expression eval: Reduce number of steps for agg transition invocations.

Do so by combining the various steps that are part of aggregate
transition function invocation into one larger step. As some of the
current steps are only necessary for some aggregates, have one variant
of the aggregate transition step for each possible combination.

To avoid further manual copies of code in the different transition
step implementations, move most of the code into helper functions
marked as "always inline".

The benefit of this change is an increase in performance when
aggregating lots of rows. This comes in part due to the reduced number
of indirect jumps due to the reduced number of steps, and in part by
reducing redundant setup code across steps. This mainly benefits
interpreted execution, but the code generated by JIT is also improved
a bit.

As a nice side-effect it also ends up making the code a bit simpler.

A small additional optimization is removing the need to set
aggstate->curaggcontext before calling ExecAggInitGroup, choosing to
instead passign curaggcontext as an argument. It was, in contrast to
other aggregate related functions, only needed to fetch a memory
context to copy the transition value into.

Author: Andres Freund
Discussion:
   https://postgr.es/m/20191023163849.sosqbfs5yenocez3@alap3.anarazel.de
   https://postgr.es/m/5c371df7cee903e8cd4c685f90c6c72086d3a2dc.camel@j-davis.com

1 files changed, 83 insertions, 146 deletions

diff --git a/src/backend/jit/llvm/llvmjit_expr.c b/src/backend/jit/llvm/llvmjit_expr.c
index cea0d6fa5ce..dc16b399327 100644
--- a/src/backend/jit/llvm/llvmjit_expr.c
+++ b/src/backend/jit/llvm/llvmjit_expr.c
@@ -2046,152 +2046,12 @@ llvm_compile_expr(ExprState *state)
 					break;
 				}
 
-			case EEOP_AGG_INIT_TRANS:
-				{
-					AggStatePerTrans pertrans;
-
-					LLVMValueRef v_aggstatep;
-					LLVMValueRef v_pertransp;
-
-					LLVMValueRef v_allpergroupsp;
-
-					LLVMValueRef v_pergroupp;
-
-					LLVMValueRef v_setoff,
-								v_transno;
-
-					LLVMValueRef v_notransvalue;
-
-					LLVMBasicBlockRef b_init;
-
-					pertrans = op->d.agg_init_trans.pertrans;
-
-					v_aggstatep =
-						LLVMBuildBitCast(b, v_parent, l_ptr(StructAggState), "");
-					v_pertransp = l_ptr_const(pertrans,
-											  l_ptr(StructAggStatePerTransData));
-
-					/*
-					 * pergroup = &aggstate->all_pergroups
-					 * [op->d.agg_init_trans_check.setoff]
-					 * [op->d.agg_init_trans_check.transno];
-					 */
-					v_allpergroupsp =
-						l_load_struct_gep(b, v_aggstatep,
-										  FIELDNO_AGGSTATE_ALL_PERGROUPS,
-										  "aggstate.all_pergroups");
-					v_setoff = l_int32_const(op->d.agg_init_trans.setoff);
-					v_transno = l_int32_const(op->d.agg_init_trans.transno);
-					v_pergroupp =
-						LLVMBuildGEP(b,
-									 l_load_gep1(b, v_allpergroupsp, v_setoff, ""),
-									 &v_transno, 1, "");
-
-					v_notransvalue =
-						l_load_struct_gep(b, v_pergroupp,
-										  FIELDNO_AGGSTATEPERGROUPDATA_NOTRANSVALUE,
-										  "notransvalue");
-
-					b_init = l_bb_before_v(opblocks[opno + 1],
-										   "op.%d.inittrans", opno);
-
-					LLVMBuildCondBr(b,
-									LLVMBuildICmp(b, LLVMIntEQ, v_notransvalue,
-												  l_sbool_const(1), ""),
-									b_init,
-									opblocks[opno + 1]);
-
-					LLVMPositionBuilderAtEnd(b, b_init);
-
-					{
-						LLVMValueRef params[3];
-						LLVMValueRef v_curaggcontext;
-						LLVMValueRef v_current_set;
-						LLVMValueRef v_aggcontext;
-
-						v_aggcontext = l_ptr_const(op->d.agg_init_trans.aggcontext,
-												   l_ptr(StructExprContext));
-
-						v_current_set =
-							LLVMBuildStructGEP(b,
-											   v_aggstatep,
-											   FIELDNO_AGGSTATE_CURRENT_SET,
-											   "aggstate.current_set");
-						v_curaggcontext =
-							LLVMBuildStructGEP(b,
-											   v_aggstatep,
-											   FIELDNO_AGGSTATE_CURAGGCONTEXT,
-											   "aggstate.curaggcontext");
-
-						LLVMBuildStore(b, l_int32_const(op->d.agg_init_trans.setno),
-									   v_current_set);
-						LLVMBuildStore(b, v_aggcontext,
-									   v_curaggcontext);
-
-						params[0] = v_aggstatep;
-						params[1] = v_pertransp;
-						params[2] = v_pergroupp;
-
-						LLVMBuildCall(b,
-									  llvm_pg_func(mod, "ExecAggInitGroup"),
-									  params, lengthof(params),
-									  "");
-					}
-					LLVMBuildBr(b, opblocks[op->d.agg_init_trans.jumpnull]);
-
-					break;
-				}
-
-			case EEOP_AGG_STRICT_TRANS_CHECK:
-				{
-					LLVMValueRef v_setoff,
-								v_transno;
-
-					LLVMValueRef v_aggstatep;
-					LLVMValueRef v_allpergroupsp;
-
-					LLVMValueRef v_transnull;
-					LLVMValueRef v_pergroupp;
-
-					int			jumpnull = op->d.agg_strict_trans_check.jumpnull;
-
-					v_aggstatep =
-						LLVMBuildBitCast(b, v_parent, l_ptr(StructAggState), "");
-
-					/*
-					 * pergroup = &aggstate->all_pergroups
-					 * [op->d.agg_strict_trans_check.setoff]
-					 * [op->d.agg_init_trans_check.transno];
-					 */
-					v_allpergroupsp =
-						l_load_struct_gep(b, v_aggstatep,
-										  FIELDNO_AGGSTATE_ALL_PERGROUPS,
-										  "aggstate.all_pergroups");
-					v_setoff =
-						l_int32_const(op->d.agg_strict_trans_check.setoff);
-					v_transno =
-						l_int32_const(op->d.agg_strict_trans_check.transno);
-					v_pergroupp =
-						LLVMBuildGEP(b,
-									 l_load_gep1(b, v_allpergroupsp, v_setoff, ""),
-									 &v_transno, 1, "");
-
-					v_transnull =
-						l_load_struct_gep(b, v_pergroupp,
-										  FIELDNO_AGGSTATEPERGROUPDATA_TRANSVALUEISNULL,
-										  "transnull");
-
-					LLVMBuildCondBr(b,
-									LLVMBuildICmp(b, LLVMIntEQ, v_transnull,
-												  l_sbool_const(1), ""),
-									opblocks[jumpnull],
-									opblocks[opno + 1]);
-
-					break;
-				}
-
+			case EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYVAL:
+			case EEOP_AGG_PLAIN_TRANS_STRICT_BYVAL:
 			case EEOP_AGG_PLAIN_TRANS_BYVAL:
-			case EEOP_AGG_PLAIN_TRANS:
+			case EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYREF:
+			case EEOP_AGG_PLAIN_TRANS_STRICT_BYREF:
+			case EEOP_AGG_PLAIN_TRANS_BYREF:
 				{
 					AggState   *aggstate;
 					AggStatePerTrans pertrans;
@@ -2249,6 +2109,81 @@ llvm_compile_expr(ExprState *state)
 									 l_load_gep1(b, v_allpergroupsp, v_setoff, ""),
 									 &v_transno, 1, "");
 
