Robin Morisset 6c0e1e0fa6 Weak relaxing of the constraints on atomics in MemoryDependencyAnalysis
Monotonic accesses do not have to kill the analysis, as long as the QueryInstr is not
itself atomic.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215942 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-18 22:18:11 +00:00

155 lines
4.0 KiB
LLVM

; RUN: opt -basicaa -dse -S < %s | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
target triple = "x86_64-apple-macosx10.7.0"
; Sanity tests for atomic stores.
; Note that it turns out essentially every transformation DSE does is legal on
; atomic ops, just some transformations are not allowed across them.
@x = common global i32 0, align 4
@y = common global i32 0, align 4
declare void @randomop(i32*)
; DSE across unordered store (allowed)
define void @test1() nounwind uwtable ssp {
; CHECK: test1
; CHECK-NOT: store i32 0
; CHECK: store i32 1
entry:
store i32 0, i32* @x
store atomic i32 0, i32* @y unordered, align 4
store i32 1, i32* @x
ret void
}
; DSE across seq_cst load (allowed in theory; not implemented ATM)
define i32 @test2() nounwind uwtable ssp {
; CHECK: test2
; CHECK: store i32 0
; CHECK: store i32 1
entry:
store i32 0, i32* @x
%x = load atomic i32* @y seq_cst, align 4
store i32 1, i32* @x
ret i32 %x
}
; DSE across seq_cst store (store before atomic store must not be removed)
define void @test3() nounwind uwtable ssp {
; CHECK: test3
; CHECK: store i32
; CHECK: store atomic i32 2
entry:
store i32 0, i32* @x
store atomic i32 2, i32* @y seq_cst, align 4
store i32 1, i32* @x
ret void
}
; DSE remove unordered store (allowed)
define void @test4() nounwind uwtable ssp {
; CHECK: test4
; CHECK-NOT: store atomic
; CHECK: store i32 1
entry:
store atomic i32 0, i32* @x unordered, align 4
store i32 1, i32* @x
ret void
}
; DSE unordered store overwriting non-atomic store (allowed)
define void @test5() nounwind uwtable ssp {
; CHECK: test5
; CHECK: store atomic i32 1
entry:
store i32 0, i32* @x
store atomic i32 1, i32* @x unordered, align 4
ret void
}
; DSE no-op unordered atomic store (allowed)
define void @test6() nounwind uwtable ssp {
; CHECK: test6
; CHECK-NOT: store
; CHECK: ret void
entry:
%x = load atomic i32* @x unordered, align 4
store atomic i32 %x, i32* @x unordered, align 4
ret void
}
; DSE seq_cst store (be conservative; DSE doesn't have infrastructure
; to reason about atomic operations).
define void @test7() nounwind uwtable ssp {
; CHECK: test7
; CHECK: store atomic
entry:
%a = alloca i32
store atomic i32 0, i32* %a seq_cst, align 4
ret void
}
; DSE and seq_cst load (be conservative; DSE doesn't have infrastructure
; to reason about atomic operations).
define i32 @test8() nounwind uwtable ssp {
; CHECK: test8
; CHECK: store
; CHECK: load atomic
entry:
%a = alloca i32
call void @randomop(i32* %a)
store i32 0, i32* %a, align 4
%x = load atomic i32* @x seq_cst, align 4
ret i32 %x
}
; DSE across monotonic load (allowed as long as the eliminated store isUnordered)
define i32 @test9() nounwind uwtable ssp {
; CHECK: test9
; CHECK-NOT: store i32 0
; CHECK: store i32 1
entry:
store i32 0, i32* @x
%x = load atomic i32* @y monotonic, align 4
store i32 1, i32* @x
ret i32 %x
}
; DSE across monotonic store (allowed as long as the eliminated store isUnordered)
define void @test10() nounwind uwtable ssp {
; CHECK: test10
; CHECK-NOT: store i32 0
; CHECK: store i32 1
entry:
store i32 0, i32* @x
store atomic i32 42, i32* @y monotonic, align 4
store i32 1, i32* @x
ret void
}
; DSE across monotonic load (forbidden since the eliminated store is atomic)
define i32 @test11() nounwind uwtable ssp {
; CHECK: test11
; CHECK: store atomic i32 0
; CHECK: store atomic i32 1
entry:
store atomic i32 0, i32* @x monotonic, align 4
%x = load atomic i32* @y monotonic, align 4
store atomic i32 1, i32* @x monotonic, align 4
ret i32 %x
}
; DSE across monotonic store (forbidden since the eliminated store is atomic)
define void @test12() nounwind uwtable ssp {
; CHECK: test12
; CHECK: store atomic i32 0
; CHECK: store atomic i32 1
entry:
store atomic i32 0, i32* @x monotonic, align 4
store atomic i32 42, i32* @y monotonic, align 4
store atomic i32 1, i32* @x monotonic, align 4
ret void
}