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llvm-mirror/test/Transforms/LoopDeletion/noop-loops-with-subloops.ll

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[LoopDeletion] Add test case where outer loop needs to be deleted. In the test case @test1, the inner loop cannot be removed, because it has a live-out value. But the outer loop is a no-op and can be removed.
2020-12-22 18:48:01 +01:00
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -loop-deletion -verify-dom-info -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"
%pair_t = type { i64, i64 }
; The loop %inner cannot be removed, because it has outgoing values. But the
; outer loop is a no-op and can be removed.
define void @test1(i64 %N, i64 %M, %pair_t* %ptr) willreturn {
; CHECK-LABEL: @test1(
; CHECK-NEXT: entry:
[LoopDeletion] Also consider loops with subloops for deletion. Currently, LoopDeletion does skip loops that have sub-loops, but this means we currently fail to remove some no-op loops. One example are inner loops with live-out values. Those cannot be removed by itself. But the containing loop may itself be a no-op and the whole loop-nest can be deleted. The legality checks do not seem to rely on analyzing inner-loops only for correctness. With LoopDeletion being a LoopPass, the change means that we now unfortunately need to do some extra work in parent loops, by checking some conditions we already checked. But there appears to be no noticeable compile time impact: http://llvm-compile-time-tracker.com/compare.php?from=02d11f3cda2ab5b8bf4fc02639fd1f4b8c45963e&to=843201e9cf3b6871e18c52aede5897a22994c36c&stat=instructions This changes patch leads to ~10 more loops being deleted on MultiSource, SPEC2000, SPEC2006 with -O3 & LTO This patch is also required (together with a few others) to eliminate a no-op loop in omnetpp as discussed on llvm-dev 'LoopDeletion / removal of empty loops.' (http://lists.llvm.org/pipermail/llvm-dev/2020-December/147462.html) This change becomes relevant after removing potentially infinite loops is made possible in 'must-progress' loops (D86844). Note that I added a function call with side-effects to an outer loop in `llvm/test/Transforms/LoopDeletion/update-scev.ll` to preserve the original spirit of the test. Reviewed By: reames Differential Revision: https://reviews.llvm.org/D93716
2021-01-06 12:51:52 +01:00
; CHECK-NEXT: br label [[EXIT:%.*]]
[LoopDeletion] Add test case where outer loop needs to be deleted. In the test case @test1, the inner loop cannot be removed, because it has a live-out value. But the outer loop is a no-op and can be removed.
2020-12-22 18:48:01 +01:00
; CHECK: exit:
; CHECK-NEXT: ret void
;
entry:
br label %outer.header
outer.header:
%outer.iv = phi i64 [ 0, %entry ], [ %outer.iv.next, %outer.latch ]
br label %inner
inner:
%inner.iv = phi i64 [ 0, %outer.header ], [ %inner.iv.next, %inner ]
%gep = getelementptr %pair_t, %pair_t* %ptr, i64 %inner.iv
%p = load %pair_t, %pair_t* %gep
%v.0 = extractvalue %pair_t %p, 0
%v.1 = extractvalue %pair_t %p, 1
%inner.ec = icmp ult i64 %v.0, %v.1
%inner.iv.next = add i64 %inner.iv, 1
br i1 %inner.ec, label %outer.latch, label %inner
outer.latch:
%lcssa = phi i64 [ %v.1, %inner ]
%outer.ec = icmp ult i64 %outer.iv, %lcssa
%outer.iv.next = add i64 %outer.iv, 1
br i1 %outer.ec, label %exit, label %outer.header
exit:
ret void
}
declare void @sideeffect()
; Same as @test1, but with a call in the outer loop. Nothing can be deleted.
define void @test2_sideeffect_in_outer(i64 %N, i64 %M, %pair_t* %ptr) willreturn {
; CHECK-LABEL: @test2_sideeffect_in_outer(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[OUTER_HEADER:%.*]]
; CHECK: outer.header:
Revert "[LoopDeletion] Break backedge if we can prove that the loop is exited on 1st iteration" This reverts commit 2531fd70d19aa5d61feb533bbdeee7717a4129eb due to performance regression on the PPC buildbot.
2021-05-25 22:58:13 +02:00
; CHECK-NEXT: [[OUTER_IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[OUTER_IV_NEXT:%.*]], [[OUTER_LATCH:%.*]] ]
[LoopDeletion] Add test case where outer loop needs to be deleted. In the test case @test1, the inner loop cannot be removed, because it has a live-out value. But the outer loop is a no-op and can be removed.
