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Commit6253f9d

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In GCC-based builds, use a better newNode() macro that relies on GCC-specific
syntax to avoid a useless store into a global variable. Per experimentation,this works better than my original thought of trying to push the code intoan out-of-line subroutine.
1 parent7ad60b4 commit6253f9d

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2 files changed

+25
-2
lines changed

2 files changed

+25
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lines changed

‎src/backend/nodes/nodes.c

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@@ -9,7 +9,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/nodes/nodes.c,v 1.28 2008/01/01 19:45:50 momjian Exp $
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* $PostgreSQL: pgsql/src/backend/nodes/nodes.c,v 1.29 2008/08/29 22:49:07 tgl Exp $
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*
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* HISTORY
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* Andrew YuOct 20, 1994file creation
@@ -22,6 +22,10 @@
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/*
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* Support for newNode() macro
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*
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* In a GCC build there is no need for the global variable newNodeMacroHolder.
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* However, we create it anyway, to support the case of a non-GCC-built
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* loadable module being loaded into a GCC-built backend.
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*/
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Node*newNodeMacroHolder;

‎src/include/nodes/nodes.h

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@@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/nodes/nodes.h,v 1.209 2008/08/22 00:16:04 tgl Exp $
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* $PostgreSQL: pgsql/src/include/nodes/nodes.h,v 1.210 2008/08/29 22:49:07 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
@@ -384,6 +384,23 @@ typedef struct Node
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* !WARNING!: Avoid using newNode directly. You should be using the
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* macro makeNode. eg. to create a Query node, use makeNode(Query)
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*
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* Note: the size argument should always be a compile-time constant, so the
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* apparent risk of multiple evaluation doesn't matter in practice.
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*/
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#ifdef__GNUC__
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/* With GCC, we can use a compound statement within an expression */
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#definenewNode(size,tag) \
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({Node *_result; \
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AssertMacro((size) >= sizeof(Node));/* need the tag, at least */ \
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_result = (Node *) palloc0fast(size); \
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_result->type = (tag); \
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_result; \
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})
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#else
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/*
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*There is no way to dereference the palloc'ed pointer to assign the
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*tag, and also return the pointer itself, so we need a holder variable.
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*Fortunately, this macro isn't recursive so we just define
@@ -399,6 +416,8 @@ extern PGDLLIMPORT Node *newNodeMacroHolder;
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newNodeMacroHolder \
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)
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#endif/* __GNUC__ */
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#definemakeNode(_type_)((_type_ *) newNode(sizeof(_type_),T_##_type_))
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#defineNodeSetTag(nodeptr,t)(((Node*)(nodeptr))->type = (t))

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