From c121f5dc267e5d7048b8f27ddcfdc41f8c8e7073 Mon Sep 17 00:00:00 2001 From: Arnold Schwaighofer Date: Thu, 9 May 2013 00:32:18 +0000 Subject: LoopVectorizer: Don't assert on the absence of induction variables A computable loop exit count does not imply the presence of an induction variable. Scalar evolution can return a value for an infinite loop. Fixes PR15926. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181495 91177308-0d34-0410-b5e6-96231b3b80d8 --- test/Transforms/LoopVectorize/infiniteloop.ll | 34 +++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) create mode 100644 test/Transforms/LoopVectorize/infiniteloop.ll (limited to 'test/Transforms') diff --git a/test/Transforms/LoopVectorize/infiniteloop.ll b/test/Transforms/LoopVectorize/infiniteloop.ll new file mode 100644 index 0000000..f6ab564 --- /dev/null +++ b/test/Transforms/LoopVectorize/infiniteloop.ll @@ -0,0 +1,34 @@ +; RUN: opt -S -indvars -loop-vectorize -force-vector-width=2 < %s | FileCheck %s + +target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32-S128" + +@a = common global i64 0, align 8 +@x = common global i32 0, align 4 + +; We used to assert on this loop because we could not find an induction +; variable but assumed there must be one. Scalar evolution returned a exit +; count for the loop below and from there on we assumed that there must be an +; induction variable. This is not a valid assumption: +; // getExitCount - Get the expression for the number of loop iterations for +; // which this loop is *guaranteed not to exit* via ExitingBlock. Otherwise +; // return SCEVCouldNotCompute. +; For an infinite loop SE can return any number. + +; CHECK: fn1 +define void @fn1() { +entry: + store i64 0, i64* @a, align 8 + br label %for.body + +for.body: ; preds = %for.body, %entry + %inc1 = phi i64 [ 0, %entry ], [ %inc, %for.body ] + store volatile i32 0, i32* @x, align 4 + %inc = add nsw i64 %inc1, 1 + %cmp = icmp sgt i64 %inc1, -2 + br i1 %cmp, label %for.body, label %for.end + +for.end: ; preds = %for.body + %inc.lcssa = phi i64 [ %inc, %for.body ] + store i64 %inc.lcssa, i64* @a, align 8 + ret void +} -- cgit v1.1