[llvm] RuntimeLibcalls: Mostly move x86 configuration into tablegen (PR #148575)

[Matt Arsenault via llvm-commits]

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@@ -1151,7 +1187,10 @@ def isAArch64_ILP64  : RuntimeLibcallPredicate<"TT.isAArch64(64)">;
 
 def AArch64SystemLibrary : SystemRuntimeLibrary<
   isAArch64_ExceptArm64EC,
-  (add DefaultRuntimeLibcallImpls,
+  (add Win64DefaultLibcallImpls,
+       LibcallImpls<(add __powisf2, __powidf2), isNotOSMSVCRT>,
+       LibmHasFrexpF32, LibmHasLdexpF32,
+       LibmHasFrexpF128, LibmHasLdexpF128,
        AArch64LibcallImpls,
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arsenm wrote:

It's not, there are some isOSWindows in there.

This whole thing is also messier than it should be, it should improve once the list of calls is fully separated from the lowering decision 

https://github.com/llvm/llvm-project/pull/148575