Don't treat values as signed when looking at loop steppings in HowForToNonZero.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51560 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 26010ebaa2fe3b7626d103b6d00edbb8bb58e4fd..e01cf51794efc1653654c12ef11715218f76912e 100644 (file)
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -2548,9 +2548,9 @@ SCEVHandle ScalarEvolutionsImpl::HowFarToZero(SCEV *V, const Loop *L) {
       if (SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start)) {
         ConstantInt *StartCC = StartC->getValue();
         Constant *StartNegC = ConstantExpr::getNeg(StartCC);
-        Constant *Rem = ConstantExpr::getSRem(StartNegC, StepC->getValue());
+        Constant *Rem = ConstantExpr::getURem(StartNegC, StepC->getValue());
         if (Rem->isNullValue()) {
-          Constant *Result =ConstantExpr::getSDiv(StartNegC,StepC->getValue());
+          Constant *Result = ConstantExpr::getUDiv(StartNegC,StepC->getValue());
           return SE.getUnknown(Result);
         }
       }

diff --git a/test/Analysis/ScalarEvolution/2008-05-25-NegativeStepToZero.ll b/test/Analysis/ScalarEvolution/2008-05-25-NegativeStepToZero.ll
new file mode 100644 (file)
index 0000000..922d9a9
--- /dev/null
+++ b/test/Analysis/ScalarEvolution/2008-05-25-NegativeStepToZero.ll
@@ -0,0 +1,20 @@
+; RUN: llvm-as < %s | opt -analyze -scalar-evolution | grep {61 iterations}
+
+define i32 @func_6() nounwind  {
+entry:
+       br label %bb5
+
+bb:            ; preds = %bb5
+       %tmp2 = add i32 %i.0, 1         ; <i32> [#uses=1]
+       %tmp4 = add i8 %x.0, -4         ; <i8> [#uses=1]
+       br label %bb5
+
+bb5:           ; preds = %bb, %entry
+       %x.0 = phi i8 [ 0, %entry ], [ %tmp4, %bb ]             ; <i8> [#uses=2]
+       %i.0 = phi i32 [ 0, %entry ], [ %tmp2, %bb ]            ; <i32> [#uses=2]
+       %tmp7 = icmp eq i8 %x.0, 12             ; <i1> [#uses=1]
+       br i1 %tmp7, label %return, label %bb
+
+return:                ; preds = %bb5
+       ret i32 %i.0
+}