beanz added inline comments.
================
Comment at: clang/lib/CodeGen/CGHLSLRuntime.cpp:151
+ llvm::Module &M = CGM.getModule();
+ const auto *GlobalCtors = M.getNamedGlobal("llvm.global_ctors");
+ if (!GlobalCtors)
----------------
python3kgae wrote:
> beanz wrote:
> > python3kgae wrote:
> > > Don't need to generate CtorCalls for lib profile in clang codeGen.
> > > Have to do this when linking anyway.
> > Are you sure? The global constructors contain the `createHandle` calls for
> > resources, and DXC does currently generate those inside shader entries for
> > lib shaders.
> >
> > I'm sure we're not generating those _correctly_ with this change, but I
> > think we still need the constructor calls inside any function annotated
> > with the `[shader(...)]` attribute.
> I saw dxc did call ctor for all entries. Maybe to match the behavior, we need
> to do the same thing.
> But I don't understand why we must do that except to match what dxc does.
> Maybe we can also have a test for lib profile to make understanding things
> easier?
I can (and should) add a library shader test too.
In addition to the cases where DXC generates global constructors, we need them
in clang in more cases, because I'm using global constructors to reduce the
scope of changes HLSL needs in CodeGen.
In the case of global resource variables (as shown in the test in this PR), DXC
generates the handle creation calls with a bunch of custom code in clang
CodeGen, and inserts that code into the entry functions.
To avoid needing special code for handle creation in Clang, I've put handle
creation calls inside the constructors for the resource object. For global
definitions, the constructors then get called by the global initialization
function automatically, which we can inline into the entry.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D132977/new/
https://reviews.llvm.org/D132977
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