2020-12-22 18:48:01 +01:00
; CHECK-NEXT: br label [[INNER:%.*]]
; CHECK: inner:
; CHECK-NEXT: [[INNER_IV:%.*]] = phi i64 [ 0, [[OUTER_HEADER]] ], [ [[INNER_IV_NEXT:%.*]], [[INNER]] ]
; CHECK-NEXT: [[GEP:%.*]] = getelementptr [[PAIR_T:%.*]], %pair_t* [[PTR:%.*]], i64 [[INNER_IV]]
; CHECK-NEXT: [[P:%.*]] = load [[PAIR_T]], %pair_t* [[GEP]], align 4
; CHECK-NEXT: [[V_0:%.*]] = extractvalue [[PAIR_T]] [[P]], 0
; CHECK-NEXT: [[V_1:%.*]] = extractvalue [[PAIR_T]] [[P]], 1
; CHECK-NEXT: [[INNER_EC:%.*]] = icmp ult i64 [[V_0]], [[V_1]]
; CHECK-NEXT: [[INNER_IV_NEXT]] = add i64 [[INNER_IV]], 1
Revert "[LoopDeletion] Break backedge if we can prove that the loop is exited on 1st iteration" This reverts commit 2531fd70d19aa5d61feb533bbdeee7717a4129eb due to performance regression on the PPC buildbot.
2021-05-25 22:58:13 +02:00
; CHECK-NEXT: br i1 [[INNER_EC]], label [[OUTER_LATCH]], label [[INNER]]
[LoopDeletion] Add test case where outer loop needs to be deleted. In the test case @test1, the inner loop cannot be removed, because it has a live-out value. But the outer loop is a no-op and can be removed.
2020-12-22 18:48:01 +01:00
; CHECK: outer.latch:
; CHECK-NEXT: [[LCSSA:%.*]] = phi i64 [ [[V_1]], [[INNER]] ]
; CHECK-NEXT: [[OUTER_EC:%.*]] = icmp ult i64 [[OUTER_IV]], [[LCSSA]]
Revert "[LoopDeletion] Break backedge if we can prove that the loop is exited on 1st iteration" This reverts commit 2531fd70d19aa5d61feb533bbdeee7717a4129eb due to performance regression on the PPC buildbot.
2021-05-25 22:58:13 +02:00
; CHECK-NEXT: [[OUTER_IV_NEXT]] = add i64 [[OUTER_IV]], 1
[LoopDeletion] Add test case where outer loop needs to be deleted. In the test case @test1, the inner loop cannot be removed, because it has a live-out value. But the outer loop is a no-op and can be removed.
2020-12-22 18:48:01 +01:00
; CHECK-NEXT: call void @sideeffect()
Revert "[LoopDeletion] Break backedge if we can prove that the loop is exited on 1st iteration" This reverts commit 2531fd70d19aa5d61feb533bbdeee7717a4129eb due to performance regression on the PPC buildbot.
2021-05-25 22:58:13 +02:00
; CHECK-NEXT: br i1 [[OUTER_EC]], label [[EXIT:%.*]], label [[OUTER_HEADER]]
[LoopDeletion] Add test case where outer loop needs to be deleted. In the test case @test1, the inner loop cannot be removed, because it has a live-out value. But the outer loop is a no-op and can be removed.
2020-12-22 18:48:01 +01:00
; CHECK: exit:
; CHECK-NEXT: ret void
;
entry:
br label %outer.header
outer.header:
%outer.iv = phi i64 [ 0, %entry ], [ %outer.iv.next, %outer.latch ]
br label %inner
inner:
%inner.iv = phi i64 [ 0, %outer.header ], [ %inner.iv.next, %inner ]
%gep = getelementptr %pair_t, %pair_t* %ptr, i64 %inner.iv
%p = load %pair_t, %pair_t* %gep
%v.0 = extractvalue %pair_t %p, 0
%v.1 = extractvalue %pair_t %p, 1
%inner.ec = icmp ult i64 %v.0, %v.1
%inner.iv.next = add i64 %inner.iv, 1
br i1 %inner.ec, label %outer.latch, label %inner
outer.latch:
%lcssa = phi i64 [ %v.1, %inner ]
%outer.ec = icmp ult i64 %outer.iv, %lcssa
%outer.iv.next = add i64 %outer.iv, 1
call void @sideeffect()
br i1 %outer.ec, label %exit, label %outer.header
exit:
ret void
}
; Same as @test1, but with a call in the inner loop. Nothing can be deleted.
define void @test3_sideeffect_in_inner(i64 %N, i64 %M, %pair_t* %ptr) willreturn {
; CHECK-LABEL: @test3_sideeffect_in_inner(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[OUTER_HEADER:%.*]]
; CHECK: outer.header:
Revert "[LoopDeletion] Break backedge if we can prove that the loop is exited on 1st iteration" This reverts commit 2531fd70d19aa5d61feb533bbdeee7717a4129eb due to performance regression on the PPC buildbot.
2021-05-25 22:58:13 +02:00
; CHECK-NEXT: [[OUTER_IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[OUTER_IV_NEXT:%.*]], [[OUTER_LATCH:%.*]] ]
[LoopDeletion] Add test case where outer loop needs to be deleted. In the test case @test1, the inner loop cannot be removed, because it has a live-out value. But the outer loop is a no-op and can be removed.
