From d025cf88ba5a64487ee4a17ef23e8f55b1536606 Mon Sep 17 00:00:00 2001
From: David Rowley
Date: Wed, 8 Apr 2020 16:55:03 +1200
Subject: Modify various power 2 calculations to use new helper functions

First pass of modifying various places that obtain the next power of 2 of
a number and make them use the new functions added in pg_bitutils.h
instead.

This also removes the _hash_log2() function. There are no longer any
callers in core. Other users can swap their _hash_log2(n) call to make use
of pg_ceil_log2_32(n).

Author: David Fetter, with some minor adjustments by me
Reviewed-by: John Naylor, Jesse Zhang
Discussion: https://postgr.es/m/20200114173553.GE32763%40fetter.org
---
 src/include/lib/simplehash.h | 27 ++++-----------------------
 1 file changed, 4 insertions(+), 23 deletions(-)

(limited to 'src/include/lib')

diff --git a/src/include/lib/simplehash.h b/src/include/lib/simplehash.h
index 5a6783f653..8cb03cda6c 100644
--- a/src/include/lib/simplehash.h
+++ b/src/include/lib/simplehash.h
@@ -57,6 +57,8 @@
  *	  backwards, unless they're empty or already at their optimal position.
  */
 
+#include "port/pg_bitutils.h"
+
 /* helpers */
 #define SH_MAKE_PREFIX(a) CppConcat(a,_)
 #define SH_MAKE_NAME(name) SH_MAKE_NAME_(SH_MAKE_PREFIX(SH_PREFIX),name)
@@ -215,27 +217,6 @@ SH_SCOPE void SH_STAT(SH_TYPE * tb);
 #ifndef SIMPLEHASH_H
 #define SIMPLEHASH_H
 
-/* FIXME: can we move these to a central location? */
-
-/* calculate ceil(log base 2) of num */
-static inline uint64
-sh_log2(uint64 num)
-{
-	int			i;
-	uint64		limit;
-
-	for (i = 0, limit = 1; limit < num; i++, limit <<= 1)
-		;
-	return i;
-}
-
-/* calculate first power of 2 >= num */
-static inline uint64
-sh_pow2(uint64 num)
-{
-	return ((uint64) 1) << sh_log2(num);
-}
-
 #ifdef FRONTEND
 #define sh_error(...) pg_log_error(__VA_ARGS__)
 #define sh_log(...) pg_log_info(__VA_ARGS__)
@@ -259,7 +240,7 @@ SH_COMPUTE_PARAMETERS(SH_TYPE * tb, uint32 newsize)
 	size = Max(newsize, 2);
 
 	/* round up size to the next power of 2, that's how bucketing works */
-	size = sh_pow2(size);
+	size = pg_nextpower2_64(size);
 	Assert(size <= SH_MAX_SIZE);
 
 	/*
@@ -434,7 +415,7 @@ SH_GROW(SH_TYPE * tb, uint32 newsize)
 	uint32		startelem = 0;
 	uint32		copyelem;
 
-	Assert(oldsize == sh_pow2(oldsize));
+	Assert(oldsize == pg_nextpower2_64(oldsize));
 	Assert(oldsize != SH_MAX_SIZE);
 	Assert(oldsize < newsize);
 
-- 
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