[Ada] Fix problematic underflow for Float_Type'Value

We need a couple of guards for boundary conditions in the support code.

gcc/ada/

	* libgnat/s-dourea.adb ("/"): Add guard for zero and infinite
	divisor.
	* libgnat/s-valuer.adb (Scan_Raw_Real): Add guard for very large
	exponent values.

1 files changed, 12 insertions, 0 deletions

diff --git a/gcc/ada/libgnat/s-dourea.adb b/gcc/ada/libgnat/s-dourea.adb
index a6cf2a1..4f378d6 100644
--- a/gcc/ada/libgnat/s-dourea.adb
+++ b/gcc/ada/libgnat/s-dourea.adb
@@ -178,6 +178,12 @@ package body System.Double_Real is
       P, R   : Double_T;
 
    begin
+      if Is_Infinity (B) or else Is_Zero (B) then
+         return (A.Hi / B, 0.0);
+      end if;
+      pragma Annotate (CodePeer, Intentional, "test always false",
+                       "code deals with infinity");
+
       Q1 := A.Hi / B;
 
       --  Compute R = A - B * Q1
@@ -196,6 +202,12 @@ package body System.Double_Real is
       R, S       : Double_T;
 
    begin
+      if Is_Infinity (B.Hi) or else Is_Zero (B.Hi) then
+         return (A.Hi / B.Hi, 0.0);
+      end if;
+      pragma Annotate (CodePeer, Intentional, "test always false",
+                       "code deals with infinity");
+
       Q1 := A.Hi / B.Hi;
       R := A - B * Q1;