File: nocapture.ll

package info (click to toggle)
llvm-toolchain-20 1%3A20.1.6-1~exp1
  • links: PTS, VCS
  • area: main
  • in suites: experimental
  • size: 2,111,304 kB
  • sloc: cpp: 7,438,677; ansic: 1,393,822; asm: 1,012,926; python: 241,650; f90: 86,635; objc: 75,479; lisp: 42,144; pascal: 17,286; sh: 10,027; ml: 5,082; perl: 4,730; awk: 3,523; makefile: 3,349; javascript: 2,251; xml: 892; fortran: 672
file content (36 lines) | stat: -rw-r--r-- 1,074 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
 
; RUN: opt < %s -aa-pipeline=basic-aa -passes=gvn,instcombine -S | FileCheck %s

declare ptr @test(ptr nocapture)

define i32 @test2() {
; CHECK: ret i32 0
       %P = alloca i32
       %Q = call ptr @test(ptr %P)
       %a = load i32, ptr %P
       store i32 4, ptr %Q   ;; cannot clobber P since it is nocapture.
       %b = load i32, ptr %P
       %c = sub i32 %a, %b
       ret i32 %c
}

declare void @test3(ptr %p, ptr %q) nounwind

define i32 @test4(ptr noalias nocapture %p) nounwind {
; CHECK: call void @test3
; CHECK: store i32 0, ptr %p
; CHECK: store i32 1, ptr %x
; CHECK: %y = load i32, ptr %p
; CHECK: ret i32 %y
entry:
       %q = alloca ptr
       ; Here test3 might store %p to %q. This doesn't violate %p's nocapture
       ; attribute since the copy doesn't outlive the function.
       call void @test3(ptr %q, ptr %p) nounwind
       store i32 0, ptr %p
       %x = load ptr, ptr %q
       ; This store might write to %p and so we can't eliminate the subsequent
       ; load
       store i32 1, ptr %x
       %y = load i32, ptr %p
       ret i32 %y
}