From 3da00806215c2fa704c404d9ac151101d56e5817 Mon Sep 17 00:00:00 2001
From: Fabio Luporini <fabio@devitocodes.com>
Date: Wed, 18 Dec 2024 08:39:16 +0000
Subject: [PATCH] compiler: Generate fminf/fmaxf where necessary

---
 devito/symbolics/printer.py | 13 +++++++++----
 tests/test_symbolics.py     | 25 +++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/devito/symbolics/printer.py b/devito/symbolics/printer.py
index 8c31d4ecf7..12eb2baca4 100644
--- a/devito/symbolics/printer.py
+++ b/devito/symbolics/printer.py
@@ -101,20 +101,25 @@ def _print_Rational(self, expr):
     def _print_math_func(self, expr, nest=False, known=None):
         cls = type(expr)
         name = cls.__name__
-        if name not in self._prec_funcs:
-            return super()._print_math_func(expr, nest=nest, known=known)
 
         try:
             cname = self.known_functions[name]
         except KeyError:
             return super()._print_math_func(expr, nest=nest, known=known)
 
+        if cname not in self._prec_funcs:
+            return super()._print_math_func(expr, nest=nest, known=known)
+
         if self.single_prec(expr):
             cname = '%sf' % cname
 
-        args = ', '.join((self._print(arg) for arg in expr.args))
+        if nest and len(expr.args) > 2:
+            args = ', '.join([self._print(expr.args[0]),
+                              self._print_math_func(cls(*expr.args[1:]))])
+        else:
+            args = ', '.join([self._print(arg) for arg in expr.args])
 
-        return '%s(%s)' % (cname, args)
+        return f'{cname}({args})'
 
     def _print_Pow(self, expr):
         # Need to override because of issue #1627
diff --git a/tests/test_symbolics.py b/tests/test_symbolics.py
index 496e325387..b8c64ed410 100644
--- a/tests/test_symbolics.py
+++ b/tests/test_symbolics.py
@@ -562,6 +562,31 @@ def test_minmax():
     assert np.all(f.data == 4)
 
 
+@pytest.mark.parametrize('dtype,expected', [
+    (np.float32, ("fmaxf", "fminf")),
+    (np.float64, ("fmax", "fmin")),
+])
+def test_minmax_precision(dtype, expected):
+    grid = Grid(shape=(5, 5), dtype=dtype)
+
+    f = Function(name="f", grid=grid)
+    g = Function(name="g", grid=grid)
+
+    eqn = Eq(f, Min(g, 4.0) + Max(g, 2.0))
+
+    op = Operator(eqn)
+
+    g.data[:] = 3.0
+
+    op.apply()
+
+    # Check generated code -- ensure it's using the fp64 versions of min/max,
+    # that is fminf/fmaxf
+    assert all(i in str(op) for i in expected)
+
+    assert np.all(f.data == 6.0)
+
+
 class TestRelationsWithAssumptions:
 
     def test_multibounds_op(self):