Add TargetLibraryInfo pass to CPU LLVM pipeline.

The TLI pass makes sure that the optimisations that take place
during call simplification are appropriate for the target, without
this the target is assumed to be Linux and code will be optimised
to produce e.g. math symbols that do not exit on Windows.

This addresses numba#8898 in a more performant manner, it is almost a
total revert of numba#8907 (original fix for numba#8898), only the test
cases are kept.

docs/upcoming_changes/9336.improvement.rst

@@ -0,0 +1,11 @@
+Add ``TargetLibraryInfo`` pass to CPU LLVM pipeline.
+""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+The ``TargetLibraryInfo`` pass makes sure that the optimisations that take place
+during call simplification are appropriate for the target, without this the
+target is assumed to be Linux and code will be optimised to produce e.g. math
+symbols that do not exit on Windows. Historically this issue has been avoided
+through the use of Numba internal libraries carrying wrapped symbols, but doing
+so potentially detriments performance. As a result of this change Numba internal
+libraries are smaller and there is an increase in optimisation opportunity in
+code using ``exp2`` and ``log2`` functions.

numba/_helperlib.c

@@ -122,30 +122,6 @@ numba_ldexpf(float x, int exp)
     return x;
 }
 
-NUMBA_EXPORT_FUNC(double)
-numba_exp2(double x)
-{
-    return exp2(x);
-}
-
-NUMBA_EXPORT_FUNC(float)
-numba_exp2f(float x)
-{
-    return exp2f(x);
-}
-
-NUMBA_EXPORT_FUNC(double)
-numba_log2(double x)
-{
-    return log2(x);
-}
-
-NUMBA_EXPORT_FUNC(float)
-numba_log2f(float x)
-{
-    return log2f(x);
-}
-
 /* provide complex power */
 NUMBA_EXPORT_FUNC(void)
 numba_cpow(Py_complex *a, Py_complex *b, Py_complex *out) {

numba/_helpermod.c

@@ -55,10 +55,6 @@ build_c_helpers_dict(void)
     declmethod(frexpf);
     declmethod(ldexp);
     declmethod(ldexpf);
-    declmethod(exp2);
-    declmethod(exp2f);
-    declmethod(log2);
-    declmethod(log2f);
     declmethod(cpow);
     declmethod(cpowf);
     declmethod(erf);

numba/core/codegen.py

@@ -1225,6 +1225,7 @@ def _create_empty_module(self, name):
 
     def _module_pass_manager(self, **kwargs):
         pm = ll.create_module_pass_manager()
+        pm.add_target_library_info(ll.get_process_triple())
         self._tm.add_analysis_passes(pm)
         cost = kwargs.pop("cost", None)
         with self._pass_manager_builder(**kwargs) as pmb:
@@ -1256,6 +1257,7 @@ def _module_pass_manager(self, **kwargs):
 
     def _function_pass_manager(self, llvm_module, **kwargs):
         pm = ll.create_function_pass_manager(llvm_module)
+        pm.add_target_library_info(llvm_module.triple)
         self._tm.add_analysis_passes(pm)
         with self._pass_manager_builder(**kwargs) as pmb:
             pmb.populate(pm)

numba/np/npyfuncs.py

@@ -648,13 +648,11 @@ def np_complex_exp_impl(context, builder, sig, args):
 def np_real_exp2_impl(context, builder, sig, args):
     _check_arity_and_homogeneity(sig, args, 1)
 
-    dispatch_table = {
-        types.float32: 'numba_exp2f',
-        types.float64: 'numba_exp2',
-    }
-
-    return _dispatch_func_by_name_type(context, builder, sig, args,
-                                       dispatch_table, 'exp2')
+    ll_ty = args[0].type
+    fnty = llvmlite.ir.FunctionType(ll_ty, [ll_ty,])
+    fn = cgutils.insert_pure_function(builder.module, fnty,
+                                      name='llvm.exp2')
+    return builder.call(fn, [args[0]])
 
 
 def np_complex_exp2_impl(context, builder, sig, args):
@@ -687,13 +685,11 @@ def np_complex_log_impl(context, builder, sig, args):
 def np_real_log2_impl(context, builder, sig, args):
     _check_arity_and_homogeneity(sig, args, 1)
 
-    dispatch_table = {
-        types.float32: 'numba_log2f',
-        types.float64: 'numba_log2',
-    }
-
-    return _dispatch_func_by_name_type(context, builder, sig, args,
-                                       dispatch_table, 'log2')
+    ll_ty = args[0].type
+    fnty = llvmlite.ir.FunctionType(ll_ty, [ll_ty,])
+    fn = cgutils.insert_pure_function(builder.module, fnty,
+                                      name='llvm.log2')
+    return builder.call(fn, [args[0]])
 
 def np_complex_log2_impl(context, builder, sig, args):
     _check_arity_and_homogeneity(sig, args, 1)

numba/tests/npyufunc/test_ufunc.py

@@ -145,7 +145,7 @@ class TestUFuncsMisc(TestCase):
     # Test for miscellaneous ufunc issues
 
     def test_exp2(self):
-        # See issue #8898
+        # See issue #8898, and TargetLibraryInfo based fix in #9336
         @njit
         def foo(x):
             return np.exp2(x)
@@ -157,7 +157,7 @@ def foo(x):
             self.assertPreciseEqual(expected, got)
 
     def test_log2(self):
-        # See issue #8898
+        # See issue #8898, and TargetLibraryInfo based fix in #9336
         @njit
         def foo(x):
             return np.log2(x)