preds = %func_110.exit, %entry
+	%g_188.tmp.0 = phi i32 [ %g_188.promoted, %entry ], [ %2, %func_110.exit ]		; <i32> [#uses=2]
+	%0 = icmp ugt i32 %g_188.tmp.0, -1572397472		; <i1> [#uses=1]
+	br i1 %0, label %bb.i, label %bb1.i
+
+bb.i:		; preds = %bb
+	%1 = volatile load i32* @g_138, align 4		; <i32> [#uses=0]
+	br label %func_110.exit
+
+bb1.i:		; preds = %bb
+	store i32 1, i32* @g_207, align 4
+	br label %func_110.exit
+
+func_110.exit:		; preds = %bb.i, %bb1.i
+	%2 = add i32 %g_188.tmp.0, 1		; <i32> [#uses=3]
+	%3 = icmp sgt i32 %2, 1		; <i1> [#uses=1]
+	br i1 %3, label %return, label %bb
+
+return:		; preds = %func_110.exit
+	%.lcssa = phi i32 [ %2, %func_110.exit ]		; <i32> [#uses=1]
+	store i32 %.lcssa, i32* @g_188
+	ret void
+}
+
+define i32 @main() nounwind {
+entry:
+	call void @func_34() nounwind
+	%0 = load i32* @g_207, align 4		; <i32> [#uses=1]
+	%1 = call i32 (i8*, ...)* @printf(i8* getelementptr ([4 x i8]* @"\01LC", i32 0, i32 0), i32 %0) nounwind		; <i32> [#uses=0]
+	ret i32 0
+}
+
+declare i32 @printf(i8*, ...) nounwind