Fold trunc casts into add-recurrence expressions, allowing the

add-recurrence to be exposed. Add a new SCEV folding rule to
help simplify expressions in the presence of these extra truncs.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71264 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 24 insertions, 0 deletions

diff --git a/test/Analysis/ScalarEvolution/trip-count4.ll b/test/Analysis/ScalarEvolution/trip-count4.ll
new file mode 100644
index 0000000..a61d5da
--- /dev/null
+++ b/test/Analysis/ScalarEvolution/trip-count4.ll
@@ -0,0 +1,24 @@
+; RUN: llvm-as < %s | opt -analyze -scalar-evolution -disable-output \
+; RUN:   | grep {sext.*trunc.*Exits: 11}
+
+; ScalarEvolution should be able to compute a loop exit value for %indvar.i8.
+
+define void @another_count_down_signed(double* %d, i64 %n) nounwind {
+entry:
+	br label %loop
+
+loop:		; preds = %loop, %entry
+	%indvar = phi i64 [ %n, %entry ], [ %indvar.next, %loop ]		; <i64> [#uses=4]
+	%s0 = shl i64 %indvar, 8		; <i64> [#uses=1]
+	%indvar.i8 = ashr i64 %s0, 8		; <i64> [#uses=1]
+	%t0 = getelementptr double* %d, i64 %indvar.i8		; <double*> [#uses=2]
+	%t1 = load double* %t0		; <double> [#uses=1]
+	%t2 = mul double %t1, 1.000000e-01		; <double> [#uses=1]
+	store double %t2, double* %t0
+	%indvar.next = sub i64 %indvar, 1		; <i64> [#uses=2]
+	%exitcond = icmp eq i64 %indvar.next, 10		; <i1> [#uses=1]
+	br i1 %exitcond, label %return, label %loop
+
+return:		; preds = %loop
+	ret void
+}