2020-12-22 18:48:01 +01:00
; CHECK-NEXT: br label [[INNER:%.*]]
; CHECK: inner:
; CHECK-NEXT: [[INNER_IV:%.*]] = phi i64 [ 0, [[OUTER_HEADER]] ], [ [[INNER_IV_NEXT:%.*]], [[INNER]] ]
; CHECK-NEXT: [[GEP:%.*]] = getelementptr [[PAIR_T:%.*]], %pair_t* [[PTR:%.*]], i64 [[INNER_IV]]
; CHECK-NEXT: [[P:%.*]] = load [[PAIR_T]], %pair_t* [[GEP]], align 4
; CHECK-NEXT: [[V_0:%.*]] = extractvalue [[PAIR_T]] [[P]], 0
; CHECK-NEXT: [[V_1:%.*]] = extractvalue [[PAIR_T]] [[P]], 1
; CHECK-NEXT: [[INNER_EC:%.*]] = icmp ult i64 [[V_0]], [[V_1]]
; CHECK-NEXT: [[INNER_IV_NEXT]] = add i64 [[INNER_IV]], 1
; CHECK-NEXT: call void @sideeffect()
Revert "[LoopDeletion] Break backedge if we can prove that the loop is exited on 1st iteration" This reverts commit 2531fd70d19aa5d61feb533bbdeee7717a4129eb due to performance regression on the PPC buildbot.
2021-05-25 22:58:13 +02:00
; CHECK-NEXT: br i1 [[INNER_EC]], label [[OUTER_LATCH]], label [[INNER]]
[LoopDeletion] Add test case where outer loop needs to be deleted. In the test case @test1, the inner loop cannot be removed, because it has a live-out value. But the outer loop is a no-op and can be removed.
2020-12-22 18:48:01 +01:00
; CHECK: outer.latch:
; CHECK-NEXT: [[LCSSA:%.*]] = phi i64 [ [[V_1]], [[INNER]] ]
; CHECK-NEXT: [[OUTER_EC:%.*]] = icmp ult i64 [[OUTER_IV]], [[LCSSA]]
Revert "[LoopDeletion] Break backedge if we can prove that the loop is exited on 1st iteration" This reverts commit 2531fd70d19aa5d61feb533bbdeee7717a4129eb due to performance regression on the PPC buildbot.
2021-05-25 22:58:13 +02:00
; CHECK-NEXT: [[OUTER_IV_NEXT]] = add i64 [[OUTER_IV]], 1
; CHECK-NEXT: br i1 [[OUTER_EC]], label [[EXIT:%.*]], label [[OUTER_HEADER]]
[LoopDeletion] Add test case where outer loop needs to be deleted. In the test case @test1, the inner loop cannot be removed, because it has a live-out value. But the outer loop is a no-op and can be removed.
2020-12-22 18:48:01 +01:00
; CHECK: exit:
; CHECK-NEXT: ret void
;
entry:
br label %outer.header
outer.header:
%outer.iv = phi i64 [ 0, %entry ], [ %outer.iv.next, %outer.latch ]
br label %inner
inner:
%inner.iv = phi i64 [ 0, %outer.header ], [ %inner.iv.next, %inner ]
%gep = getelementptr %pair_t, %pair_t* %ptr, i64 %inner.iv
%p = load %pair_t, %pair_t* %gep
%v.0 = extractvalue %pair_t %p, 0
%v.1 = extractvalue %pair_t %p, 1
%inner.ec = icmp ult i64 %v.0, %v.1
%inner.iv.next = add i64 %inner.iv, 1
call void @sideeffect()
br i1 %inner.ec, label %outer.latch, label %inner
outer.latch:
%lcssa = phi i64 [ %v.1, %inner ]
%outer.ec = icmp ult i64 %outer.iv, %lcssa
%outer.iv.next = add i64 %outer.iv, 1
br i1 %outer.ec, label %exit, label %outer.header
exit:
ret void
}
[LoopDeletion] Add test with potentially infinite sub-loop. Tests for PR50511.
2021-05-28 17:58:59 +02:00
; The inner loop may not terminate, so we cannot remote it, unless the
; function/loop is mustprogress. Test case from PR50511.
define void @inner_loop_may_be_infinite(i1 %c1, i1 %c2) {
; CHECK-LABEL: @inner_loop_may_be_infinite(
; CHECK-NEXT: br label [[EXIT:%.*]]
; CHECK: exit:
; CHECK-NEXT: ret void
;
br label %loop1
loop1:
br i1 %c1, label %loop1.latch, label %loop2
loop2:
br i1 %c2, label %loop1.latch, label %loop2
loop1.latch:
br i1 false, label %loop1, label %exit
exit:
ret void
}
; Similar to @inner_loop_may_be_infinite, but with mustprogress. We can delete
; both loops.
define void @inner_loop_may_be_infinite_mustprogress(i1 %c1, i1 %c2) mustprogress {
; CHECK-LABEL: @inner_loop_may_be_infinite_mustprogress(
; CHECK-NEXT: br label [[EXIT:%.*]]
; CHECK: exit:
; CHECK-NEXT: ret void
;
br label %loop1
loop1:
br i1 %c1, label %loop1.latch, label %loop2
loop2:
br i1 %c2, label %loop1.latch, label %loop2
loop1.latch:
br i1 false, label %loop1, label %exit
exit:
ret void
}
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