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| author | Tim Northover <tnorthover@apple.com> | 2014-05-30 10:09:59 +0000 |
|---|---|---|
| committer | Tim Northover <tnorthover@apple.com> | 2014-05-30 10:09:59 +0000 |
| commit | b4ddc0845ab5260023e9afa3f7bc71a0bc731ae6 (patch) | |
| tree | 37a8539f9db4739dd57e7bdf39433594e822e2ec /llvm/test/CodeGen/AArch64/breg.ll | |
| parent | 5070c18928e4b4855202ee327f537c7a1969051e (diff) | |
| download | bcm5719-llvm-b4ddc0845ab5260023e9afa3f7bc71a0bc731ae6.tar.gz bcm5719-llvm-b4ddc0845ab5260023e9afa3f7bc71a0bc731ae6.zip | |
ARM & AArch64: make use of common cmpxchg idioms after expansion
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
Diffstat (limited to 'llvm/test/CodeGen/AArch64/breg.ll')
| -rw-r--r-- | llvm/test/CodeGen/AArch64/breg.ll | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/llvm/test/CodeGen/AArch64/breg.ll b/llvm/test/CodeGen/AArch64/breg.ll index 591f48303e2..952404495ce 100644 --- a/llvm/test/CodeGen/AArch64/breg.ll +++ b/llvm/test/CodeGen/AArch64/breg.ll @@ -1,4 +1,4 @@ -; RUN: llc -verify-machineinstrs -o - %s -mtriple=aarch64-linux-gnu | FileCheck %s +; RUN: llc -verify-machineinstrs -o - %s -mtriple=aarch64-linux-gnu -aarch64-atomic-cfg-tidy=0 | FileCheck %s @stored_label = global i8* null |
