Build the correct range for loops with unusual bounds. Fix from Jay Foad.

llvm-svn: 42394

2 files changed, 22 insertions, 1 deletions

diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index aaba49eacd9..069f6ec714c 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -2470,7 +2470,7 @@ SCEVHandle SCEVAddRecExpr::getNumIterationsInRange(ConstantRange Range) const {
     APInt End = A.sge(One) ? (Range.getUpper() - One) : Range.getLower();
 
     // The exit value should be (End+A)/A.
-    APInt ExitVal = (End + A).sdiv(A);
+    APInt ExitVal = (End + A).udiv(A);
     ConstantInt *ExitValue = ConstantInt::get(ExitVal);
 
     // Evaluate at the exit value.  If we really did fall out of the valid
diff --git a/llvm/test/Analysis/ScalarEvolution/2007-09-27-LargeStepping.ll b/llvm/test/Analysis/ScalarEvolution/2007-09-27-LargeStepping.ll
new file mode 100644
index 00000000000..d7a0bafe5d6
--- /dev/null
+++ b/llvm/test/Analysis/ScalarEvolution/2007-09-27-LargeStepping.ll
@@ -0,0 +1,21 @@
+; RUN: llvm-as < %s | opt -analyze -scalar-evolution 2>&1 | grep "13 iterations"
+; PR1706
+
+define i32 @f() {
+entry:
+	br label %bb5
+
+bb:		; preds = %bb5
+	%tmp2 = shl i32 %j.0, 1		; <i32> [#uses=1]
+	%tmp4 = add i32 %i.0, 268435456		; <i32> [#uses=1]
+	br label %bb5
+
+bb5:		; preds = %bb, %entry
+	%j.0 = phi i32 [ 1, %entry ], [ %tmp2, %bb ]		; <i32> [#uses=2]
+	%i.0 = phi i32 [ -1879048192, %entry ], [ %tmp4, %bb ]		; <i32> [#uses=2]
+	%tmp7 = icmp slt i32 %i.0, 1610612736		; <i1> [#uses=1]
+	br i1 %tmp7, label %bb, label %return
+
+return:		; preds = %bb5
+	ret i32 %j.0
+}