https://bugs.llvm.org/show_bug.cgi?id=50589
Bug ID: 50589
Summary: [Inliner] Noalias metadata incorrectly added to
simplified calls
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: Interprocedural Optimizations
Assignee: unassignedb...@nondot.org
Reporter: nikita....@gmail.com
CC: jeroen.dobbela...@synopsys.com,
llvm-bugs@lists.llvm.org
>From https://reviews.llvm.org/D102110#inline-972360:
define <2 x i8> @callee(<2 x i8>* %ptr1, <2 x i8>* noalias %ptr2, <2 x i1>
%mask, <2 x i8> %passthru) {
%ret = call <2 x i8> @llvm.masked.load.v2i8(<2 x i8>* %ptr1, i32 1, <2 x i1>
%mask, <2 x i8> %passthru)
store <2 x i8> zeroinitializer, <2 x i8>* %ptr2
ret <2 x i8> %ret
}
define void @caller(<2 x i8>* %ptr1, <2 x i8>* %ptr2) {
%passthru = load <2 x i8>, <2 x i8>* %ptr2
call <2 x i8> @callee(<2 x i8>* %ptr1, <2 x i8>* %ptr2, <2 x i1>
zeroinitializer, <2 x i8> %passthru)
ret void
}
declare <2 x i8> @llvm.masked.load.v2i8(<2 x i8>*, i32, <2 x i1>, <2 x i8>)
Results in:
define <2 x i8> @callee(<2 x i8>* %ptr1, <2 x i8>* noalias %ptr2, <2 x i1>
%mask, <2 x i8> %passthru) {
%ret = call <2 x i8> @llvm.masked.load.v2i8.p0v2i8(<2 x i8>* %ptr1, i32 1, <2
x i1> %mask, <2 x i8> %passthru)
store <2 x i8> zeroinitializer, <2 x i8>* %ptr2, align 2
ret <2 x i8> %ret
}
define void @caller(<2 x i8>* %ptr1, <2 x i8>* %ptr2) {
%passthru = load <2 x i8>, <2 x i8>* %ptr2, align 2, !noalias !0
call void @llvm.experimental.noalias.scope.decl(metadata !0)
store <2 x i8> zeroinitializer, <2 x i8>* %ptr2, align 2, !alias.scope !0
ret void
}
In this case, we don't even need the incorrect annotation to go on an
instruction from the caller, it can also happen with a callee instruction:
define <2 x i8> @callee(<2 x i8>* %ptr1, <2 x i8>* noalias %ptr2, <2 x i1>
%mask) {
%passthru = load <2 x i8>, <2 x i8>* %ptr2
%ret = call <2 x i8> @llvm.masked.load.v2i8(<2 x i8>* %ptr1, i32 1, <2 x i1>
%mask, <2 x i8> %passthru)
store <2 x i8> zeroinitializer, <2 x i8>* %ptr2
ret <2 x i8> %ret
}
define void @caller(<2 x i8>* %ptr1, <2 x i8>* %ptr2) {
call <2 x i8> @callee(<2 x i8>* %ptr1, <2 x i8>* %ptr2, <2 x i1>
zeroinitializer)
ret void
}
declare <2 x i8> @llvm.masked.load.v2i8(<2 x i8>*, i32, <2 x i1>, <2 x i8>)
Results in:
define <2 x i8> @callee(<2 x i8>* %ptr1, <2 x i8>* noalias %ptr2, <2 x i1>
%mask) {
%passthru = load <2 x i8>, <2 x i8>* %ptr2, align 2
%ret = call <2 x i8> @llvm.masked.load.v2i8.p0v2i8(<2 x i8>* %ptr1, i32 1, <2
x i1> %mask, <2 x i8> %passthru)
store <2 x i8> zeroinitializer, <2 x i8>* %ptr2, align 2
ret <2 x i8> %ret
}
define void @caller(<2 x i8>* %ptr1, <2 x i8>* %ptr2) {
call void @llvm.experimental.noalias.scope.decl(metadata !0)
%passthru.i = load <2 x i8>, <2 x i8>* %ptr2, align 2, !alias.scope !0,
!noalias !0
store <2 x i8> zeroinitializer, <2 x i8>* %ptr2, align 2, !alias.scope !0
ret void
}
Note how the metadata is claiming that the load does not alias ... with itself.
We should not be adding noalias metadata to instructions that are the result of
simplification, as they may not correspond to the instruction from the original
function.
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