// Compute the two solutions for the quadratic formula.
// The divisions must be performed as signed divisions.
APInt NegB(-B);
- APInt TwoA( A << 1 );
+ APInt TwoA(A << 1);
if (TwoA.isMinValue()) {
const SCEV *CNC = SE.getCouldNotCompute();
return std::make_pair(CNC, CNC);
return std::make_pair(SE.getConstant(Solution1),
SE.getConstant(Solution2));
- } // end APIntOps namespace
+ } // end APIntOps namespace
}
/// HowFarToZero - Return the number of times a backedge comparing the specified
// Handle unitary steps, which cannot wraparound.
// 1*N = -Start; -1*N = Start (mod 2^BW), so:
// N = Distance (as unsigned)
- if (StepC->getValue()->equalsInt(1) || StepC->getValue()->isAllOnesValue())
- return Distance;
+ if (StepC->getValue()->equalsInt(1) || StepC->getValue()->isAllOnesValue()) {
+ ConstantRange CR = getUnsignedRange(Start);
+ const SCEV *MaxBECount = getConstant(CountDown ? CR.getUnsignedMax()
+ : ~CR.getUnsignedMin());
+ return ExitLimit(Distance, MaxBECount);
+ }
// If the recurrence is known not to wraparound, unsigned divide computes the
// back edge count. We know that the value will either become zero (and thus
}
declare i32 @printf(i8*, ...)
+
+define void @test(i8* %a, i32 %n) nounwind {
+entry:
+ %cmp1 = icmp sgt i32 %n, 0
+ br i1 %cmp1, label %for.body.lr.ph, label %for.end
+
+for.body.lr.ph: ; preds = %entry
+ %tmp = zext i32 %n to i64
+ br label %for.body
+
+for.body: ; preds = %for.body, %for.body.lr.ph
+ %indvar = phi i64 [ %indvar.next, %for.body ], [ 0, %for.body.lr.ph ]
+ %arrayidx = getelementptr i8* %a, i64 %indvar
+ store i8 0, i8* %arrayidx, align 1
+ %indvar.next = add i64 %indvar, 1
+ %exitcond = icmp ne i64 %indvar.next, %tmp
+ br i1 %exitcond, label %for.body, label %for.cond.for.end_crit_edge
+
+for.cond.for.end_crit_edge: ; preds = %for.body
+ br label %for.end
+
+for.end: ; preds = %for.cond.for.end_crit_edge, %entry
+ ret void
+}
+
+; CHECK: Determining loop execution counts for: @test
+; CHECK-NEXT: backedge-taken count is
+; CHECK-NEXT: max backedge-taken count is -1