pgsql: bufmgr: Pass io_object and io_context through to PinBufferForBlo

bufmgr: Pass io_object and io_context through to PinBufferForBlock()

PinBufferForBlock() is always_inline and called in a loop in
StartReadBuffersImpl(). Previously it computed io_context and io_object
internally, which required calling IOContextForStrategy() -- a non-inline
function the compiler cannot prove is side-effect-free. This could potential
cause unneeded redundant function calls.

Compute io_context and io_object in the callers instead, allowing
StartReadBuffersImpl() to do so once before entering the loop.

Author: Melanie Plageman <melanieplageman(at)gmail(dot)com>
Suggested-by: Andres Freund <andres(at)anarazel(dot)de>
Discussion: https://postgr.es/m/zljergweqti7x67lg5ije2rzjusie37nslsnkjkkby4laqqbfw@3p3zu522yykv

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/c2a68e08b13f3cb437c92102fb11ab0f45dbd67f

Modified Files
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src/backend/storage/buffer/bufmgr.c | 45 +++++++++++++++++++++++++------------
1 file changed, 31 insertions(+), 14 deletions(-)