qiucf added inline comments.
================
Comment at: clang/lib/CodeGen/CGBuiltin.cpp:100
+ static SmallDenseMap<unsigned, StringRef, 8> F128Builtins{
+ {Builtin::BI__builtin_printf, "__printfieee128"},
+ {Builtin::BI__builtin_vsnprintf, "__vsnprintfieee128"},
----------------
jsji wrote:
> Why only these printf builtins? I think there are full list of similar
> libcalls in `GLIBC_2.32` and later?
Yes, Glibc redirects all these functions depending on long double semantics,
and GCC has corresponding builtins for almost all library functions
(https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html).
But currently clang doesn't have all of these builtins (for example,
`__builtin_scanf`). It seems beyond this patch's scope to make the list
complete.
================
Comment at: clang/lib/CodeGen/CGBuiltin.cpp:117
+ if (getTriple().isPPC64() &&
+ &getTarget().getLongDoubleFormat() == &llvm::APFloat::IEEEquad() &&
+ F128Builtins.find(BuiltinID) != F128Builtins.end())
----------------
jsji wrote:
> How do we deal with the glibc version? Do we assume that user has glibc newer
> than GLIBC_2.32?
I notice not all libcall symbols are implemented in compiler-rt, which means we
don't need to always expect all libcalls emitted are available in current libc?
It's surprising that libc version are not checked in clang/driver/toolchain
part. The only place checking libc version is in
[sanitizer](https://github.com/llvm/llvm-project/blob/81441cf44c145e1d90a10c743e0190a44fbf8fcb/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp#L170).
Maybe we can use that to emit warnings, like D112906.
================
Comment at: clang/lib/CodeGen/CGBuiltin.cpp:119
+ F128Builtins.find(BuiltinID) != F128Builtins.end())
+ Name = F128Builtins[BuiltinID];
+ else
----------------
jsji wrote:
> Do we have to do it here? Can we just update the libcall names in
> `RuntimeLibcalls.def` or `setLibcallName` similar to others?
I think we cannot fill these calls in backend's runtime libcall list, because
it contains supplementary routine names for legalizing IR
instruction/intrinsics. Here the builtins are just converted into normal
function calls in IR.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D112401/new/
https://reviews.llvm.org/D112401
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