Before this PR, weak linkage is applied to a few CLC generic functions
to allow target specific implementation to override generic one.
However, adding weak linkage has a side effect of preventing
inter-procedural optimization, such as PostOrderFunctionAttrsPass,
because weak function doesn't have exact definition (as determined by
hasExactDefinition in the pass).
This PR resolves the issue by adding --override flag for every
non-generic bitcode file in llvm-link run. This approach eliminates the
need for weak linkage while still allowing target-specific
implementation to override generic one.
llvm-diff shows imporoved attribute deduction for some functions in
amdgcn--amdhsa.bc, e.g.
%23 = tail call half @llvm.sqrt.f16(half %22)
=>
%23 = tail call noundef half @llvm.sqrt.f16(half %22)
28d9255aa7