[llvm] SPIRV: Define runtime libcalls to be (almost) empty (PR #148631)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> What is the behavior change? (since this updated no tests, seems like are on paths we don't test?)

RuntimeLibcalls moves from reporting most every libcall as available to only these 2 are available.  The uses are largely on paths that generally shouldn't be reached in the first place, but RuntimeLibcalls is under-checked as it is today. In cases where a libcall is (incorrectly) emitted, this may change the failure mode

There are surely missing tests, it just happens the runtime libcall availability check only triggers on memcpy and memset (this is also a clue there is no test coverage for memmove).




https://github.com/llvm/llvm-project/pull/148631