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
39
40
41
42
43
44
45
46
47
48
49
50
51
|
; RUN: opt -S -basicaa -gvn < %s | FileCheck %s
declare void @argmemonly_function(i32 *) argmemonly
define i32 @test0(i32* %P, i32* noalias %P2) {
; CHECK-LABEL: @test0(
%v1 = load i32, i32* %P
; CHECK: %v1 = load i32, i32* %P
call void @argmemonly_function(i32* %P2) [ "tag"() ]
; CHECK: call void @argmemonly_function(
%v2 = load i32, i32* %P
; CHECK: %v2 = load i32, i32* %P
%diff = sub i32 %v1, %v2
; CHECK: %diff = sub i32 %v1, %v2
ret i32 %diff
; CHECK: ret i32 %diff
}
define i32 @test1(i32* %P, i32* noalias %P2) {
; CHECK-LABEL: @test1(
%v1 = load i32, i32* %P
call void @argmemonly_function(i32* %P2) argmemonly [ "tag"() ]
; CHECK: call void @argmemonly_function(
%v2 = load i32, i32* %P
%diff = sub i32 %v1, %v2
ret i32 %diff
; CHECK: ret i32 0
}
define i32 @test2(i32* %P, i32* noalias %P2) {
; Note: in this test we //can// GVN %v1 and %v2 into one value in theory. Calls
; with deopt operand bundles are not argmemonly because they *read* the entire
; heap, but they don't write to any location in the heap if the callee does not
; deoptimize the caller. This fact, combined with the fact that
; @argmemonly_function is, well, an argmemonly function, can be used to conclude
; that %P is not written to at the callsite. However LLVM currently cannot
; describe the "does not write to non-args, and reads the entire heap" effect on
; a callsite.
; CHECK-LABEL: @test2(
%v1 = load i32, i32* %P
; CHECK: %v1 = load i32, i32* %P
call void @argmemonly_function(i32* %P2) [ "deopt"() ]
; CHECK: call void @argmemonly_function(
%v2 = load i32, i32* %P
; CHECK: %v2 = load i32, i32* %P
%diff = sub i32 %v1, %v2
; CHECK: %diff = sub i32 %v1, %v2
ret i32 %diff
; CHECK: ret i32 %diff
}
|
