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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
32 lines
611 B
LLVM
32 lines
611 B
LLVM
; RUN: llc < %s -mtriple=armv6-apple-darwin -mcpu=arm1136jf-s -arm-atomic-cfg-tidy=0 | FileCheck %s
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; Radar 8589805: Counting the number of microcoded operations, such as for an
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; LDM instruction, was causing an assertion failure because the microop count
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; was being treated as an instruction count.
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; CHECK: push
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; CHECK: pop
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; CHECK: pop
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; CHECK: pop
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define i32 @test(i32 %x) {
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entry:
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%0 = tail call signext i16 undef(i32* undef)
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switch i32 %x, label %bb3 [
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i32 0, label %bb4
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i32 1, label %bb1
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i32 2, label %bb2
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]
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bb1:
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ret i32 1
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bb2:
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ret i32 2
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bb3:
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ret i32 1
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bb4:
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ret i32 3
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}
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