From 60440d3cf51acb9cb63543d5bb71fd50cfdd9470 Mon Sep 17 00:00:00 2001 From: Eric Botcazou Date: Wed, 13 Oct 2021 20:50:28 +0200 Subject: [PATCH] [Ada] Factor out machine rounding operations gcc/ada/ * sem_eval.ads (Machine_Number): New inline function. * sem_eval.adb (Machine_Number): New function body implementing the machine rounding operation specified by RM 4.9(38/2). (Check_Non_Static_Context): Call Machine_Number and set the Is_Machine_Number flag consistently on the resulting node. * sem_attr.adb (Eval_Attribute) : Likewise. * checks.adb (Apply_Float_Conversion_Check): Call Machine_Number. (Round_Machine): Likewise. --- gcc/ada/checks.adb | 8 ++++---- gcc/ada/sem_attr.adb | 8 +++----- gcc/ada/sem_eval.adb | 38 ++++++++++++++++++++++++-------------- gcc/ada/sem_eval.ads | 8 ++++++++ 4 files changed, 39 insertions(+), 23 deletions(-) diff --git a/gcc/ada/checks.adb b/gcc/ada/checks.adb index c06012b..c85cba9a5 100644 --- a/gcc/ada/checks.adb +++ b/gcc/ada/checks.adb @@ -2171,7 +2171,7 @@ package body Checks is Lo_OK := (Ifirst > 0); else - Lo := Machine (Expr_Type, UR_From_Uint (Ifirst), Round_Even, Expr); + Lo := Machine_Number (Expr_Type, UR_From_Uint (Ifirst), Expr); Lo_OK := (Lo >= UR_From_Uint (Ifirst)); end if; @@ -2214,7 +2214,7 @@ package body Checks is Hi := UR_From_Uint (Ilast) + Ureal_Half; Hi_OK := (Ilast < 0); else - Hi := Machine (Expr_Type, UR_From_Uint (Ilast), Round_Even, Expr); + Hi := Machine_Number (Expr_Type, UR_From_Uint (Ilast), Expr); Hi_OK := (Hi <= UR_From_Uint (Ilast)); end if; @@ -5563,7 +5563,7 @@ package body Checks is -- the results in Lo_Right, Hi_Right, Lo_Left, Hi_Left. function Round_Machine (B : Ureal) return Ureal; - -- B is a real bound. Round it using mode Round_Even. + -- B is a real bound. Round it to the nearest machine number. ----------------- -- OK_Operands -- @@ -5589,7 +5589,7 @@ package body Checks is function Round_Machine (B : Ureal) return Ureal is begin - return Machine (Typ, B, Round_Even, N); + return Machine_Number (Typ, B, N); end Round_Machine; -- Start of processing for Determine_Range_R diff --git a/gcc/ada/sem_attr.adb b/gcc/ada/sem_attr.adb index 32c5d37..f2bb12d 100644 --- a/gcc/ada/sem_attr.adb +++ b/gcc/ada/sem_attr.adb @@ -9251,14 +9251,12 @@ package body Sem_Attr is -- Machine -- ------------- - -- We use the same rounding mode as the one used for RM 4.9(38) + -- We use the same rounding as the one used for RM 4.9(38/2) when Attribute_Machine => Fold_Ureal - (N, - Eval_Fat.Machine - (P_Base_Type, Expr_Value_R (E1), Eval_Fat.Round_Even, N), - Static); + (N, Machine_Number (P_Base_Type, Expr_Value_R (E1), N), Static); + Set_Is_Machine_Number (N); ------------------ -- Machine_Emax -- diff --git a/gcc/ada/sem_eval.adb b/gcc/ada/sem_eval.adb index 954a4a6..e3308ef 100644 --- a/gcc/ada/sem_eval.adb +++ b/gcc/ada/sem_eval.adb @@ -523,8 +523,8 @@ package body Sem_Eval is and then Nkind (Parent (N)) in N_Subexpr then Rewrite (N, New_Copy (N)); - Set_Realval - (N, Machine (Base_Type (T), Realval (N), Round_Even, N)); + Set_Realval (N, Machine_Number (Base_Type (T), Realval (N), N)); + Set_Is_Machine_Number (N); end if; end if; @@ -575,18 +575,7 @@ package body Sem_Eval is (N, Corresponding_Integer_Value (N) * Small_Value (T)); elsif not UR_Is_Zero (Realval (N)) then - - -- Note: even though RM 4.9(38) specifies biased rounding, this - -- has been modified by AI-100 in order to prevent confusing - -- differences in rounding between static and non-static - -- expressions. AI-100 specifies that the effect of such rounding - -- is implementation dependent, and in GNAT we round to nearest - -- even to match the run-time behavior. Note that this applies - -- to floating point literals, not fixed points ones, even though - -- their compiler representation is also as a universal real. - - Set_Realval - (N, Machine (Base_Type (T), Realval (N), Round_Even, N)); + Set_Realval (N, Machine_Number (Base_Type (T), Realval (N), N)); Set_Is_Machine_Number (N); end if; @@ -6046,6 +6035,27 @@ package body Sem_Eval is end Is_Statically_Unevaluated; -------------------- + -- Machine_Number -- + -------------------- + + -- Historical note: RM 4.9(38) originally specified biased rounding but + -- this has been modified by AI-268 to prevent confusing differences in + -- rounding between static and nonstatic expressions. This AI specifies + -- that the effect of such rounding is implementation-dependent instead, + -- and in GNAT we round to nearest even to match the run-time behavior. + -- Note that this applies to floating-point literals, not fixed-point + -- ones, even though their representation is also a universal real. + + function Machine_Number + (Typ : Entity_Id; + Val : Ureal; + N : Node_Id) return Ureal + is + begin + return Machine (Typ, Val, Round_Even, N); + end Machine_Number; + + -------------------- -- Not_Null_Range -- -------------------- diff --git a/gcc/ada/sem_eval.ads b/gcc/ada/sem_eval.ads index c93d97d..c2e08b6 100644 --- a/gcc/ada/sem_eval.ads +++ b/gcc/ada/sem_eval.ads @@ -486,6 +486,13 @@ package Sem_Eval is -- it cannot be determined at compile time. Flag Fixed_Int is used as in -- routine Is_In_Range above. + function Machine_Number + (Typ : Entity_Id; + Val : Ureal; + N : Node_Id) return Ureal; + -- Return the machine number of Typ corresponding to the specified Val as + -- per RM 4.9(38/2). N is a node only used to post warnings. + function Not_Null_Range (Lo : Node_Id; Hi : Node_Id) return Boolean; -- Returns True if it can guarantee that Lo .. Hi is not a null range. If -- it cannot (because the value of Lo or Hi is not known at compile time) @@ -574,5 +581,6 @@ private pragma Inline (Eval_Unchecked_Conversion); pragma Inline (Is_OK_Static_Expression); + pragma Inline (Machine_Number); end Sem_Eval; -- 2.7.4