[gcc r12-550] [Ada] Do not second-guess the hardware for underflow handling of Scaling

[gcc r12-550] [Ada] Do not second-guess the hardware for underflow handling of Scaling

[Pierre-Marie de Rodat]

https://gcc.gnu.org/g:b6f9471df1a4c22de519c7049a390235508bbee9

commit r12-550-gb6f9471df1a4c22de519c7049a390235508bbee9
Author: Eric Botcazou <ebotcazou@adacore.com>
Date:   Thu Jan 21 13:12:50 2021 +0100

    [Ada] Do not second-guess the hardware for underflow handling of Scaling
    
    gcc/ada/
    
            * libgnat/s-fatgen.adb (Scaling): Use single handling of
            underflow.  Add pragma Annotate.

Diff:
---
 gcc/ada/libgnat/s-fatgen.adb | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/gcc/ada/libgnat/s-fatgen.adb b/gcc/ada/libgnat/s-fatgen.adb
index 145d4ac9b0e..ec376e73e45 100644
--- a/gcc/ada/libgnat/s-fatgen.adb
+++ b/gcc/ada/libgnat/s-fatgen.adb
@@ -781,11 +781,9 @@ package body System.Fat_Gen is
          --  Check for underflow
 
          elsif Adjustment < IEEE_Emin - Exp then
-            --  Check for gradual underflow
+            --  Check for possibly gradual underflow (up to the hardware)
 
-            if T'Denorm
-              and then Adjustment >= IEEE_Emin - Mantissa - Exp
-            then
+            if Adjustment >= IEEE_Emin - Mantissa - Exp then
                Expf := IEEE_Emin;
                Expi := Exp + Adjustment - Expf;
 
@@ -810,6 +808,9 @@ package body System.Fat_Gen is
             --  Given that Expi >= -Mantissa, only -64 is problematic
 
             if Expi = -64 then
+               pragma Annotate
+                 (CodePeer, Intentional, "test always false",
+                  "test always false in some instantiations");
                XX := XX / 2.0;
                Expi := -63;
             end if;