[all-commits] [llvm/llvm-project] e5a6a0: [SPIRV] Fix global emission for modules with no fu...

[Nick Sarnie via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: e5a6a0f10856b14ea0956b40305632fbbfea6f16
      https://github.com/llvm/llvm-project/commit/e5a6a0f10856b14ea0956b40305632fbbfea6f16
  Author: Nick Sarnie <nick.sarnie at intel.com>
  Date:   2026-03-04 (Wed, 04 Mar 2026)

  Changed paths:
    M llvm/lib/Target/SPIRV/SPIRVEmitIntrinsics.cpp
    M llvm/lib/Target/SPIRV/SPIRVPreLegalizer.cpp
    M llvm/lib/Target/SPIRV/SPIRVPrepareFunctions.cpp
    M llvm/lib/Target/SPIRV/SPIRVUtils.cpp
    M llvm/lib/Target/SPIRV/SPIRVUtils.h
    A llvm/test/CodeGen/SPIRV/global-var-no-functions.ll
    M llvm/test/CodeGen/SPIRV/legalize-zero-size-arrays-global.ll
    M llvm/test/CodeGen/SPIRV/legalize-zero-size-arrays-nested.ll
    M llvm/test/CodeGen/SPIRV/legalize-zero-size-arrays-struct.ll
    M llvm/test/CodeGen/SPIRV/legalize-zero-size-arrays-undef.ll

  Log Message:
  -----------
  [SPIRV] Fix global emission for modules with no functions (#183833)

Right now we have a problem where if you have a LLVM module with globals
but no functions, a completely empty SPIR-V module is emitted.

This is because global emission is dependent on tracking intrinsic
functions being emitted in functions.

As a simple fix, just insert a service function, which the backend is
already set up to not actually emit, if there are no real functions.

The current use case of the service function is for function pointers. I
don't think it's possible that we need to both generate a service
function for function pointers and for globals with no functions, so I
just added an error (not an assert) just in case if we do need it for
both cases.

Probably we should rework global handling in the future to work without
these workarounds, but this is a pretty fundamental issue so let's work
around it with this simple change for now.

This change exposed an existing bug:
  We consider basic blocks with no successors as fall-through

Also, fix some existing tests. The symptom was:
We previously emitted an empty module, but not that we don't, we hit a
`spirv-val` error about invalid Function StorageClass for globals
because no `addrspace` was specified. Set the `addrspace` to `1`
(`CrossWorkgroup`) in those tests.

Closes: https://github.com/llvm/llvm-project/issues/182899

---------

Signed-off-by: Nick Sarnie <nick.sarnie at intel.com>



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