diff mbox series

[Ada] Disable wrong computation of offsets within multidimensional arrays

Message ID 20210621110533.GA41817@adacore.com
State New
Headers show
Series [Ada] Disable wrong computation of offsets within multidimensional arrays | expand

Commit Message

Pierre-Marie de Rodat June 21, 2021, 11:05 a.m. UTC 
Routine Indexed_Component_Bit_Offset is meant to return the first bit
position of an array component, but it only examined the first index
expression and necessarily produced wrong results for multidimensional
arrays.

Since this routine is only used for warnings, it is safe to simply
disable this wrong code and behave just like if the offsets within
a multidimensional array would not be known at compile time.

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

gcc/ada/

	* sem_util.adb (Indexed_Component_Bit_Offset): Return an unknown
	offset for components within multidimensional arrays; remove
	redundant parens.
diff mbox series

Patch

diff --git a/gcc/ada/sem_util.adb b/gcc/ada/sem_util.adb
--- a/gcc/ada/sem_util.adb
+++ b/gcc/ada/sem_util.adb
@@ -14827,6 +14827,12 @@  package body Sem_Util is
          return No_Uint;
       end if;
 
+      --  Do not attempt to compute offsets within multi-dimensional arrays
+
+      if Present (Next_Index (Ind)) then
+         return No_Uint;
+      end if;
+
       if Nkind (Ind) = N_Subtype_Indication then
          Ind := Constraint (Ind);
 
@@ -14843,7 +14849,7 @@  package body Sem_Util is
 
       --  Return the scaled offset
 
-      return Off * (Expr_Value (Exp) - Expr_Value (Low_Bound ((Ind))));
+      return Off * (Expr_Value (Exp) - Expr_Value (Low_Bound (Ind)));
    end Indexed_Component_Bit_Offset;
 
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