[libclc] [libclc] Move rsqrt to the CLC library (PR #129045)

[Fraser Cormack via cfe-commits]

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@@ -0,0 +1,4 @@
+__attribute__((weak)) _CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE
+__clc_rsqrt(__CLC_GENTYPE val) {
+  return __CLC_FP_LIT(1.0) / __clc_sqrt(val);
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frasercrmck wrote:

Good point. Perhaps we just use the elementwise sqrt builtin. I'm not sure I want to touch fast contract at such a scale right now.

https://github.com/llvm/llvm-project/pull/129045