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https://github.com/c64scene-ar/llvm-6502.git
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d0dbe02fd2
The C and C++ semantics for compare_exchange require it to return a bool
indicating success. This gets mapped to LLVM IR which follows each cmpxchg with
an icmp of the value loaded against the desired value.
When lowered to ldxr/stxr loops, this extra comparison is redundant: its
results are implicit in the control-flow of the function.
This commit makes two changes: it replaces that icmp with appropriate PHI
nodes, and then makes sure earlyCSE is called after expansion to actually make
use of the opportunities revealed.
I've also added -{arm,aarch64}-enable-atomic-tidy options, so that
existing fragile tests aren't perturbed too much by the change. Many
of them either rely on undef/unreachable too pervasively to be
restored to something well-defined (particularly while making sure
they test the same obscure assert from many years ago), or depend on a
particular CFG shape, which is disrupted by SimplifyCFG.
rdar://problem/16227836
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209883 91177308-0d34-0410-b5e6-96231b3b80d8
102 lines
2.3 KiB
LLVM
102 lines
2.3 KiB
LLVM
; RUN: llc -mtriple=thumbv7s-apple-ios7.0 -o - %s | FileCheck %s
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define i32 @test_return(i32* %p, i32 %oldval, i32 %newval) {
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; CHECK-LABEL: test_return:
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; CHECK: dmb ishst
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; CHECK: [[LOOP:LBB[0-9]+_[0-9]+]]:
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; CHECK: ldrex [[LOADED:r[0-9]+]], [r0]
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; CHECK: cmp [[LOADED]], r1
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; CHECK: bne [[FAILED:LBB[0-9]+_[0-9]+]]
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; CHECK: strex [[STATUS:r[0-9]+]], {{r[0-9]+}}, [r0]
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; CHECK: cmp [[STATUS]], #0
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; CHECK: bne [[LOOP]]
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; CHECK-NOT: cmp {{r[0-9]+}}, {{r[0-9]+}}
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; CHECK: movs r0, #1
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; CHECK: dmb ish
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; CHECK: bx lr
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; CHECK: [[FAILED]]:
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; CHECK-NOT: cmp {{r[0-9]+}}, {{r[0-9]+}}
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; CHECK: movs r0, #0
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; CHECK: dmb ish
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; CHECK: bx lr
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%loaded = cmpxchg i32* %p, i32 %oldval, i32 %newval seq_cst seq_cst
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%success = icmp eq i32 %loaded, %oldval
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%conv = zext i1 %success to i32
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ret i32 %conv
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}
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define i1 @test_return_bool(i8* %value, i8 %oldValue, i8 %newValue) {
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; CHECK-LABEL: test_return_bool:
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; CHECK: uxtb [[OLDBYTE:r[0-9]+]], r1
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; CHECK: dmb ishst
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; CHECK: [[LOOP:LBB[0-9]+_[0-9]+]]:
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; CHECK: ldrexb [[LOADED:r[0-9]+]], [r0]
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; CHECK: cmp [[LOADED]], [[OLDBYTE]]
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; CHECK: itt ne
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; CHECK: movne r0, #1
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; CHECK: bxne lr
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; CHECK: strexb [[STATUS:r[0-9]+]], {{r[0-9]+}}, [r0]
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; CHECK: cmp [[STATUS]], #0
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; CHECK: bne [[LOOP]]
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; CHECK-NOT: cmp {{r[0-9]+}}, {{r[0-9]+}}
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; CHECK: movs r0, #0
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; CHECK: bx lr
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%loaded = cmpxchg i8* %value, i8 %oldValue, i8 %newValue acq_rel monotonic
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%failure = icmp ne i8 %loaded, %oldValue
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ret i1 %failure
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}
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define void @test_conditional(i32* %p, i32 %oldval, i32 %newval) {
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; CHECK-LABEL: test_conditional:
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; CHECK: dmb ishst
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; CHECK: [[LOOP:LBB[0-9]+_[0-9]+]]:
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; CHECK: ldrex [[LOADED:r[0-9]+]], [r0]
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; CHECK: cmp [[LOADED]], r1
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; CHECK: bne [[FAILED:LBB[0-9]+_[0-9]+]]
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; CHECK: strex [[STATUS:r[0-9]+]], r2, [r0]
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; CHECK: cmp [[STATUS]], #0
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; CHECK: bne [[LOOP]]
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; CHECK-NOT: cmp {{r[0-9]+}}, {{r[0-9]+}}
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; CHECK: dmb ish
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; CHECK: b.w _bar
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; CHECK: [[FAILED]]:
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; CHECK-NOT: cmp {{r[0-9]+}}, {{r[0-9]+}}
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; CHECK: dmb ish
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; CHECK: b.w _baz
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%loaded = cmpxchg i32* %p, i32 %oldval, i32 %newval seq_cst seq_cst
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%success = icmp eq i32 %loaded, %oldval
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br i1 %success, label %true, label %false
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true:
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tail call void @bar() #2
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br label %end
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false:
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tail call void @baz() #2
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br label %end
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end:
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ret void
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}
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declare void @bar()
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declare void @baz()
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