From 8a1878a57acaea4cbe7023c922ccbc31828cc7e5 Mon Sep 17 00:00:00 2001
From: Jordan Lewis <jordanthelewis@gmail.com>
Date: Mon, 9 Sep 2019 01:05:42 -0400
Subject: [PATCH] exec: don't template asc vs desc in mj

This saves 7mb of generated code for 2-3% slowdown.

Release note: None
---
 .../execgen/cmd/execgen/mergejoiner_gen.go    |  5 ++-
 pkg/sql/exec/mergejoiner_tmpl.go              | 31 ++++---------------
 2 files changed, 8 insertions(+), 28 deletions(-)

diff --git a/pkg/sql/exec/execgen/cmd/execgen/mergejoiner_gen.go b/pkg/sql/exec/execgen/cmd/execgen/mergejoiner_gen.go
index 1dd370fc47fa..772b8eba425e 100644
--- a/pkg/sql/exec/execgen/cmd/execgen/mergejoiner_gen.go
+++ b/pkg/sql/exec/execgen/cmd/execgen/mergejoiner_gen.go
@@ -88,7 +88,6 @@ func genMergeJoinOps(wr io.Writer, jti joinTypeInfo) error {
 	s = strings.Replace(s, "_HAS_NULLS", "$.HasNulls", -1)
 	s = strings.Replace(s, "_HAS_SELECTION", "$.HasSelection", -1)
 	s = strings.Replace(s, "_SEL_PERMUTATION", "$.SelPermutation", -1)
-	s = strings.Replace(s, "_ASC_DIRECTION", "$.AscDirection", -1)
 
 	leftUnmatchedGroupSwitch := makeFunctionRegex("_LEFT_UNMATCHED_GROUP_SWITCH", 1)
 	s = leftUnmatchedGroupSwitch.ReplaceAllString(s, `{{template "leftUnmatchedGroupSwitch" buildDict "Global" $ "JoinType" $1}}`)
@@ -111,8 +110,8 @@ func genMergeJoinOps(wr io.Writer, jti joinTypeInfo) error {
 	processNotLastGroupInColumnSwitch := makeFunctionRegex("_PROCESS_NOT_LAST_GROUP_IN_COLUMN_SWITCH", 1)
 	s = processNotLastGroupInColumnSwitch.ReplaceAllString(s, `{{template "processNotLastGroupInColumnSwitch" buildDict "Global" $ "JoinType" $1}}`)
 
-	probeSwitch := makeFunctionRegex("_PROBE_SWITCH", 6)
-	s = probeSwitch.ReplaceAllString(s, `{{template "probeSwitch" buildDict "Global" $ "JoinType" $1 "FilterInfo" $2 "SelPermutation" $3 "lHasNulls" $4 "rHasNulls" $5 "AscDirection" $6}}`)
+	probeSwitch := makeFunctionRegex("_PROBE_SWITCH", 5)
+	s = probeSwitch.ReplaceAllString(s, `{{template "probeSwitch" buildDict "Global" $ "JoinType" $1 "FilterInfo" $2 "SelPermutation" $3 "lHasNulls" $4 "rHasNulls" $5}}`)
 
 	sourceFinishedSwitch := makeFunctionRegex("_SOURCE_FINISHED_SWITCH", 1)
 	s = sourceFinishedSwitch.ReplaceAllString(s, `{{template "sourceFinishedSwitch" buildDict "Global" $ "JoinType" $1}}`)
diff --git a/pkg/sql/exec/mergejoiner_tmpl.go b/pkg/sql/exec/mergejoiner_tmpl.go
index 8e4981f99927..023d652b5e89 100644
--- a/pkg/sql/exec/mergejoiner_tmpl.go
+++ b/pkg/sql/exec/mergejoiner_tmpl.go
@@ -121,7 +121,6 @@ func _PROBE_SWITCH(
 	_SEL_PERMUTATION selPermutation,
 	_L_HAS_NULLS bool,
 	_R_HAS_NULLS bool,
-	_ASC_DIRECTION bool,
 ) { // */}}
 	// {{define "probeSwitch"}}
 	// {{ $sel := $.SelPermutation }}
@@ -270,11 +269,9 @@ func _PROBE_SWITCH(
 					}
 				} else { // mismatch
 					var incrementLeft bool
-					// {{ if _ASC_DIRECTION }}
 					_ASSIGN_LT("incrementLeft", "lVal", "rVal")
-					// {{ else }}
-					_ASSIGN_GT("incrementLeft", "lVal", "rVal")
-					// {{ end }}
+					// Switch the direction of increment if we're sorted descendingly.
+					incrementLeft = incrementLeft == (o.left.directions[eqColIdx] == distsqlpb.Ordering_Column_ASC)
 					if incrementLeft {
 						curLIdx++
 						// {{ if _L_HAS_NULLS }}
@@ -588,31 +585,15 @@ EqLoop:
 		colType := o.left.sourceTypes[int(o.left.eqCols[eqColIdx])]
 		if lVec.MaybeHasNulls() {
 			if rVec.MaybeHasNulls() {
-				if o.left.directions[eqColIdx] == distsqlpb.Ordering_Column_ASC {
-					_PROBE_SWITCH(_JOIN_TYPE, _FILTER_INFO, _SEL_ARG, true, true, true)
-				} else {
-					_PROBE_SWITCH(_JOIN_TYPE, _FILTER_INFO, _SEL_ARG, true, true, false)
-				}
+				_PROBE_SWITCH(_JOIN_TYPE, _FILTER_INFO, _SEL_ARG, true, true)
 			} else {
-				if o.left.directions[eqColIdx] == distsqlpb.Ordering_Column_ASC {
-					_PROBE_SWITCH(_JOIN_TYPE, _FILTER_INFO, _SEL_ARG, true, false, true)
-				} else {
-					_PROBE_SWITCH(_JOIN_TYPE, _FILTER_INFO, _SEL_ARG, true, false, false)
-				}
+				_PROBE_SWITCH(_JOIN_TYPE, _FILTER_INFO, _SEL_ARG, true, false)
 			}
 		} else {
 			if rVec.MaybeHasNulls() {
-				if o.left.directions[eqColIdx] == distsqlpb.Ordering_Column_ASC {
-					_PROBE_SWITCH(_JOIN_TYPE, _FILTER_INFO, _SEL_ARG, false, true, true)
-				} else {
-					_PROBE_SWITCH(_JOIN_TYPE, _FILTER_INFO, _SEL_ARG, false, true, false)
-				}
+				_PROBE_SWITCH(_JOIN_TYPE, _FILTER_INFO, _SEL_ARG, false, true)
 			} else {
-				if o.left.directions[eqColIdx] == distsqlpb.Ordering_Column_ASC {
-					_PROBE_SWITCH(_JOIN_TYPE, _FILTER_INFO, _SEL_ARG, false, false, true)
-				} else {
-					_PROBE_SWITCH(_JOIN_TYPE, _FILTER_INFO, _SEL_ARG, false, false, false)
-				}
+				_PROBE_SWITCH(_JOIN_TYPE, _FILTER_INFO, _SEL_ARG, false, false)
 			}
 		}
 		// Look at the groups associated with the next equality column by moving