open-dsi
/
postgres
mirror of https://github.com/postgres/postgres
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Marginal improvement for generated code in execExprInterp.c.

Browse Source 
Avoid the coding pattern "*op->resvalue = f();", as some compilers think
that requires them to evaluate "op->resvalue" before the function call.
Unless there are lots of free registers, this can lead to a useless
register spill and reload across the call.

I changed all the cases like this in ExecInterpExpr(), but didn't bother
in the out-of-line opcode eval subroutines, since those are presumably
not as performance-critical.

Discussion: https://postgr.es/m/2508.1506630094@sss.pgh.pa.us
pull/31/head^2
Tom Lane 8 years ago
parent 5373bc2a08
commit 136ab7c5a5
1 changed files with 42 additions and 17 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Show Stats Download Patch File Download Diff File
  1. 59
      src/backend/executor/execExprInterp.c

59
src/backend/executor/execExprInterp.c
Unescape View File

@ -501,15 +501,17 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
EEO_CASE(EEOP_INNER_SYSVAR)
{
int attnum = op->d.var.attnum;
Datum d;
/* these asserts must match defenses in slot_getattr */
Assert(innerslot->tts_tuple != NULL);
Assert(innerslot->tts_tuple != &(innerslot->tts_minhdr));
/* heap_getsysattr has sufficient defenses against bad attnums */
*op->resvalue = heap_getsysattr(innerslot->tts_tuple, attnum,
innerslot->tts_tupleDescriptor,
op->resnull);
/* heap_getsysattr has sufficient defenses against bad attnums */
d = heap_getsysattr(innerslot->tts_tuple, attnum,
innerslot->tts_tupleDescriptor,
op->resnull);
*op->resvalue = d;
EEO_NEXT();
}
@ -517,15 +519,17 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
EEO_CASE(EEOP_OUTER_SYSVAR)
{
int attnum = op->d.var.attnum;
Datum d;
/* these asserts must match defenses in slot_getattr */
Assert(outerslot->tts_tuple != NULL);
Assert(outerslot->tts_tuple != &(outerslot->tts_minhdr));
/* heap_getsysattr has sufficient defenses against bad attnums */
*op->resvalue = heap_getsysattr(outerslot->tts_tuple, attnum,
outerslot->tts_tupleDescriptor,
op->resnull);
d = heap_getsysattr(outerslot->tts_tuple, attnum,
outerslot->tts_tupleDescriptor,
op->resnull);
*op->resvalue = d;
EEO_NEXT();
}
@ -533,15 +537,17 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
EEO_CASE(EEOP_SCAN_SYSVAR)
{
int attnum = op->d.var.attnum;
Datum d;
/* these asserts must match defenses in slot_getattr */
Assert(scanslot->tts_tuple != NULL);
Assert(scanslot->tts_tuple != &(scanslot->tts_minhdr));
/* heap_getsysattr has sufficient defenses against bad attnums */
*op->resvalue = heap_getsysattr(scanslot->tts_tuple, attnum,
scanslot->tts_tupleDescriptor,
op->resnull);
/* heap_getsysattr has sufficient defenses against bad attnums */
d = heap_getsysattr(scanslot->tts_tuple, attnum,
scanslot->tts_tupleDescriptor,
op->resnull);
*op->resvalue = d;
EEO_NEXT();
}
@ -641,13 +647,22 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
* As both STRICT checks and function-usage are noticeable performance
* wise, and function calls are a very hot-path (they also back
* operators!), it's worth having so many separate opcodes.
*
* Note: the reason for using a temporary variable "d", here and in
* other places, is that some compilers think "*op->resvalue = f();"
* requires them to evaluate op->resvalue into a register before
* calling f(), just in case f() is able to modify op->resvalue
* somehow. The extra line of code can save a useless register spill
* and reload across the function call.
*/
EEO_CASE(EEOP_FUNCEXPR)
{
FunctionCallInfo fcinfo = op->d.func.fcinfo_data;
Datum d;
fcinfo->isnull = false;
*op->resvalue = op->d.func.fn_addr(fcinfo);
d = op->d.func.fn_addr(fcinfo);
*op->resvalue = d;
*op->resnull = fcinfo->isnull;
EEO_NEXT();
@ -658,6 +673,7 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
FunctionCallInfo fcinfo = op->d.func.fcinfo_data;
bool *argnull = fcinfo->argnull;
int argno;
Datum d;
/* strict function, so check for NULL args */
for (argno = 0; argno < op->d.func.nargs; argno++)
@ -669,7 +685,8 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
}
}
fcinfo->isnull = false;
*op->resvalue = op->d.func.fn_addr(fcinfo);
d = op->d.func.fn_addr(fcinfo);
*op->resvalue = d;
*op->resnull = fcinfo->isnull;
strictfail:
@ -680,11 +697,13 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
{
FunctionCallInfo fcinfo = op->d.func.fcinfo_data;
PgStat_FunctionCallUsage fcusage;
Datum d;
pgstat_init_function_usage(fcinfo, &fcusage);
fcinfo->isnull = false;
*op->resvalue = op->d.func.fn_addr(fcinfo);
d = op->d.func.fn_addr(fcinfo);
*op->resvalue = d;
*op->resnull = fcinfo->isnull;
pgstat_end_function_usage(&fcusage, true);
@ -698,6 +717,7 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
PgStat_FunctionCallUsage fcusage;
bool *argnull = fcinfo->argnull;
int argno;
Datum d;
/* strict function, so check for NULL args */
for (argno = 0; argno < op->d.func.nargs; argno++)
@ -712,7 +732,8 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
pgstat_init_function_usage(fcinfo, &fcusage);
fcinfo->isnull = false;
*op->resvalue = op->d.func.fn_addr(fcinfo);
d = op->d.func.fn_addr(fcinfo);
*op->resvalue = d;
*op->resnull = fcinfo->isnull;
pgstat_end_function_usage(&fcusage, true);
@ -1113,6 +1134,7 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
if (!op->d.iocoerce.finfo_in->fn_strict || str != NULL)
{
FunctionCallInfo fcinfo_in;
Datum d;
fcinfo_in = op->d.iocoerce.fcinfo_data_in;
fcinfo_in->arg[0] = PointerGetDatum(str);
@ -1120,7 +1142,8 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
/* second and third arguments are already set up */
fcinfo_in->isnull = false;
*op->resvalue = FunctionCallInvoke(fcinfo_in);
d = FunctionCallInvoke(fcinfo_in);
*op->resvalue = d;
/* Should get null result if and only if str is NULL */
if (str == NULL)
@ -1268,6 +1291,7 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
EEO_CASE(EEOP_ROWCOMPARE_STEP)
{
FunctionCallInfo fcinfo = op->d.rowcompare_step.fcinfo_data;
Datum d;
/* force NULL result if strict fn and NULL input */
if (op->d.rowcompare_step.finfo->fn_strict &&
@ -1279,7 +1303,8 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
/* Apply comparison function */
fcinfo->isnull = false;
*op->resvalue = op->d.rowcompare_step.fn_addr(fcinfo);
d = op->d.rowcompare_step.fn_addr(fcinfo);
*op->resvalue = d;
/* force NULL result if NULL function result */
if (fcinfo->isnull)

Write Preview
Loading…
Cancel
Save