llvm/test/CodeGen/AArch64/jump-table.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

66 lines
1.8 KiB
LLVM

; RUN: llc -verify-machineinstrs -o - %s -mtriple=aarch64-none-linux-gnu -aarch64-atomic-cfg-tidy=0 | FileCheck %s
; RUN: llc -code-model=large -verify-machineinstrs -o - %s -mtriple=aarch64-none-linux-gnu -aarch64-atomic-cfg-tidy=0 | FileCheck --check-prefix=CHECK-LARGE %s
; RUN: llc -mtriple=aarch64-none-linux-gnu -verify-machineinstrs -relocation-model=pic -aarch64-atomic-cfg-tidy=0 -o - %s | FileCheck --check-prefix=CHECK-PIC %s
define i32 @test_jumptable(i32 %in) {
; CHECK: test_jumptable
switch i32 %in, label %def [
i32 0, label %lbl1
i32 1, label %lbl2
i32 2, label %lbl3
i32 4, label %lbl4
]
; CHECK: adrp [[JTPAGE:x[0-9]+]], .LJTI0_0
; CHECK: add x[[JT:[0-9]+]], [[JTPAGE]], {{#?}}:lo12:.LJTI0_0
; CHECK: ldr [[DEST:x[0-9]+]], [x[[JT]], {{x[0-9]+}}, lsl #3]
; CHECK: br [[DEST]]
; CHECK-LARGE: movz x[[JTADDR:[0-9]+]], #:abs_g3:.LJTI0_0
; CHECK-LARGE: movk x[[JTADDR]], #:abs_g2_nc:.LJTI0_0
; CHECK-LARGE: movk x[[JTADDR]], #:abs_g1_nc:.LJTI0_0
; CHECK-LARGE: movk x[[JTADDR]], #:abs_g0_nc:.LJTI0_0
; CHECK-LARGE: ldr [[DEST:x[0-9]+]], [x[[JTADDR]], {{x[0-9]+}}, lsl #3]
; CHECK-LARGE: br [[DEST]]
; CHECK-PIC: adrp [[JTPAGE:x[0-9]+]], .LJTI0_0
; CHECK-PIC: add x[[JT:[0-9]+]], [[JTPAGE]], {{#?}}:lo12:.LJTI0_0
; CHECK-PIC: ldrsw [[DEST:x[0-9]+]], [x[[JT]], {{x[0-9]+}}, lsl #2]
; CHECK-PIC: add [[TABLE:x[0-9]+]], [[DEST]], x[[JT]]
; CHECK-PIC: br [[TABLE]]
def:
ret i32 0
lbl1:
ret i32 1
lbl2:
ret i32 2
lbl3:
ret i32 4
lbl4:
ret i32 8
}
; CHECK: .rodata
; CHECK: .LJTI0_0:
; CHECK-NEXT: .xword
; CHECK-NEXT: .xword
; CHECK-NEXT: .xword
; CHECK-NEXT: .xword
; CHECK-NEXT: .xword
; CHECK-PIC-NOT: .data_region
; CHECK-PIC: .LJTI0_0:
; CHECK-PIC-NEXT: .word
; CHECK-PIC-NEXT: .word
; CHECK-PIC-NEXT: .word
; CHECK-PIC-NEXT: .word
; CHECK-PIC-NEXT: .word
; CHECK-PIC-NOT: .end_data_region