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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
65 lines
1.3 KiB
LLVM
65 lines
1.3 KiB
LLVM
; RUN: llc < %s -mtriple=thumbv8 -arm-atomic-cfg-tidy=0 | FileCheck %s
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; RUN: llc < %s -mtriple=thumbv7 -arm-atomic-cfg-tidy=0 -arm-restrict-it | FileCheck %s
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; CHECK: it ne
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; CHECK-NEXT: cmpne
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; CHECK-NEXT: bne [[JUMPTARGET:.LBB[0-9]+_[0-9]+]]
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; CHECK: cmp
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; CHECK-NEXT: beq
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; CHECK-NEXT: %if.else163
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; CHECK-NEXT: mov.w
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; CHECK-NEXT: b
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; CHECK-NEXT: %if.else145
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; CHECK-NEXT: mov.w
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; CHECK: [[JUMPTARGET]]:{{.*}}%if.else173
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%struct.hc = type { i32, i32, i32, i32 }
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define i32 @t(i32 %type) optsize {
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entry:
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br i1 undef, label %if.then, label %if.else
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if.then:
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unreachable
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if.else:
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br i1 undef, label %if.then15, label %if.else18
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if.then15:
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unreachable
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if.else18:
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switch i32 %type, label %if.else173 [
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i32 3, label %if.then115
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i32 1, label %if.then102
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]
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if.then102:
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br i1 undef, label %cond.true10.i, label %t.exit
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cond.true10.i:
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br label %t.exit
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t.exit:
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unreachable
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if.then115:
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br i1 undef, label %if.else163, label %if.else145
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if.else145:
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%call150 = call fastcc %struct.hc* @foo(%struct.hc* undef, i32 34865152) optsize
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br label %while.body172
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if.else163:
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%call168 = call fastcc %struct.hc* @foo(%struct.hc* undef, i32 34078720) optsize
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br label %while.body172
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while.body172:
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br label %while.body172
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if.else173:
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ret i32 -1
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}
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declare hidden fastcc %struct.hc* @foo(%struct.hc* nocapture, i32) nounwind optsize
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