diff mbox series

[Ada] Fix bogus error on conversion from Float to 128-bit unsigned

Message ID 20201022121212.GA4082@adacore.com
State New
Headers show
Series [Ada] Fix bogus error on conversion from Float to 128-bit unsigned | expand

Commit Message

Pierre-Marie de Rodat Oct. 22, 2020, 12:12 p.m. UTC 
The compiler confuses itself because it generates a range check in Float
whose upper bound is 2 ** 128, but this number is larger than the largest
number representable in Float so it triggers an error when converted to
Float as part of the check.

The fix is to saturate the upper bound of the check to that of Float.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

	* checks.adb (Apply_Float_Conversion_Check): Saturate the bounds
	of the check to those of the base type of the expression.
diff mbox series

Patch

diff --git a/gcc/ada/checks.adb b/gcc/ada/checks.adb
--- a/gcc/ada/checks.adb
+++ b/gcc/ada/checks.adb
@@ -2149,6 +2149,15 @@  package body Checks is
          Lo_OK := (Lo >= UR_From_Uint (Ifirst));
       end if;
 
+      --  Saturate the lower bound to that of the expression's type, because
+      --  we do not want to create an out-of-range value but we still need to
+      --  do a comparison to catch NaNs.
+
+      if Lo < Expr_Value_R (Type_Low_Bound (Expr_Type)) then
+         Lo := Expr_Value_R (Type_Low_Bound (Expr_Type));
+         Lo_OK := True;
+      end if;
+
       if Lo_OK then
 
          --  Lo_Chk := (X >= Lo)
@@ -2183,6 +2192,15 @@  package body Checks is
          Hi_OK := (Hi <= UR_From_Uint (Ilast));
       end if;
 
+      --  Saturate the higher bound to that of the expression's type, because
+      --  we do not want to create an out-of-range value but we still need to
+      --  do a comparison to catch NaNs.
+
+      if Hi > Expr_Value_R (Type_High_Bound (Expr_Type)) then
+         Hi := Expr_Value_R (Type_High_Bound (Expr_Type));
+         Hi_OK := True;
+      end if;
+
       if Hi_OK then
 
          --  Hi_Chk := (X <= Hi)