fix: NO FMA build

Signed-off-by: Krishna Pandey <[email protected]>

Author: krishna2803

libc/src/math/generic/CMakeLists.txt

@@ -2250,6 +2250,7 @@ add_entrypoint_object(
     libc.src.__support.FPUtil.multiply_add
     libc.src.__support.FPUtil.polyeval
     libc.src.__support.macros.optimization
+    libc.src.__support.macros.properties.cpu_features
 )
 
 add_entrypoint_object(

libc/src/math/generic/log_bf16.cpp

@@ -14,6 +14,7 @@
 #include "src/__support/common.h"
 #include "src/__support/macros/config.h"
 #include "src/__support/macros/optimization.h"
+#include "src/__support/macros/properties/cpu_features.h"
 
 namespace LIBC_NAMESPACE_DECL {
 
@@ -99,6 +100,13 @@ LLVM_LIBC_FUNCTION(bfloat16, log_bf16, (bfloat16 x)) {
     return FPBits::inf().get_val();
   }
 
+#ifndef LIBC_TARGET_CPU_HAS_FMA
+  // log(0.00000000000000171390679426508540927898138761520386)
+  //     ~= -34.00000095
+  if (LIBC_UNLIKELY(x_u == 0x26F7U))
+    return bfloat16(-34.0000009);
+#endif // LIBC_TARGET_CPU_HAS_FMA
+
   int e = -FPBits::EXP_BIAS;
 
   // When x is subnormal, normalize it.