From 1586fadd37445cb5595867f3ed73c428dc2b7f68 Mon Sep 17 00:00:00 2001 From: Tristan Gingold Date: Thu, 7 Jul 2022 22:33:42 +0200 Subject: vhdl-evaluation: explicitly compute integer_exp to handle overflow. Tentatively fix crash on mingw32 --- src/vhdl/vhdl-evaluation.adb | 33 +++++++++++++++++++++++++++++++-- 1 file changed, 31 insertions(+), 2 deletions(-) (limited to 'src') diff --git a/src/vhdl/vhdl-evaluation.adb b/src/vhdl/vhdl-evaluation.adb index 653cbdb31..935f6e8ed 100644 --- a/src/vhdl/vhdl-evaluation.adb +++ b/src/vhdl/vhdl-evaluation.adb @@ -2167,8 +2167,37 @@ package body Vhdl.Evaluation is return Build_Overflow (Orig); end if; when Iir_Predefined_Integer_Exp => - return Build_Integer_Check - (Get_Value (Left) ** Integer (Get_Value (Right)), Orig); + declare + Exp : Int64; + Val : Int64; + Res : Int64; + begin + Val := Get_Value (Left); + -- LRM08 9.2.8 Misellaneous operators + -- Exponentiation with a negative exponent is only allowed for + -- a list operand of a floating-point type. + Exp := Get_Value (Right); + if Exp < 0 then + raise Constraint_Error; + end if; + -- LRM08 9.2.8 Misellaneous operators + -- Exponentiation with an integer exponent is equivalent to + -- repeated multiplication of the left operand by itself for + -- a number of times indicated by the absolute value of the + -- exponent and from left to right; [...] + -- GHDL: use the standard power-of-2 approach. This is not + -- strictly equivalent however. + Res := 1; + loop + if Exp mod 2 = 1 then + Res := Res * Val; + end if; + Exp := Exp / 2; + exit when Exp = 0; + Val := Val * Val; + end loop; + return Build_Integer_Check (Res, Orig); + end; when Iir_Predefined_Integer_Equality => return Build_Boolean (Get_Value (Left) = Get_Value (Right)); -- cgit v1.2.3