[llvm] [TLI] Add basic support for nextafter/nexttoward libcalls (PR #166250)

[Sayan Sivakumaran via llvm-commits]

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@@ -1951,6 +1951,36 @@ TLI_DEFINE_ENUM_INTERNAL(nearbyintl)
 TLI_DEFINE_STRING_INTERNAL("nearbyintl")
 TLI_DEFINE_SIG_INTERNAL(LDbl, LDbl)
 
+/// double nextafter(double x, double y);
+TLI_DEFINE_ENUM_INTERNAL(nextafter)
+TLI_DEFINE_STRING_INTERNAL("nextafter")
+TLI_DEFINE_SIG_INTERNAL(Dbl, Dbl, Dbl)
+
+/// float nextafterf(float x, float y);
+TLI_DEFINE_ENUM_INTERNAL(nextafterf)
+TLI_DEFINE_STRING_INTERNAL("nextafterf")
+TLI_DEFINE_SIG_INTERNAL(Flt, Flt, Flt)
+
+/// long double nextafterl(long double x, long double y);
+TLI_DEFINE_ENUM_INTERNAL(nextafterl)
+TLI_DEFINE_STRING_INTERNAL("nextafterl")
+TLI_DEFINE_SIG_INTERNAL(LDbl, LDbl, LDbl)
+
+/// double nexttoward(double x, long double y);
+TLI_DEFINE_ENUM_INTERNAL(nexttoward)
+TLI_DEFINE_STRING_INTERNAL("nexttoward")
+TLI_DEFINE_SIG_INTERNAL(Dbl, Dbl, LDbl)
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sivakusayan wrote:

I believe the prototypes are correct according to the [manpage](https://man7.org/linux/man-pages/man3/nextafter.3.html), unless you mean something else.

https://github.com/llvm/llvm-project/pull/166250