[COMMITTED] ada: Clean up unnecesary call in resolution of overloaded expressions

["Marc Poulhiès" <poulhies@adacore.com>]

From: Piotr Trojanek <trojanek@adacore.com>

When experimentally enabling frontend inlining by default, the
unnecessary call to Comes_From_Predefined_Lib_Unit in Resolve appears to
be a performance bottleneck (most likely this call is expensive because
it involves a loop over the currently inlined subprograms).

Code cleanup; semantics is unaffected.

gcc/ada/

	* sem_res.adb (Resolve): Only call Comes_From_Predefined_Lib_Unit
	when its result might be needed.

Tested on x86_64-pc-linux-gnu, committed on master.

---
 gcc/ada/sem_res.adb | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/gcc/ada/sem_res.adb b/gcc/ada/sem_res.adb
index 76750708bca..ea9a03b58e6 100644
--- a/gcc/ada/sem_res.adb
+++ b/gcc/ada/sem_res.adb
@@ -2370,8 +2370,6 @@ package body Sem_Res is
            ("prefix must statically denote a non-remote subprogram", N);
       end if;
 
-      From_Lib := Comes_From_Predefined_Lib_Unit (N);
-
       --  If the context is a Remote_Access_To_Subprogram, access attributes
       --  must be resolved with the corresponding fat pointer. There is no need
       --  to check for the attribute name since the return type of an
@@ -2505,6 +2503,8 @@ package body Sem_Res is
       --  is compatible with the context (i.e. the type passed to Resolve)
 
       else
+         From_Lib := Comes_From_Predefined_Lib_Unit (N);
+
          --  Loop through possible interpretations
 
          Get_First_Interp (N, I, It);
-- 
2.34.1