+
+					if (opcode == EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYVAL ||
+						opcode == EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYREF)
+					{
+						LLVMValueRef v_notransvalue;
+						LLVMBasicBlockRef b_init;
+						LLVMBasicBlockRef b_no_init;
+
+						v_notransvalue =
+							l_load_struct_gep(b, v_pergroupp,
+											  FIELDNO_AGGSTATEPERGROUPDATA_NOTRANSVALUE,
+											  "notransvalue");
+
+						b_init = l_bb_before_v(opblocks[opno + 1],
+											   "op.%d.inittrans", opno);
+						b_no_init = l_bb_before_v(opblocks[opno + 1],
+												  "op.%d.no_inittrans", opno);
+
+						LLVMBuildCondBr(b,
+										LLVMBuildICmp(b, LLVMIntEQ, v_notransvalue,
+													  l_sbool_const(1), ""),
+										b_init,
+										b_no_init);
+
+						/* block to init the transition value if necessary */
+						{
+							LLVMValueRef params[4];
+
+							LLVMPositionBuilderAtEnd(b, b_init);
+
+							v_aggcontext = l_ptr_const(op->d.agg_trans.aggcontext,
+													   l_ptr(StructExprContext));
+
+							params[0] = v_aggstatep;
+							params[1] = v_pertransp;
+							params[2] = v_pergroupp;
+							params[3] = v_aggcontext;
+
+							LLVMBuildCall(b,
+										  llvm_pg_func(mod, "ExecAggInitGroup"),
+										  params, lengthof(params),
+										  "");
+
+							LLVMBuildBr(b, opblocks[opno + 1]);
+
+						}
+
+						LLVMPositionBuilderAtEnd(b, b_no_init);
+					}
+
+					if (opcode == EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYVAL ||
+						opcode == EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYREF ||
+						opcode == EEOP_AGG_PLAIN_TRANS_STRICT_BYVAL ||
+						opcode == EEOP_AGG_PLAIN_TRANS_STRICT_BYREF)
+					{
+						LLVMValueRef v_transnull;
+						LLVMBasicBlockRef b_strictpass;
+
+						b_strictpass = l_bb_before_v(opblocks[opno + 1],
+													 "op.%d.strictpass", opno);
+						v_transnull =
+							l_load_struct_gep(b, v_pergroupp,
+											  FIELDNO_AGGSTATEPERGROUPDATA_TRANSVALUEISNULL,
+											  "transnull");
+
+						LLVMBuildCondBr(b,
+										LLVMBuildICmp(b, LLVMIntEQ, v_transnull,
+													  l_sbool_const(1), ""),
+										opblocks[opno + 1],
+										b_strictpass);
+
+						LLVMPositionBuilderAtEnd(b, b_strictpass);
+					}
+
+
 					v_fcinfo = l_ptr_const(fcinfo,
 										   l_ptr(StructFunctionCallInfoData));
 					v_aggcontext = l_ptr_const(op->d.agg_trans.aggcontext,
@@ -2312,7 +2247,9 @@ llvm_compile_expr(ExprState *state)
 					 * child of the aggcontext, assume we can adopt that value
 					 * without copying it.
 					 */
-					if (opcode == EEOP_AGG_PLAIN_TRANS)
+					if (opcode == EEOP_AGG_PLAIN_TRANS_INIT_STRICT_BYREF ||
+						opcode == EEOP_AGG_PLAIN_TRANS_STRICT_BYREF ||
+						opcode == EEOP_AGG_PLAIN_TRANS_BYREF)
 					{
 						LLVMBasicBlockRef b_call;
 						LLVMBasicBlockRef b_nocall;