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[PM/LoopUnswitch] Remove another over-aggressive assert.

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This code path can very clearly be called in a context where we have
baselined all the cloned blocks to a particular loop and are trying to
handle nested subloops. There is no harm in this, so just relax the
assert. I've added a test case that will make sure we actually exercise
this code path.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@330680 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chandler Carruth 2018-04-24 03:27:00 +00:00
parent 903870a8da
commit eceadea770
2 changed files with 74 additions and 4 deletions
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5
lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
View File

@ -913,11 +913,8 @@ static Loop *cloneLoopNest(Loop &OrigRootL, Loop *RootParentL,
for (auto *BB : OrigL.blocks()) {
auto *ClonedBB = cast<BasicBlock>(VMap.lookup(BB));
ClonedL.addBlockEntry(ClonedBB);
if (LI.getLoopFor(BB) == &OrigL) {
assert(!LI.getLoopFor(ClonedBB) &&
"Should not have an existing loop for this block!");
if (LI.getLoopFor(BB) == &OrigL)
LI.changeLoopFor(ClonedBB, &ClonedL);
}
}
};

73
test/Transforms/SimpleLoopUnswitch/nontrivial-unswitch.ll
View File

@ -2435,3 +2435,76 @@ bb23:
%tmp1.3 = phi i32 [ %tmp1.2.lcssa, %bb19 ], [ %tmp1.1, %bb7 ]
br label %bb3
}
; A test reduced out of 400.perlbench that when unswitching the `%stop`
; condition clones a loop nest outside of a containing loop. This excercises a
; different cloning path from our other test cases and in turn verifying the
; resulting structure can catch any failures to correctly clone these nested
; loops.
declare void @f()
declare void @g()
declare i32 @h(i32 %arg)
define void @test22(i32 %arg) {
; CHECK-LABEL: define void @test22(
entry:
br label %loop1.header
loop1.header:
%stop = phi i1 [ true, %loop1.latch ], [ false, %entry ]
%i = phi i32 [ %i.lcssa, %loop1.latch ], [ %arg, %entry ]
; CHECK: %[[I:.*]] = phi i32 [ %{{.*}}, %loop1.latch ], [ %arg, %entry ]
br i1 %stop, label %loop1.exit, label %loop1.body.loop2.ph
; CHECK: br i1 %stop, label %loop1.exit, label %loop1.body.loop2.ph
loop1.body.loop2.ph:
br label %loop2.header
; Just check that the we unswitched the key condition and that leads to the
; inner loop header.
;
; CHECK: loop1.body.loop2.ph:
; CHECK-NEXT: br i1 %stop, label %[[SPLIT_US:.*]], label %[[SPLIT:.*]]
;
; CHECK: [[SPLIT_US]]:
; CHECK-NEXT: br label %[[LOOP2_HEADER_US:.*]]
;
; CHECK: [[LOOP2_HEADER_US]]:
; CHECK-NEXT: %{{.*}} = phi i32 [ %[[I]], %[[SPLIT_US]] ]
;
; CHECK: [[SPLIT]]:
; CHECK-NEXT: br label %[[LOOP2_HEADER:.*]]
;
; CHECK: [[LOOP2_HEADER]]:
; CHECK-NEXT: %{{.*}} = phi i32 [ %[[I]], %[[SPLIT]] ]
loop2.header:
%i.inner = phi i32 [ %i, %loop1.body.loop2.ph ], [ %i.next, %loop2.latch ]
br label %loop3.header
loop3.header:
%sw = call i32 @h(i32 %i.inner)
switch i32 %sw, label %loop3.exit [
i32 32, label %loop3.header
i32 59, label %loop2.latch
i32 36, label %loop1.latch
]
loop2.latch:
%i.next = add i32 %i.inner, 1
br i1 %stop, label %loop2.exit, label %loop2.header
loop1.latch:
%i.lcssa = phi i32 [ %i.inner, %loop3.header ]
br label %loop1.header
loop3.exit:
call void @f()
ret void
loop2.exit:
call void @g()
ret void
loop1.exit:
call void @g()
ret void
}