search for: devmemori

Hello, According to include/llvm/IR/Intrinsics.td, InstrReadMem property indicates that the intrinsic only reads from and does not write to memory. Does this mean that it can read anywhere in the memory? Because we already have 'InstrArgMemOnly' for intrinsics which only access memory that its argument(s) point(s) to. If 'InstrReadMem' really means read from anywhere in the

Hi Johannes, Thanks for your reply. I now see more clearly how things work with these properties. However, what would be an object whose address is potentially known by a callee? I suppose the intrinsic arguments and global variable? So IIUC, if not restricted by *only properties, an intrinsic could access to: - only its arguments if IntrArgMemOnly specified, - its arguments and the global

Ok, now I think I've found a bug: Consider this C code: void bar(int b) { int a[10]; memset(a, b, 10); } which generates this IR code: define dso_local void @bar(i32 %b) #0 { entry: %b.addr = alloca i32, align 4 %a = alloca [10 x i32], align 16 store i32 %b, i32* %b.addr, align 4 %arraydecay = getelementptr inbounds [10 x i32], [10 x i32]* %a, i64 0, i64 0 %0 = bitcast i32*

So I removed the 'tail' from the call and try out different properties: - IntrNoMem: memset() and the intrinsic are both optimized away as expected - IntrWriteMem: memset() optimized away by DSE but the intrinsic isn't. I would expect both to be removed, since the intrinsic is now also a dead store. - IntrReadMem: memset() and the intrinsic are both optimized away *unexpectedly* (CSE