[llvm] ARM: Remove remaining half convert libcall config into tablegen (PR #153408)

[Saleem Abdulrasool via llvm-commits]

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@@ -1497,6 +1490,27 @@ def ARMHalfConvertLibcallCallingConv : LibcallCallingConv<
     (isAAPCS_ABI(TT, ABIName) ? CallingConv::ARM_AAPCS : CallingConv::ARM_APCS)}]
 >;
 
+def ARMLibgccHalfConvertCalls :
+  LibcallImpls<(add __truncsfhf2, __extendhfsf2),
+    RuntimeLibcallPredicate<[{!TT.isTargetAEABI() && TT.isOSBinFormatMachO()}]>> {
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compnerd wrote:

I'm not sure I follow this - the old code would add these on !Watch ABI as either AAPCS or APCS.

https://github.com/llvm/llvm-project/pull/153408