変数に格納された符号付き整数の算術ビット単位の右シフト「a shr b」 – 間違った結果! Delphi の内部バグ? 質問する

0-2-3 の場合に奇妙な「9223372036854775807」(覚えていない「-1」、「Integer(-1)」、「Integer($FFFFFFFF)」がありました)。

以下は Delphi での私の例全体です。

program bug;

{$APPTYPE CONSOLE}

// Simple shift right with signed integers
function shrI(a,b:Integer):Integer;
begin
Result := a shr b;
end;

// Simple shift right with unsigned integers
function shrC(a,b:Cardinal):Cardinal;
begin
Result := a shr b;
end;

// Logical shift right with signed integers
function srlI(a,b:Integer):Integer;
begin
Result := (a shr b) and ((1 shl (32-b))-1);
end;

// Arithmetic shift right with signed integers
function sraI(a,b:Integer):Integer;
begin
Result := (a shr b) or (( 0-((a shr 31) and 1)) shl (32-b));
end;

// Logical shift right with unsigned integers
function srlC(a,b:Cardinal):Cardinal;
begin
Result := (a shr b) and ((1 shl (32-b))-1);
end;

// Arithmetic shift right with unsigned integers
function sraC(a,b:Cardinal):Cardinal;
begin
Result := (a shr b) or (( 0-((a shr 31) and 1)) shl (32-b));
end;

var
I:Integer;
C:Cardinal;

begin
I := -1;
C := $FFFFFFFF;

Writeln('0) ', -1 shr 1 );
Writeln('1) ', $FFFFFFFF shr 1 );
// 0) -1           - correct
// 1) 2147483647   - correct

Writeln('2) ', Integer(-1) shr 1 );
Writeln('3) ', Integer($FFFFFFFF) shr 1 );
// 2) -1           - correct
// 3) -1           - correct

Writeln('4) ', Cardinal(-1) shr 1 );
Writeln('5) ', Cardinal($FFFFFFFF) shr 1 );
// 4) 2147483647   - correct
// 5) 2147483647   - correct

Writeln('6) ', I shr 1 );
Writeln('7) ', C shr 1 );
// 6) 2147483647   - INCORRECT!
// 7) 2147483647   - correct

Writeln('8) ', Integer(I) shr 1 );
Writeln('9) ', Cardinal(I) shr 1 );
// 8) 2147483647   - INCORRECT!
// 9) 2147483647   - correct

Writeln('A) ', Integer(C) shr 1 );
Writeln('B) ', Cardinal(C) shr 1 );
// A) 2147483647   - INCORRECT!
// B) 2147483647   - correct

Writeln('C) ', shrI(-1,1) );
Writeln('D) ', shrC($FFFFFFFF,1) );
// C) 2147483647   - INCORRECT!
// D) 2147483647   - correct

Writeln('E) ', sraI(-1,1) );
Writeln('F) ', srlI(-1,1) );
// E) -1           - correct
// F) 2147483647   - correct

Writeln('G) ', sraC($FFFFFFFF,1) );
Writeln('H) ', srlC($FFFFFFFF,1) );
// G) 4294967295   - correct
// H) 2147483647   - correct

Writeln('K) ', sraI(I,1) );
Writeln('L) ', srlI(I,1) );
// K) -1           - correct
// L) 2147483647   - correct

Writeln('M) ', sraC(C,1) );
Writeln('N) ', srlC(C,1) );
// M) 4294967295   - correct
// N) 2147483647   - correct

end.

0) -1
1) 2147483647
2) -1
3) -1
4) 2147483647
5) 2147483647
6) -1
7) 2147483647
8) -1
9) 2147483647
A) -1
B) 2147483647
C) -1
D) 2147483647
E) -1
F) 2147483647
G) 4294967295
H) 2147483647
K) -1
L) 2147483647
M) 4294967295
N) 2147483647

#include <iostream>
using namespace std;

// Simple shift right with signed integers
int shrI(int a, int b){
return a >> b;
}

// Simple shift right with unsigned integers
unsigned int shrC(unsigned int a, unsigned int b){
return a >> b;
}

// Logical shift right with signed integers
int srlI(int a, int b){
return (a >> b) & ((1 << (32-b))-1);
}

// Arithmetic shift right with signed integers
int sraI(int a, int b){
return (a >> b) | (( 0-((a >> 31) & 1)) << (32-b));
}

// Logical shift right with unsigned integers
unsigned int srlC(unsigned int a, unsigned int b){
return (a >> b) & ((1 << (32-b))-1);
}

// Arithmetic shift right with unsigned integers
unsigned int sraC(unsigned int a, unsigned int b){
return (a >> b) | (( 0-((a >> 31) & 1)) << (32-b));
}

int I;
unsigned int C;

int main(){
I = -1;
C = 0xFFFFFFFF;

cout<<"0) "<<( -1 >> 1 )<<endl;
cout<<"1) "<<( 0xFFFFFFFF >> 1 )<<endl;
// 0) -1           - correct
// 1) 2147483647   - correct

cout<<"2) "<<( ((int)(-1)) >> 1 )<<endl;
cout<<"3) "<<( ((int)(0xFFFFFFFF)) >> 1 )<<endl;
// 2) -1           - correct
// 3) -1           - correct

cout<<"4) "<<( ((unsigned int)(-1)) >> 1 )<<endl;
cout<<"5) "<<( ((unsigned int)(0xFFFFFFFF)) >> 1 )<<endl;
// 4) 2147483647   - correct
// 5) 2147483647   - correct

cout<<"6) "<<( I >> 1 )<<endl;
cout<<"7) "<<( C >> 1 )<<endl;
// 6) -1           - correct
// 7) 2147483647   - correct

cout<<"8) "<<( ((int)(I)) >> 1 )<<endl;
cout<<"9) "<<( ((unsigned int)(I)) >> 1 )<<endl;
// 8) -1           - correct
// 9) 2147483647   - correct

cout<<"A) "<<( ((int)(C)) >> 1 )<<endl;
cout<<"B) "<<( ((unsigned int)(C)) >> 1 )<<endl;
// A) -1           - correct
// B) 2147483647   - correct

cout<<"C) "<<( shrI(-1,1) )<<endl;
cout<<"D) "<<( shrC(0xFFFFFFFF,1) )<<endl;
// C) -1           - correct
// D) 2147483647   - correct

cout<<"E) "<<( sraI(-1,1) )<<endl;
cout<<"F) "<<( srlI(-1,1) )<<endl;
// E) -1           - correct
// F) 2147483647   - correct

cout<<"G) "<<( sraC(0xFFFFFFFF,1) )<<endl;
cout<<"H) "<<( srlC(0xFFFFFFFF,1) )<<endl;
// G) 4294967295   - correct
// H) 2147483647   - correct

cout<<"K) "<<( sraI(I,1) )<<endl;
cout<<"L) "<<( srlI(I,1) )<<endl;
// K) -1           - correct
// L) 2147483647   - correct

cout<<"M) "<<( sraC(C,1) )<<endl;
cout<<"N) "<<( srlC(C,1) )<<endl;
// M) 4294967295   - correct
// N) 2147483647   - correct

}