[PATCH] ubsan: Don't test for NaNs if those do not exist (PR97926)

[Segher Boessenkool]

Tested on powerpc64-linux {-m32,-m64}.  No regressions.  Is this okay
for trunk?


Segher


2021-03-19  Segher Boessenkool  <seg...@kernel.crashing.org>

        PR target/97926
        * ubsan.c (ubsan_instrument_float_cast): Don't test for unordered if
        there are no NaNs.
---
 gcc/ubsan.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/gcc/ubsan.c b/gcc/ubsan.c
index d752b897d642..1089aef639ff 100644
--- a/gcc/ubsan.c
+++ b/gcc/ubsan.c
@@ -1890,8 +1890,16 @@ ubsan_instrument_float_cast (location_t loc, tree type, 
tree expr)
   else
     return NULL_TREE;
 
-  t = fold_build2 (UNLE_EXPR, boolean_type_node, expr, min);
-  tt = fold_build2 (UNGE_EXPR, boolean_type_node, expr, max);
+  if (HONOR_NANS (mode))
+    {
+      t = fold_build2 (UNLE_EXPR, boolean_type_node, expr, min);
+      tt = fold_build2 (UNGE_EXPR, boolean_type_node, expr, max);
+    }
+  else
+    {
+      t = fold_build2 (LE_EXPR, boolean_type_node, expr, min);
+      tt = fold_build2 (GE_EXPR, boolean_type_node, expr, max);
+    }
   t = fold_build2 (TRUTH_OR_EXPR, boolean_type_node, t, tt);
   if (integer_zerop (t))
     return NULL_TREE;
-- 
1.8.3.1