From 1ee3c0008be6f7012aa69f7a73a2819300bdf23f Mon Sep 17 00:00:00 2001 From: Arnold Schwaighofer Date: Mon, 7 Oct 2013 21:05:43 +0000 Subject: LoopVectorize: External uses must use the last value in a reduction cycle Otherwise, we don't perform operations that would have been performed on the scalar version. Fixes PR17498. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192133 91177308-0d34-0410-b5e6-96231b3b80d8 --- test/Transforms/LoopVectorize/reduction.ll | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) (limited to 'test/Transforms/LoopVectorize') diff --git a/test/Transforms/LoopVectorize/reduction.ll b/test/Transforms/LoopVectorize/reduction.ll index 18a0a9341e..791fce1562 100644 --- a/test/Transforms/LoopVectorize/reduction.ll +++ b/test/Transforms/LoopVectorize/reduction.ll @@ -467,3 +467,30 @@ for.body: for.end: ret i32 %p.addr.02 } + +; Don't vectorize a reduction value that is not the last in a reduction cyle. We +; would loose iterations (VF-1) on the operations after that use. +; PR17498 + +; CHECK-LABEL: not_last_operation +; CHECK-NOT: x i32> +define i32 @not_last_operation(i32 %p, i32 %val) { +entry: + %tobool = icmp eq i32 %p, 0 + br label %for.body + +for.body: + %inc613.1 = phi i32 [ 0, %entry ], [ %inc6.1, %for.body ] + %inc511.1 = phi i32 [ %val, %entry ], [ %inc5.1, %for.body ] + %0 = zext i1 %tobool to i32 + %inc4.1 = xor i32 %0, 1 + %inc511.1.inc4.1 = add nsw i32 %inc511.1, %inc4.1 + %inc5.1 = add nsw i32 %inc511.1.inc4.1, 1 + %inc6.1 = add nsw i32 %inc613.1, 1 + %exitcond.1 = icmp eq i32 %inc6.1, 22 + br i1 %exitcond.1, label %exit, label %for.body + +exit: + %inc.2 = add nsw i32 %inc511.1.inc4.1, 2 + ret i32 %inc.2 +} -- cgit v1.2.3