[PATCH] D25305: [OpenCL] Setting constant address space for array initializers

[Anastasia Stulova via cfe-commits]

Anastasia added inline comments.


================
Comment at: lib/CodeGen/CGDecl.cpp:1272
+    if (getLangOpts().OpenCL) {
+      UA = llvm::GlobalValue::UnnamedAddr::None;
+      AS = CGM.getContext().getTargetAddressSpace(LangAS::opencl_constant);
----------------
AlexeySotkin wrote:
> bader wrote:
> > Anastasia wrote:
> > > bader wrote:
> > > > AlexeySotkin wrote:
> > > > > Anastasia wrote:
> > > > > > Why this change?
> > > > > Without this change, global variables with unnamed address space are translated to SPIR-V as variables with "Function" storage class, which is wrong.
> > > > > This should fix this issue: https://github.com/KhronosGroup/SPIRV-LLVM/issues/50
> > > > There is inconsistency with how Clang maps initializers to OpenCL memory model.
> > > > Consider example from the test case:
> > > > ```
> > > > __private int arr[] = {1, 2, 3};
> > > > ```
> > > > This code allocates a global constant for initializer {1, 2, 3} and later copies values from this global constant to the private array using memcpy intrinsic. The global constant must be allocated in constant address space, but old code do assign any address space, which is considered to be a private memory region.
> > > > This patch puts global constant objects to constant address space.
> > > Yes, this is perfectly fine. I was specifically asking about setting llvm::GlobalValue::UnnamedAddr::None attribute. I can't see why this has to be done or is it because we now assign concrete address space and private was treated as no address space at all?
> > This attribute has nothing to do with address spaces.
> > See http://llvm.org/docs/LangRef.html#global-variables for local_unnamed_addr and unnamed_addr attributes description.
> > My understanding is that llvm::GlobalValue::UnnamedAddr::Global should be fine here.
> llvm::GlobalValue::UnnamedAddr::None is default value of UnnamedAddr for GlobalValue. This line can be removed, but extra "if" statement must be added before GV->setUnnamedAddr(UA);
Yes, I also think that leaving global should be fine here. So could we just undo the change to line 1274?


https://reviews.llvm.org/D25305