llvm-6502/test/CodeGen/ARM/ifcvt10.ll
Tim Northover d0dbe02fd2 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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209883 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-30 10:09:59 +00:00

44 lines
1.4 KiB
LLVM

; RUN: llc < %s -mtriple=arm-apple-ios -arm-atomic-cfg-tidy=0 -mcpu=cortex-a9 | FileCheck %s
; rdar://8402126
; Make sure if-converter is not predicating vldmia and ldmia. These are
; micro-coded and would have long issue latency even if predicated on
; false predicate.
define void @t(double %a, double %b, double %c, double %d, i32* nocapture %solutions, double* nocapture %x) nounwind {
entry:
; CHECK-LABEL: t:
; CHECK: vpop {d8}
; CHECK-NOT: vpopne
; CHECK: pop {r7, pc}
; CHECK: vpop {d8}
; CHECK: pop {r7, pc}
br i1 undef, label %if.else, label %if.then
if.then: ; preds = %entry
%mul73 = fmul double undef, 0.000000e+00
%sub76 = fsub double %mul73, undef
store double %sub76, double* undef, align 4
%call88 = tail call double @cos(double 0.000000e+00) nounwind
%mul89 = fmul double undef, %call88
%sub92 = fsub double %mul89, undef
store double %sub92, double* undef, align 4
ret void
if.else: ; preds = %entry
%tmp101 = tail call double @llvm.pow.f64(double undef, double 0x3FD5555555555555)
%add112 = fadd double %tmp101, undef
%mul118 = fmul double %add112, undef
store double 0.000000e+00, double* %x, align 4
ret void
}
declare double @acos(double)
declare double @sqrt(double) readnone
declare double @cos(double) readnone
declare double @fabs(double)
declare double @llvm.pow.f64(double, double) nounwind readonly