From 14a226107f845454676a2e14ae0fb843a5b4f668 Mon Sep 17 00:00:00 2001
From: Pierre Ducroquet <p.psql@pinaraf.info>
Date: Wed, 11 Jul 2018 23:41:59 +0200
Subject: [PATCH 1/2] Check for the hasnulls attribute before checking
 individual fields

---
 src/backend/jit/llvm/llvmjit_deform.c | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/src/backend/jit/llvm/llvmjit_deform.c b/src/backend/jit/llvm/llvmjit_deform.c
index 795f67114e..c53855eb63 100644
--- a/src/backend/jit/llvm/llvmjit_deform.c
+++ b/src/backend/jit/llvm/llvmjit_deform.c
@@ -48,6 +48,7 @@ slot_compile_deform(LLVMJitContext *context, TupleDesc desc, int natts)
 	LLVMBasicBlockRef b_out;
 	LLVMBasicBlockRef b_dead;
 	LLVMBasicBlockRef *attcheckattnoblocks;
+	LLVMBasicBlockRef *attfaststartblocks;
 	LLVMBasicBlockRef *attstartblocks;
 	LLVMBasicBlockRef *attisnullblocks;
 	LLVMBasicBlockRef *attcheckalignblocks;
@@ -145,6 +146,7 @@ slot_compile_deform(LLVMJitContext *context, TupleDesc desc, int natts)
 	b = LLVMCreateBuilder();
 
 	attcheckattnoblocks = palloc(sizeof(LLVMBasicBlockRef) * natts);
+	attfaststartblocks = palloc(sizeof(LLVMBasicBlockRef) * natts);
 	attstartblocks = palloc(sizeof(LLVMBasicBlockRef) * natts);
 	attisnullblocks = palloc(sizeof(LLVMBasicBlockRef) * natts);
 	attcheckalignblocks = palloc(sizeof(LLVMBasicBlockRef) * natts);
@@ -239,6 +241,8 @@ slot_compile_deform(LLVMJitContext *context, TupleDesc desc, int natts)
 	{
 		attcheckattnoblocks[attnum] =
 			l_bb_append_v(v_deform_fn, "block.attr.%d.attcheckattno", attnum);
+		attfaststartblocks[attnum] =
+			l_bb_append_v(v_deform_fn, "block.attr.%d.faststart", attnum);
 		attstartblocks[attnum] =
 			l_bb_append_v(v_deform_fn, "block.attr.%d.start", attnum);
 		attisnullblocks[attnum] =
@@ -337,7 +341,7 @@ slot_compile_deform(LLVMJitContext *context, TupleDesc desc, int natts)
 
 		/*
 		 * If this is the first attribute, slot->tts_nvalid was 0. Therefore
-		 * reset offset to 0 to, it be from a previous execution.
+		 * reset offset to 0 too, it could be from a previous execution.
 		 */
 		if (attnum == 0)
 		{
@@ -351,7 +355,7 @@ slot_compile_deform(LLVMJitContext *context, TupleDesc desc, int natts)
 		 */
 		if (attnum <= guaranteed_column_number)
 		{
-			LLVMBuildBr(b, attstartblocks[attnum]);
+			LLVMBuildBr(b, attfaststartblocks[attnum]);
 		}
 		else
 		{
@@ -361,8 +365,19 @@ slot_compile_deform(LLVMJitContext *context, TupleDesc desc, int natts)
 									 l_attno,
 									 v_maxatt,
 									 "heap_natts");
-			LLVMBuildCondBr(b, v_islast, b_out, attstartblocks[attnum]);
+			LLVMBuildCondBr(b, v_islast, b_out, attfaststartblocks[attnum]);
 		}
+
+		LLVMPositionBuilderAtEnd(b, attfaststartblocks[attnum]);
+
+		/*
+		 * Fast-start block : check if there can be nulls on tuple.
+		 * If not, jump straight to align checks.
+		 */
+		{
+			LLVMBuildCondBr(b, v_hasnulls, attstartblocks[attnum], attcheckalignblocks[attnum]);
+		}
+
 		LLVMPositionBuilderAtEnd(b, attstartblocks[attnum]);
 
 		/*
@@ -375,7 +390,6 @@ slot_compile_deform(LLVMJitContext *context, TupleDesc desc, int natts)
 			LLVMBasicBlockRef b_ifnotnull;
 			LLVMBasicBlockRef b_ifnull;
 			LLVMBasicBlockRef b_next;
-			LLVMValueRef v_attisnull;
 			LLVMValueRef v_nullbyteno;
 			LLVMValueRef v_nullbytemask;
 			LLVMValueRef v_nullbyte;
@@ -399,9 +413,7 @@ slot_compile_deform(LLVMJitContext *context, TupleDesc desc, int natts)
 									  l_int8_const(0),
 									  "attisnull");
 
-			v_attisnull = LLVMBuildAnd(b, v_hasnulls, v_nullbit, "");
-
-			LLVMBuildCondBr(b, v_attisnull, b_ifnull, b_ifnotnull);
+			LLVMBuildCondBr(b, v_nullbit, b_ifnull, b_ifnotnull);
 
 			LLVMPositionBuilderAtEnd(b, b_ifnull);
 
-- 
2.18.0