https://llvm.org/bugs/show_bug.cgi?id=31896
Bug ID: 31896
Summary: ARM miscompilation of store of global alias
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: Backend: ARM
Assignee: unassignedb...@nondot.org
Reporter: eugeni.stepa...@gmail.com
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
$ cat q.ll
target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
target triple = "thumbv7--linux"
@X = constant {i8, i8 } { i8 0, i8 0 }
@XA = alias i8, getelementptr inbounds ({ i8, i8 }, {i8, i8}* @X, i32 0, i32 0)
@XB = alias i8, getelementptr inbounds ({ i8, i8 }, {i8, i8}* @X, i32 0, i32 1)
; not using alias - OK
define void @zzz(i8** %p) align 2 {
entry:
store i8* getelementptr inbounds ({ i8, i8 }, {i8, i8}* @X, i32 0, i32 1), i8
**%p, align 4
ret void
}
; store by alias. zzzA and zzzB generate identical code.
define void @zzzA(i8** %p) align 2 {
entry:
store i8* @XA, i8 **%p, align 4
ret void
}
define void @zzzB(i8** %p) align 2 {
entry:
store i8* @XB, i8 **%p, align 4
ret void
}
$ bin/llc q.ll -o -
zzz:
.fnstart
@ BB#0: @ %entry
movw r1, :lower16:X
movt r1, :upper16:X
adds r1, #1
str r1, [r0]
bx lr
zzzA:
.fnstart
@ BB#0: @ %entry
movw r1, :lower16:X
movt r1, :upper16:X
str r1, [r0]
bx lr
zzzB:
.fnstart
@ BB#0: @ %entry
movw r1, :lower16:X
movt r1, :upper16:X
str r1, [r0]
bx lr
Note how @XA and @XB are different, but assembly for @zzzA and @zzzB is the
same.
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