File: flags-multiuse.ll

package info (click to toggle)
llvm-toolchain-11 1%3A11.0.1-2
  • links: PTS, VCS
  • area: main
  • in suites: bullseye
  • size: 995,808 kB
  • sloc: cpp: 4,767,656; ansic: 760,916; asm: 477,436; python: 170,940; objc: 69,804; lisp: 29,914; sh: 23,855; f90: 18,173; pascal: 7,551; perl: 7,471; ml: 5,603; awk: 3,489; makefile: 2,573; xml: 915; cs: 573; fortran: 503; javascript: 452
file content (38 lines) | stat: -rw-r--r-- 1,030 bytes parent folder | download | duplicates (14) 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
 
; RUN: llc -mtriple=aarch64-none-linux-gnu -aarch64-enable-atomic-cfg-tidy=0 -verify-machineinstrs -o - %s | FileCheck %s

; LLVM should be able to cope with multiple uses of the same flag-setting
; instruction at different points of a routine. Either by rematerializing the
; compare or by saving and restoring the flag register.

declare void @bar()

@var = global i32 0

define i32 @test_multiflag(i32 %n, i32 %m, i32 %o) {
; CHECK-LABEL: test_multiflag:

  %test = icmp ne i32 %n, %m
; CHECK: cmp [[LHS:w[0-9]+]], [[RHS:w[0-9]+]]

  %val = zext i1 %test to i32
; CHECK: cset {{[xw][0-9]+}}, ne

; CHECK: mov [[RHSCOPY:w[0-9]+]], [[RHS]]
; CHECK: mov [[LHSCOPY:w[0-9]+]], [[LHS]]

  store i32 %val, i32* @var

  call void @bar()
; CHECK: bl bar

  ; Currently, the comparison is emitted again. An MSR/MRS pair would also be
  ; acceptable, but assuming the call preserves NZCV is not.
  br i1 %test, label %iftrue, label %iffalse
; CHECK: cmp [[LHSCOPY]], [[RHSCOPY]]
; CHECK: b.eq

iftrue:
  ret i32 42
iffalse:
  ret i32 0
}