File: preserve-sminmax.ll

package info (click to toggle)
llvm-toolchain-7 1%3A7.0.1-8
  • links: PTS, VCS
  • area: main
  • in suites: buster
  • size: 733,456 kB
  • sloc: cpp: 3,776,651; ansic: 633,271; asm: 350,301; python: 142,716; objc: 107,612; sh: 22,626; lisp: 11,056; perl: 7,999; pascal: 6,742; ml: 5,537; awk: 3,536; makefile: 2,557; cs: 2,027; xml: 841; ruby: 156
file content (32 lines) | stat: -rw-r--r-- 857 bytes parent folder | download | duplicates (23)
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
; RUN: opt < %s -instcombine -S | FileCheck %s

; Instcombine normally would fold the sdiv into the comparison,
; making "icmp slt i32 %h, 2", but in this case the sdiv has
; another use, so it wouldn't a big win, and it would also
; obfuscate an otherise obvious smax pattern to the point where
; other analyses wouldn't recognize it.

define i32 @foo(i32 %h) {
  %sd = sdiv i32 %h, 2
  %t = icmp slt i32 %sd, 1
  %r = select i1 %t, i32 %sd, i32 1
  ret i32 %r
}

; CHECK:  %sd = sdiv i32 %h, 2
; CHECK:  %t = icmp slt i32 %sd, 1
; CHECK:  %r = select i1 %t, i32 %sd, i32 1
; CHECK:  ret i32 %r

define i32 @bar(i32 %h) {
  %sd = sdiv i32 %h, 2
  %t = icmp sgt i32 %sd, 1
  %r = select i1 %t, i32 %sd, i32 1
  ret i32 %r
}

; CHECK:  %sd = sdiv i32 %h, 2
; CHECK:  %t = icmp sgt i32 %sd, 1
; CHECK:  %r = select i1 %t, i32 %sd, i32 1
; CHECK:  ret i32 %r