[libclc] [libclc] Move logb/ilogb to CLC library; optimize (PR #128028)

[Matt Arsenault via cfe-commits]

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@@ -0,0 +1,73 @@
+#if __CLC_FPSIZE == 32
+
+_CLC_OVERLOAD _CLC_DEF __CLC_INTN __clc_ilogb(__CLC_GENTYPE x) {
+  __CLC_UINTN ux = __CLC_AS_UINTN(x);
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arsenm wrote:

although I guess this better if you have a dedicated frexp_exp instruction. Could factor out the frexp_exp part into a utility function, which does the bithacking or the intrinsic 

https://github.com/llvm/llvm-project/pull/128028