From 19ea37059aaea8104ea6017abc9f1bbed610b7f2 Mon Sep 17 00:00:00 2001 From: Benjamin Kramer Date: Mon, 28 Oct 2013 07:30:06 +0000 Subject: SCEV: Make the final add of an inbounds GEP nuw if we know that the index is positive. We can't do this for the general case as saying a GEP with a negative index doesn't have unsigned wrap isn't valid for negative indices. %gep = getelementptr inbounds i32* %p, i64 -1 But an inbounds GEP cannot run past the end of address space. So we check for the very common case of a positive index and make GEPs derived from that NUW. Together with Andy's recent non-unit stride work this lets us analyze loops like void foo3(int *a, int *b) { for (; a < b; a++) {} } PR12375, PR12376. Differential Revision: http://llvm-reviews.chandlerc.com/D2033 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193514 91177308-0d34-0410-b5e6-96231b3b80d8 --- test/Analysis/ScalarEvolution/nsw.ll | 40 ++++++++++++++++++++++++++++++++++-- 1 file changed, 38 insertions(+), 2 deletions(-) (limited to 'test/Analysis') diff --git a/test/Analysis/ScalarEvolution/nsw.ll b/test/Analysis/ScalarEvolution/nsw.ll index 659cf4f..05992ea 100644 --- a/test/Analysis/ScalarEvolution/nsw.ll +++ b/test/Analysis/ScalarEvolution/nsw.ll @@ -62,11 +62,11 @@ for.body.lr.ph.i.i: ; preds = %entry for.body.i.i: ; preds = %for.body.i.i, %for.body.lr.ph.i.i %__first.addr.02.i.i = phi i32* [ %begin, %for.body.lr.ph.i.i ], [ %ptrincdec.i.i, %for.body.i.i ] ; CHECK: %__first.addr.02.i.i -; CHECK-NEXT: --> {%begin,+,4}<%for.body.i.i> +; CHECK-NEXT: --> {%begin,+,4}<%for.body.i.i> store i32 0, i32* %__first.addr.02.i.i, align 4 %ptrincdec.i.i = getelementptr inbounds i32* %__first.addr.02.i.i, i64 1 ; CHECK: %ptrincdec.i.i -; CHECK-NEXT: --> {(4 + %begin),+,4}<%for.body.i.i> +; CHECK-NEXT: --> {(4 + %begin),+,4}<%for.body.i.i> %cmp.i.i = icmp eq i32* %ptrincdec.i.i, %end br i1 %cmp.i.i, label %for.cond.for.end_crit_edge.i.i, label %for.body.i.i @@ -122,3 +122,39 @@ exit: %result = phi i32 [ %a, %entry ], [ %tmp2, %greater ] ret i32 %result } + +; TODO: This could fold down to '1' +; CHECK-LABEL: PR12375 +; CHECK: --> {(4 + %arg),+,4}<%bb1> Exits: (4 + (4 * ((-1 + (-1 * %arg) + ((4 + %arg) umax (8 + %arg))) /u 4)) + %arg) +define i32 @PR12375(i32* readnone %arg) { +bb: + %tmp = getelementptr inbounds i32* %arg, i64 2 + br label %bb1 + +bb1: ; preds = %bb1, %bb + %tmp2 = phi i32* [ %arg, %bb ], [ %tmp5, %bb1 ] + %tmp3 = phi i32 [ 0, %bb ], [ %tmp4, %bb1 ] + %tmp4 = add nsw i32 %tmp3, 1 + %tmp5 = getelementptr inbounds i32* %tmp2, i64 1 + %tmp6 = icmp ult i32* %tmp5, %tmp + br i1 %tmp6, label %bb1, label %bb7 + +bb7: ; preds = %bb1 + ret i32 %tmp4 +} + +; CHECK-LABEL: PR12376 +; CHECK: --> {(4 + %arg),+,4}<%bb2> Exits: (4 + (4 * ((3 + (-1 * %arg) + (%arg umax %arg1)) /u 4)) + %arg) +define void @PR12376(i32* nocapture %arg, i32* nocapture %arg1) { +bb: + br label %bb2 + +bb2: ; preds = %bb2, %bb + %tmp = phi i32* [ %arg, %bb ], [ %tmp4, %bb2 ] + %tmp3 = icmp ult i32* %tmp, %arg1 + %tmp4 = getelementptr inbounds i32* %tmp, i64 1 + br i1 %tmp3, label %bb2, label %bb5 + +bb5: ; preds = %bb2 + ret void +} -- cgit v1.1