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Simplify newNode() by removing special cases

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- Remove MemoryContextAllocZeroAligned(). It was supposed to be a
  faster version of MemoryContextAllocZero(), but modern compilers turn
  the MemSetLoop() into a call to memset() anyway, making it more or
  less identical to MemoryContextAllocZero(). That was the only user of
  MemSetTest, MemSetLoop, so remove those too, as well as palloc0fast().

- Convert newNode() to a static inline function. When this was
  originally originally written, it was written as a macro because
  testing showed that gcc didn't inline the size check as we
  intended. Modern compiler versions do, and now that it just calls
  palloc0() there is no size-check to inline anyway.

One nice effect is that the palloc0() takes one less argument than
MemoryContextAllocZeroAligned(), which saves a few instructions in the
callers of newNode().

Reviewed-by: Peter Eisentraut, Tom Lane, John Naylor, Thomas Munro
Discussion: https://www.postgresql.org/message-id/b51f1fa7-7e6a-4ecc-936d-90a8a1659e7c@iki.fi
This commit is contained in:
Heikki Linnakangas
2023-12-19 12:11:47 +02:00
parent 2084701364
commit 3c080fb4fa
7 changed files with 9 additions and 139 deletions
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14
src/include/utils/palloc.h
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@@ -70,7 +70,6 @@ extern PGDLLIMPORT MemoryContext CurrentMemoryContext;
*/
extern void *MemoryContextAlloc(MemoryContext context, Size size);
extern void *MemoryContextAllocZero(MemoryContext context, Size size);
extern void *MemoryContextAllocZeroAligned(MemoryContext context, Size size);
extern void *MemoryContextAllocExtended(MemoryContext context,
Size size, int flags);
extern void *MemoryContextAllocAligned(MemoryContext context,
@@ -109,19 +108,6 @@ extern void pfree(void *pointer);
#define repalloc_array(pointer, type, count) ((type *) repalloc(pointer, sizeof(type) * (count)))
#define repalloc0_array(pointer, type, oldcount, count) ((type *) repalloc0(pointer, sizeof(type) * (oldcount), sizeof(type) * (count)))
/*
* The result of palloc() is always word-aligned, so we can skip testing
* alignment of the pointer when deciding which MemSet variant to use.
* Note that this variant does not offer any advantage, and should not be
* used, unless its "sz" argument is a compile-time constant; therefore, the
* issue that it evaluates the argument multiple times isn't a problem in
* practice.
*/
#define palloc0fast(sz) \
( MemSetTest(0, sz) ? \
MemoryContextAllocZeroAligned(CurrentMemoryContext, sz) : \
MemoryContextAllocZero(CurrentMemoryContext, sz) )
/* Higher-limit allocators. */
extern void *MemoryContextAllocHuge(MemoryContext context, Size size);
extern pg_nodiscard void *repalloc_huge(void *pointer, Size size);