[libspirv] Clone remangled functions on name clash (private default AS) #20889
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When the target’s default address space is private (e.g., SPIR), pointer address space remangling and long -> long long remangling can cause clone name collisions, preventing the remangled function from being cloned. Example: _Z1fPm -> remangled to _Z1fPU3AS0y; remangler clones back to _Z1fPm to preserve the original. Later, _Z1fPU3AS4m -> remangled to _Z1fPy; we need to clone _Z1fPy to _Z1fPm, but _Z1fPm already exists. Fix: Append a temporary suffix to avoid clashes (e.g., _Z1fPm$TmpSuffix). Remove the suffix in post-processing, replacing the old _Z1fPm (clone of _Z1fPU3AS0y) with the new remangled implementation. llvm-diff shows no change for targets whose default AS isn't private: remangled-l64-signed_char.libspirv-nvptx64-nvidia-cuda.bc and remangled-l64-unsigned_char.libspirv-amdgcn-amd-amdhsa.bc.
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When the target’s default address space is private (e.g., SPIR), simultaneous pointer address space remangling and long -> long long remangling can cause clone name collisions, preventing the remangled function from being cloned.
Example:
_Z1fPm -> remangled to _Z1fPU3AS0y; remangler clones back to _Z1fPm to preserve the original.
Later, _Z1fPU3AS4m -> remangled to _Z1fPy; we need to clone _Z1fPy to _Z1fPm, but _Z1fPm already exists.
Fix:
Append a temporary suffix to avoid clashes (e.g., _Z1fPm$TmpSuffix). Remove the suffix in post-processing, replacing the old _Z1fPm (clone of _Z1fPU3AS0y) with the new remangled implementation.
llvm-diff shows no change for targets whose default AS isn't private: remangled-l64-signed_char.libspirv-nvptx64-nvidia-cuda.bc and remangled-l64-unsigned_char.libspirv-amdgcn-amd-amdhsa.bc.