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llvm-mirror/test/Transforms/LICM/atomics.ll
Alina Sbirlea 1542bebc55 [LoopPassManager + MemorySSA] Only enable use of MemorySSA for LPMs known to preserve it. 
Summary:
Add a flag to the FunctionToLoopAdaptor that allows enabling MemorySSA only for the loop pass managers that are known to preserve it.

If an LPM is known to have only loop transforms that *all* preserve MemorySSA, then use MemorySSA if `EnableMSSALoopDependency` is set.
If an LPM has loop passes that do not preserve MemorySSA, then the flag passed is `false`, regardless of the value of `EnableMSSALoopDependency`.

When using a custom loop pass pipeline via `passes=...`, use keyword `loop` vs `loop-mssa` to use MemorySSA in that LPM. If a loop that does not preserve MemorySSA is added while using the `loop-mssa` keyword, that's an error.

Add the new `loop-mssa` keyword to a few tests where a difference occurs when enabling MemorySSA.

Reviewers: chandlerc

Subscribers: mehdi_amini, Prazek, george.burgess.iv, sanjoy.google, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66376

llvm-svn: 369548
2019-08-21 17:00:57 +00:00

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; RUN: opt < %s -S -basicaa -licm -enable-mssa-loop-dependency=false | FileCheck -check-prefixes=CHECK,AST %s
; RUN: opt < %s -S -basicaa -licm -enable-mssa-loop-dependency=true | FileCheck -check-prefixes=CHECK,MSSA %s
; RUN: opt -aa-pipeline=basic-aa -passes='require<opt-remark-emit>,loop(licm)' < %s -S | FileCheck -check-prefixes=CHECK,AST %s
; RUN: opt -aa-pipeline=basic-aa -passes='require<opt-remark-emit>,loop-mssa(licm)' < %s -S | FileCheck -check-prefixes=CHECK,MSSA %s
; Check that we can hoist unordered loads
define i32 @test1(i32* nocapture %y) nounwind uwtable ssp {
entry:
br label %loop
loop:
%i = phi i32 [ %inc, %loop ], [ 0, %entry ]
%val = load atomic i32, i32* %y unordered, align 4
%inc = add nsw i32 %i, 1
%exitcond = icmp eq i32 %inc, %val
br i1 %exitcond, label %end, label %loop
end:
ret i32 %val
; CHECK-LABEL: define i32 @test1(
; CHECK: load atomic
; CHECK-NEXT: br label %loop
}
; Check that we don't sink/hoist monotonic loads
; (Strictly speaking, it's not forbidden, but it's supposed to be possible to
; use monotonic for spinlock-like constructs.)
define i32 @test2(i32* nocapture %y) nounwind uwtable ssp {
entry:
br label %loop
loop:
%val = load atomic i32, i32* %y monotonic, align 4
%exitcond = icmp ne i32 %val, 0
br i1 %exitcond, label %end, label %loop
end:
ret i32 %val
; CHECK-LABEL: define i32 @test2(
; CHECK: load atomic
; CHECK-NEXT: %exitcond = icmp ne
; CHECK-NEXT: br i1 %exitcond, label %end, label %loop
}
; Check that we hoist unordered around monotonic.
; (The noalias shouldn't be necessary in theory, but LICM isn't quite that
; smart yet.)
define i32 @test3(i32* nocapture noalias %x, i32* nocapture %y) nounwind uwtable ssp {
entry:
br label %loop
loop:
%vala = load atomic i32, i32* %y monotonic, align 4
%valb = load atomic i32, i32* %x unordered, align 4
%exitcond = icmp ne i32 %vala, %valb
br i1 %exitcond, label %end, label %loop
end:
ret i32 %vala
; CHECK-LABEL: define i32 @test3(
; CHECK: load atomic i32, i32* %x unordered
; CHECK-NEXT: br label %loop
}
; We can sink an unordered store
define i32 @test4(i32* nocapture noalias %x, i32* nocapture %y) nounwind uwtable ssp {
entry:
br label %loop
loop:
%vala = load atomic i32, i32* %y monotonic, align 4
store atomic i32 %vala, i32* %x unordered, align 4
%exitcond = icmp ne i32 %vala, 0
br i1 %exitcond, label %end, label %loop
end:
ret i32 %vala
; CHECK-LABEL: define i32 @test4(
; CHECK-LABEL: loop:
; CHECK: load atomic i32, i32* %y monotonic
; CHECK-NOT: store
; CHECK-LABEL: end:
; CHECK-NEXT: %[[LCSSAPHI:.*]] = phi i32 [ %vala
