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3bb84c9bcc
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
llvm-svn: 209883
43 lines
1.1 KiB
LLVM
43 lines
1.1 KiB
LLVM
; RUN: llc < %s -mtriple=armv7-apple-darwin -arm-atomic-cfg-tidy=0 | FileCheck %s
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define double @f1() nounwind {
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; CHECK-LABEL: f1:
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; CHECK: .data_region
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; CHECK: .long 1413754129
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; CHECK: .long 1074340347
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; CHECK: .end_data_region
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ret double 0x400921FB54442D11
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}
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define i32 @f2() {
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; CHECK-LABEL: f2:
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; CHECK: .data_region jt32
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; CHECK: .end_data_region
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entry:
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switch i32 undef, label %return [
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i32 1, label %sw.bb
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i32 2, label %sw.bb6
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i32 3, label %sw.bb13
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i32 4, label %sw.bb20
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]
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sw.bb: ; preds = %entry
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br label %return
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sw.bb6: ; preds = %entry
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br label %return
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sw.bb13: ; preds = %entry
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br label %return
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sw.bb20: ; preds = %entry
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%div = sdiv i32 undef, undef
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br label %return
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return: ; preds = %sw.bb20, %sw.bb13, %sw.bb6, %sw.bb, %entry
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%retval.0 = phi i32 [ %div, %sw.bb20 ], [ undef, %sw.bb13 ], [ undef, %sw.bb6 ], [ undef, %sw.bb ], [ 0, %entry ]
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ret i32 %retval.0
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}
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