Add cr_log from CORE-Math

Author: tgross35

libm-test/src/generate/case_list.rs

@@ -18,7 +18,6 @@ pub struct TestCase<Op: MathOp> {
 }
 
 impl<Op: MathOp> TestCase<Op> {
-    #[expect(dead_code)]
     fn append_inputs(v: &mut Vec<Self>, l: &[Op::RustArgs]) {
         v.extend(l.iter().copied().map(|input| Self {
             input,
@@ -532,7 +531,17 @@ fn lgammaf_r_cases() -> Vec<TestCase<op::lgammaf_r::Routine>> {
 }
 
 fn log_cases() -> Vec<TestCase<op::log::Routine>> {
-    vec![]
+    let mut v = Vec::new();
+    TestCase::append_inputs(
+        &mut v,
+        &[
+            // Cases that showed up during extensive tests and proved problematic
+            (hf64!("0x1.ffffffffffff9p-1"),),
+            (hf64!("0x1.4b649a5ce2720p-235"),),
+            (hf64!("0x1.b028b028b02a0p-1"),),
+        ],
+    );
+    v
 }
 
 fn log10_cases() -> Vec<TestCase<op::log10::Routine>> {

libm-test/src/precision.rs

@@ -48,6 +48,7 @@ pub fn default_ulp(ctx: &CheckCtx) -> u32 {
 
         // Operations that aren't required to be exact, but our implementations are.
         Bn::Cbrt => 0,
+        Bn::Log if ctx.fn_ident == Id::Log => 0,
 
         // Bessel functions have large inaccuracies.
         Bn::J0 | Bn::J1 | Bn::Y0 | Bn::Y1 | Bn::Jn | Bn::Yn => 8_000_000,
@@ -98,6 +99,7 @@ pub fn default_ulp(ctx: &CheckCtx) -> u32 {
 
         match ctx.fn_ident {
             Id::Cbrt => ulp = 2,
+            Id::Log => ulp = 2,
             // FIXME(#401): musl has an incorrect result here.
             Id::Fdim => ulp = 2,
             Id::Sincosf => ulp = 500,