Fix FTZ/DAZ.

Author: lntue

libc/src/math/generic/asin.cpp

@@ -56,7 +56,7 @@ LLVM_LIBC_FUNCTION(double, asin, (double x)) {
 #elif defined(LIBC_TARGET_CPU_HAS_FMA_DOUBLE)
       return fputil::multiply_add(x, 0x1.0p-54, x);
 #else
-      if (x == 0.0)
+      if (xbits.abs().uintval() == 0)
         return x;
       // Get sign(x) * min_normal.
       FPBits eps_bits = FPBits::min_normal();

libc/test/src/math/smoke/asin_test.cpp

@@ -36,13 +36,13 @@ TEST_F(LlvmLibcAsinTest, FTZMode) {
 TEST_F(LlvmLibcAsinTest, DAZMode) {
   ModifyMXCSR mxcsr(DAZ);
 
-  EXPECT_FP_EQ(min_denormal, LIBC_NAMESPACE::asin(min_denormal));
+  EXPECT_FP_EQ(zero, LIBC_NAMESPACE::asin(min_denormal));
 }
 
 TEST_F(LlvmLibcAsinTest, FTZDAZMode) {
   ModifyMXCSR mxcsr(FTZ | DAZ);
 
-  EXPECT_FP_EQ(min_denormal, LIBC_NAMESPACE::asin(min_denormal));
+  EXPECT_FP_EQ(zero, LIBC_NAMESPACE::asin(min_denormal));
 }
 
 #endif