[libc-commits] [libc] [libc][math] Speed up log2f subnormals and log10f table access (PR #223718)

via libc-commits libc-commits at lists.llvm.org
Fri Sep 25 08:08:34 PDT 2026


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@@ -91,7 +92,13 @@ LIBC_INLINE float log2f(float x) {
       return x;
     }
     // Normalize denormal inputs.
-    xbits = FPBits(xbits.get_val() * 0x1.0p23f);
+    int biased_exponent = 32 - cpp::countl_zero(x_u);
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lntue wrote:

This looks like will perform worse on CPUs with fast denormal multiplications?

https://github.com/llvm/llvm-project/pull/223718


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