mirror of
https://github.com/RPCSX/llvm.git
synced 2024-12-04 01:43:06 +00:00
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
19 lines
529 B
LLVM
19 lines
529 B
LLVM
; RUN: llc < %s -mtriple=thumbv7-apple-darwin -mcpu=cortex-a8 -arm-atomic-cfg-tidy=0 -O3 | FileCheck %s
|
|
; rdar://7493908
|
|
|
|
; Make sure the result of the first dynamic_alloc isn't copied back to sp more
|
|
; than once. We'll deal with poor codegen later.
|
|
|
|
define void @t() nounwind ssp {
|
|
entry:
|
|
; CHECK-LABEL: t:
|
|
%size = mul i32 8, 2
|
|
; CHECK: sub.w r0, sp, #16
|
|
; CHECK: mov sp, r0
|
|
%vla_a = alloca i8, i32 %size, align 8
|
|
; CHECK: sub.w r0, sp, #16
|
|
; CHECK: mov sp, r0
|
|
%vla_b = alloca i8, i32 %size, align 8
|
|
unreachable
|
|
}
|