[llvm] [SelectionDAG] Add expansion for llvm.convert.from.arbitrary.fp (PR #179318)

[Matt Arsenault via llvm-commits]

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@@ -6085,6 +6086,18 @@ bool APFloatBase::isValidArbitraryFPFormat(StringRef Format) {
   return llvm::is_contained(ValidFormats, Format);
 }
 
+const fltSemantics *APFloatBase::getArbitraryFPSemantics(StringRef Format) {
+  // TODO: extend to remaining arbitrary FP types: Float8E4M3, Float8E3M4,
+  // Float8E5M2FNUZ, Float8E4M3FNUZ, Float8E4M3B11FNUZ, Float8E8M0FNU.
+  return StringSwitch<const fltSemantics *>(Format)
+      .Case("Float8E5M2", &semFloat8E5M2)
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arsenm wrote:

I'd expect these to be all lowercase (although maybe that mistake was in the original intrinsic patch)

https://github.com/llvm/llvm-project/pull/179318