1 files changed, 79 insertions, 0 deletions
diff --git a/test/Transforms/LoopVectorize/reverse_induction.ll b/test/Transforms/LoopVectorize/reverse_induction.ll
new file mode 100644
index 0000000..f43f02b
--- /dev/null
+++ b/test/Transforms/LoopVectorize/reverse_induction.ll
@@ -0,0 +1,79 @@
+; RUN: opt < %s -loop-vectorize -force-vector-unroll=2 -force-vector-width=4 -S | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+
+; Make sure consecutive vector generates correct negative indices.
+; PR15882
+
+; CHECK: reverse_induction_i64
+; CHECK: add <4 x i64> %[[SPLAT:.*]], <i64 0, i64 -1, i64 -2, i64 -3>
+; CHECK: add <4 x i64> %[[SPLAT]], <i64 -4, i64 -5, i64 -6, i64 -7>
+
+define i32 @reverse_induction_i64(i64 %startval, i32 * %ptr) {
+entry:
+  br label %for.body
+
+for.body:
+  %add.i7 = phi i64 [ %startval, %entry ], [ %add.i, %for.body ]
+  %i.06 = phi i32 [ 0, %entry ], [ %inc4, %for.body ]
+  %redux5 = phi i32 [ 0, %entry ], [ %inc.redux, %for.body ]
+  %add.i = add i64 %add.i7, -1
+  %kind_.i = getelementptr inbounds i32* %ptr, i64 %add.i
+  %tmp.i1 = load i32* %kind_.i, align 4
+  %inc.redux = add i32 %tmp.i1, %redux5
+  %inc4 = add i32 %i.06, 1
+  %exitcond = icmp ne i32 %inc4, 1024
+  br i1 %exitcond, label %for.body, label %loopend
+
+loopend:
+  ret i32 %inc.redux
+}
+
+; CHECK: reverse_induction_i128
+; CHECK: add <4 x i128> %[[SPLAT:.*]], <i128 0, i128 -1, i128 -2, i128 -3>
+; CHECK: add <4 x i128> %[[SPLAT]], <i128 -4, i128 -5, i128 -6, i128 -7>
+define i32 @reverse_induction_i128(i128 %startval, i32 * %ptr) {
+entry:
+  br label %for.body
+
+for.body:
+  %add.i7 = phi i128 [ %startval, %entry ], [ %add.i, %for.body ]
+  %i.06 = phi i32 [ 0, %entry ], [ %inc4, %for.body ]
+  %redux5 = phi i32 [ 0, %entry ], [ %inc.redux, %for.body ]
+  %add.i = add i128 %add.i7, -1
+  %kind_.i = getelementptr inbounds i32* %ptr, i128 %add.i
+  %tmp.i1 = load i32* %kind_.i, align 4
+  %inc.redux = add i32 %tmp.i1, %redux5
+  %inc4 = add i32 %i.06, 1
+  %exitcond = icmp ne i32 %inc4, 1024
+  br i1 %exitcond, label %for.body, label %loopend
+
+loopend:
+  ret i32 %inc.redux
+}
+
+; CHECK: reverse_induction_i16
+; CHECK: add <4 x i16> %[[SPLAT:.*]], <i16 0, i16 -1, i16 -2, i16 -3>
+; CHECK: add <4 x i16> %[[SPLAT]], <i16 -4, i16 -5, i16 -6, i16 -7>
+
+define i32 @reverse_induction_i16(i16 %startval, i32 * %ptr) {
+entry:
+  br label %for.body
+
+for.body:
+  %add.i7 = phi i16 [ %startval, %entry ], [ %add.i, %for.body ]
+  %i.06 = phi i32 [ 0, %entry ], [ %inc4, %for.body ]
+  %redux5 = phi i32 [ 0, %entry ], [ %inc.redux, %for.body ]
+  %add.i = add i16 %add.i7, -1
+  %kind_.i = getelementptr inbounds i32* %ptr, i16 %add.i
+  %tmp.i1 = load i32* %kind_.i, align 4
+  %inc.redux = add i32 %tmp.i1, %redux5
+  %inc4 = add i32 %i.06, 1
+  %exitcond = icmp ne i32 %inc4, 1024
+  br i1 %exitcond, label %for.body, label %loopend
+
+loopend:
+  ret i32 %inc.redux
+}
+
+