@@ -78,20 +78,24 @@ extern PGDLLIMPORT int32 *LocalRefCount;
7878 * True iff the given buffer number is valid (either as a shared
7979 * or local buffer).
8080 *
81- * This is not quite the inverse of the BufferIsInvalid() macro, since this
82- * adds sanity rangechecks on the buffer number.
83- *
8481 * Note: For a long time this was defined the same as BufferIsPinned,
8582 * that is it would say False if you didn't hold a pin on the buffer.
8683 * I believe this was bogus and served only to mask logic errors.
8784 * Code should always know whether it has a buffer reference,
8885 * independently of the pin state.
86+ *
87+ * Note: For a further long time this was not quite the inverse of the
88+ * BufferIsInvalid() macro, in that it also did sanity checks to verify
89+ * that the buffer number was in range. Most likely, this macro was
90+ * originally intended only to be used in assertions, but its use has
91+ * since expanded quite a bit, and the overhead of making those checks
92+ * even in non-assert-enabled builds can be significant. Thus, we've
93+ * now demoted the range checks to assertions within the macro itself.
8994 */
9095#define BufferIsValid (bufnum ) \
9196( \
92- (bufnum) != InvalidBuffer && \
93- (bufnum) >= -NLocBuffer && \
94- (bufnum) <= NBuffers \
97+ AssertMacro((bufnum) <= NBuffers && (bufnum) >= -NLocBuffer), \
98+ (bufnum) != InvalidBuffer \
9599)
96100
97101/*
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