mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-12-26 05:32:25 +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
18 lines
448 B
LLVM
18 lines
448 B
LLVM
; RUN: llc -verify-machineinstrs -o - %s -mtriple=aarch64-linux-gnu -aarch64-atomic-cfg-tidy=0 | FileCheck %s
|
|
|
|
@stored_label = global i8* null
|
|
|
|
define void @foo() {
|
|
; CHECK-LABEL: foo:
|
|
%lab = load i8** @stored_label
|
|
indirectbr i8* %lab, [label %otherlab, label %retlab]
|
|
; CHECK: adrp {{x[0-9]+}}, stored_label
|
|
; CHECK: ldr {{x[0-9]+}}, [{{x[0-9]+}}, {{#?}}:lo12:stored_label]
|
|
; CHECK: br {{x[0-9]+}}
|
|
|
|
otherlab:
|
|
ret void
|
|
retlab:
|
|
ret void
|
|
}
|