; CHECK: store atomic i32 %[[LCSSAPHI]], i32* %x unordered, align 4
}
; We currently don't handle ordered atomics.
define i32 @test5(i32* nocapture noalias %x, i32* nocapture %y) nounwind uwtable ssp {
entry:
br label %loop
loop:
%vala = load atomic i32, i32* %y monotonic, align 4
store atomic i32 %vala, i32* %x release, align 4
%exitcond = icmp ne i32 %vala, 0
br i1 %exitcond, label %end, label %loop
end:
ret i32 %vala
; CHECK-LABEL: define i32 @test5(
; CHECK: load atomic i32, i32* %y monotonic
; CHECK-NEXT: store atomic
}
; We currently don't touch volatiles
define i32 @test6(i32* nocapture noalias %x, i32* nocapture %y) nounwind uwtable ssp {
entry:
br label %loop
loop:
%vala = load atomic i32, i32* %y monotonic, align 4
store volatile i32 %vala, i32* %x, align 4
%exitcond = icmp ne i32 %vala, 0
br i1 %exitcond, label %end, label %loop
end:
ret i32 %vala
; CHECK-LABEL: define i32 @test6(
; CHECK: load atomic i32, i32* %y monotonic
; CHECK-NEXT: store volatile
}
; We currently don't touch volatiles
define i32 @test6b(i32* nocapture noalias %x, i32* nocapture %y) nounwind uwtable ssp {
entry:
br label %loop
loop:
%vala = load atomic i32, i32* %y monotonic, align 4
store atomic volatile i32 %vala, i32* %x unordered, align 4
%exitcond = icmp ne i32 %vala, 0
br i1 %exitcond, label %end, label %loop
end:
ret i32 %vala
; CHECK-LABEL: define i32 @test6b(
; CHECK: load atomic i32, i32* %y monotonic
; CHECK-NEXT: store atomic volatile
}
; Mixing unorder atomics and normal loads/stores is
; current unimplemented
define i32 @test7(i32* nocapture noalias %x, i32* nocapture %y) nounwind uwtable ssp {
entry:
br label %loop
loop:
store i32 5, i32* %x
%vala = load atomic i32, i32* %y monotonic, align 4
store atomic i32 %vala, i32* %x unordered, align 4
%exitcond = icmp ne i32 %vala, 0
br i1 %exitcond, label %end, label %loop
end:
ret i32 %vala
; CHECK-LABEL: define i32 @test7(
; CHECK: store i32 5, i32* %x
; CHECK-NEXT: load atomic i32, i32* %y
; CHECK-NEXT: store atomic i32
}
; Three provably noalias locations - we can sink normal and unordered, but
; not monotonic
define i32 @test7b(i32* nocapture noalias %x, i32* nocapture %y, i32* noalias nocapture %z) nounwind uwtable ssp {
entry:
br label %loop
loop:
store i32 5, i32* %x
%vala = load atomic i32, i32* %y monotonic, align 4
store atomic i32 %vala, i32* %z unordered, align 4
%exitcond = icmp ne i32 %vala, 0
br i1 %exitcond, label %end, label %loop
end:
ret i32 %vala
; CHECK-LABEL: define i32 @test7b(
; AST-LABEL: entry:
; AST: store i32 5, i32* %x
; CHECK-LABEL: loop:
; CHECK: load atomic i32, i32* %y monotonic
; CHECK-LABEL: end:
; MSSA: store i32 5, i32* %x
; CHECK: store atomic i32 %{{.+}}, i32* %z unordered, align 4
}
define i32 @test8(i32* nocapture noalias %x, i32* nocapture %y) {
entry:
br label %loop
loop:
%vala = load atomic i32, i32* %y monotonic, align 4
store atomic i32 %vala, i32* %x unordered, align 4
fence release
%exitcond = icmp ne i32 %vala, 0
br i1 %exitcond, label %end, label %loop
end:
ret i32 %vala
; CHECK-LABEL: define i32 @test8(
; CHECK-LABEL: loop:
; CHECK: load atomic i32, i32* %y monotonic
; CHECK-NEXT: store atomic
; CHECK-NEXT: fence
}
; Exact semantics of monotonic accesses are a bit vague in the C++ spec,
; for the moment, be conservative and don't touch them.
define i32 @test9(i32* nocapture noalias %x, i32* nocapture %y) {
entry:
br label %loop
loop:
%vala = load atomic i32, i32* %y monotonic, align 4
store atomic i32 %vala, i32* %x monotonic, align 4
%exitcond = icmp ne i32 %vala, 0
br i1 %exitcond, label %end, label %loop
end:
ret i32 %vala
; CHECK-LABEL: define i32 @test9(
; CHECK-LABEL: loop:
; CHECK: load atomic i32, i32* %y monotonic
; CHECK-NEXT: store atomic i32 %vala, i32* %x monotonic, align 4
}
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