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| author | Arnaud Charlet <charlet@adacore.com> | 2021-01-29 10:57:39 -0500 |
|---|---|---|
| committer | Pierre-Marie de Rodat <derodat@adacore.com> | 2021-05-07 05:28:58 -0400 |
| commit | fde5868f3667b2ec0fb43c1b6f8c737be549fcce (patch) | |
| tree | 4ac9b362df9ce57c8e54f770fd7bbe0a65c47b7f /gcc | |
| parent | f3a8f939ba0473156f6c932f1acba2428e640011 (diff) | |
| download | gcc-fde5868f3667b2ec0fb43c1b6f8c737be549fcce.zip gcc-fde5868f3667b2ec0fb43c1b6f8c737be549fcce.tar.gz gcc-fde5868f3667b2ec0fb43c1b6f8c737be549fcce.tar.bz2 | |
[Ada] Computation of Shift_Left and large signed values
gcc/ada/
* sem_eval.adb (Fold_Shift): Fix computation of Shift_Left
resulting in negative signed values.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ada/sem_eval.adb | 36 |
1 files changed, 19 insertions, 17 deletions
diff --git a/gcc/ada/sem_eval.adb b/gcc/ada/sem_eval.adb index 7931015..2f1acc7 100644 --- a/gcc/ada/sem_eval.adb +++ b/gcc/ada/sem_eval.adb @@ -4983,7 +4983,7 @@ package body Sem_Eval is end if; end Check_Elab_Call; - Modulus : Uint; + Modulus, Val : Uint; begin if Compile_Time_Known_Value (Left) @@ -4994,23 +4994,25 @@ package body Sem_Eval is if Op = N_Op_Shift_Left then Check_Elab_Call; - declare - Modulus : Uint; - begin - if Is_Modular_Integer_Type (Typ) then - Modulus := Einfo.Modulus (Typ); - else - Modulus := Uint_2 ** RM_Size (Typ); - end if; + if Is_Modular_Integer_Type (Typ) then + Modulus := Einfo.Modulus (Typ); + else + Modulus := Uint_2 ** RM_Size (Typ); + end if; - -- Fold Shift_Left (X, Y) by computing (X * 2**Y) rem modulus + -- Fold Shift_Left (X, Y) by computing + -- (X * 2**Y) rem modulus [- Modulus] - Fold_Uint - (N, - (Expr_Value (Left) * (Uint_2 ** Expr_Value (Right))) - rem Modulus, - Static => Static); - end; + Val := (Expr_Value (Left) * (Uint_2 ** Expr_Value (Right))) + rem Modulus; + + if Is_Modular_Integer_Type (Typ) + or else Val < Modulus / Uint_2 + then + Fold_Uint (N, Val, Static => Static); + else + Fold_Uint (N, Val - Modulus, Static => Static); + end if; elsif Op = N_Op_Shift_Right then Check_Elab_Call; @@ -5042,7 +5044,7 @@ package body Sem_Eval is Check_Elab_Call; declare - Two_Y : constant Uint := Uint_2 ** Expr_Value (Right); + Two_Y : constant Uint := Uint_2 ** Expr_Value (Right); begin if Is_Modular_Integer_Type (Typ) then Modulus := Einfo.Modulus (Typ); |