[Ada] Fix proof of double arithmetic units

Proof of an assertion is not automatic anymore. Add two assertions
before it to guide the prover.

gcc/ada/

	* libgnat/s-aridou.adb (Double_Divide): Add intermediate
	assertions.

diff --git a/gcc/ada/libgnat/s-aridou.adb b/gcc/ada/libgnat/s-aridou.adb
index ffb6f4c..08cbed7 100644 (file)
--- a/gcc/ada/libgnat/s-aridou.adb
+++ b/gcc/ada/libgnat/s-aridou.adb
@@ -941,11 +941,13 @@ is
          else
             T2 := Yhi * Zlo;
             pragma Assert (Big (T2) = Big (Double_Uns'(Yhi * Zlo)));
+            pragma Assert (Big_0 = Big (Double_Uns'(Ylo * Zhi)));
          end if;
 
       else
          T2 := Ylo * Zhi;
          pragma Assert (Big (T2) = Big (Double_Uns'(Ylo * Zhi)));
+         pragma Assert (Big_0 = Big (Double_Uns'(Yhi * Zlo)));
       end if;
 
       T1 := Ylo * Zlo;