diff options
Diffstat (limited to 'src/include/postgres.h')
| -rw-r--r-- | src/include/postgres.h | 79 |
1 files changed, 17 insertions, 62 deletions
diff --git a/src/include/postgres.h b/src/include/postgres.h index 8a41a668687..357cbd6fd96 100644 --- a/src/include/postgres.h +++ b/src/include/postgres.h @@ -58,15 +58,22 @@ /* * A Datum contains either a value of a pass-by-value type or a pointer to a - * value of a pass-by-reference type. Therefore, we require: - * - * sizeof(Datum) == sizeof(void *) == 4 or 8 + * value of a pass-by-reference type. Therefore, we must have + * sizeof(Datum) >= sizeof(void *). No current or foreseeable Postgres + * platform has pointers wider than 8 bytes, and standardizing on Datum being + * exactly 8 bytes has advantages in reducing cross-platform differences. * * The functions below and the analogous functions for other types should be used to * convert between a Datum and the appropriate C type. */ -typedef uintptr_t Datum; +typedef uint64_t Datum; + +/* + * This symbol is now vestigial, but we continue to define it so as not to + * unnecessarily break extension code. + */ +#define SIZEOF_DATUM 8 /* * A NullableDatum is used in places where both a Datum and its nullness needs @@ -83,8 +90,6 @@ typedef struct NullableDatum /* due to alignment padding this could be used for flags for free */ } NullableDatum; -#define SIZEOF_DATUM SIZEOF_VOID_P - /* * DatumGetBool * Returns boolean value of a datum. @@ -316,7 +321,7 @@ CommandIdGetDatum(CommandId X) static inline Pointer DatumGetPointer(Datum X) { - return (Pointer) X; + return (Pointer) (uintptr_t) X; } /* @@ -326,7 +331,7 @@ DatumGetPointer(Datum X) static inline Datum PointerGetDatum(const void *X) { - return (Datum) X; + return (Datum) (uintptr_t) X; } /* @@ -383,68 +388,41 @@ NameGetDatum(const NameData *X) /* * DatumGetInt64 * Returns 64-bit integer value of a datum. - * - * Note: this function hides whether int64 is pass by value or by reference. */ static inline int64 DatumGetInt64(Datum X) { -#ifdef USE_FLOAT8_BYVAL return (int64) X; -#else - return *((int64 *) DatumGetPointer(X)); -#endif } /* * Int64GetDatum * Returns datum representation for a 64-bit integer. - * - * Note: if int64 is pass by reference, this function returns a reference - * to palloc'd space. */ -#ifdef USE_FLOAT8_BYVAL static inline Datum Int64GetDatum(int64 X) { return (Datum) X; } -#else -extern Datum Int64GetDatum(int64 X); -#endif - /* * DatumGetUInt64 * Returns 64-bit unsigned integer value of a datum. - * - * Note: this function hides whether int64 is pass by value or by reference. */ static inline uint64 DatumGetUInt64(Datum X) { -#ifdef USE_FLOAT8_BYVAL return (uint64) X; -#else - return *((uint64 *) DatumGetPointer(X)); -#endif } /* * UInt64GetDatum * Returns datum representation for a 64-bit unsigned integer. - * - * Note: if int64 is pass by reference, this function returns a reference - * to palloc'd space. */ static inline Datum UInt64GetDatum(uint64 X) { -#ifdef USE_FLOAT8_BYVAL return (Datum) X; -#else - return Int64GetDatum((int64) X); -#endif } /* @@ -492,13 +470,10 @@ Float4GetDatum(float4 X) /* * DatumGetFloat8 * Returns 8-byte floating point value of a datum. - * - * Note: this function hides whether float8 is pass by value or by reference. */ static inline float8 DatumGetFloat8(Datum X) { -#ifdef USE_FLOAT8_BYVAL union { int64 value; @@ -507,19 +482,12 @@ DatumGetFloat8(Datum X) myunion.value = DatumGetInt64(X); return myunion.retval; -#else - return *((float8 *) DatumGetPointer(X)); -#endif } /* * Float8GetDatum * Returns datum representation for an 8-byte floating point number. - * - * Note: if float8 is pass by reference, this function returns a reference - * to palloc'd space. */ -#ifdef USE_FLOAT8_BYVAL static inline Datum Float8GetDatum(float8 X) { @@ -532,35 +500,22 @@ Float8GetDatum(float8 X) myunion.value = X; return Int64GetDatum(myunion.retval); } -#else -extern Datum Float8GetDatum(float8 X); -#endif - /* * Int64GetDatumFast * Float8GetDatumFast * - * These macros are intended to allow writing code that does not depend on + * These macros were intended to allow writing code that does not depend on * whether int64 and float8 are pass-by-reference types, while not - * sacrificing performance when they are. The argument must be a variable - * that will exist and have the same value for as long as the Datum is needed. - * In the pass-by-ref case, the address of the variable is taken to use as - * the Datum. In the pass-by-val case, these are the same as the non-Fast - * functions, except for asserting that the variable is of the correct type. + * sacrificing performance when they are. They are no longer different + * from the regular functions, though we keep the assertions to protect + * code that might get back-patched into older branches. */ -#ifdef USE_FLOAT8_BYVAL #define Int64GetDatumFast(X) \ (AssertVariableIsOfTypeMacro(X, int64), Int64GetDatum(X)) #define Float8GetDatumFast(X) \ (AssertVariableIsOfTypeMacro(X, double), Float8GetDatum(X)) -#else -#define Int64GetDatumFast(X) \ - (AssertVariableIsOfTypeMacro(X, int64), PointerGetDatum(&(X))) -#define Float8GetDatumFast(X) \ - (AssertVariableIsOfTypeMacro(X, double), PointerGetDatum(&(X))) -#endif /* ---------------------------------------------------------------- |