False positive with byval semantics when parameter is refined to readnone #1208
Description
FunctionAttrs refines the second argument of the following IR to readnone:
%struct.f = type { [1024 x i32] }
define void @src(ptr %0, ptr noundef byval(%struct.f) %1) {
call void @llvm.memset.p0.i64(ptr %0, i8 0, i64 4096, i1 false)
ret void
}
declare void @llvm.memset.p0.i64(ptr, i8, i64, i1)However Alive2 flags the refinement as invalid:
Transformation doesn't verify!
ERROR: Source is more defined than target
Example:
ptr %#0 = pointer(non-local, block_id=1, offset=0, attrs=8) / Address=#x0004
ptr byval(4096) noundef align(4) %#1 = pointer(non-local, block_id=1, offset=0, attrs=8) / Address=#x0004
Source:
SOURCE MEMORY STATE
===================
NON-LOCAL BLOCKS:
Block 0 > size: 0 align: 1 alloc type: 0 alive: false address: 0
Block 1 > size: 4096 align: 4 alloc type: 0 alive: true address: 4
Block 2 > size: 0 align: 1 alloc type: 0 alive: true address: 1
Target:
void = UB triggered!
Alive2: https://alive2.llvm.org/ce/z/qqfroB.