Macro nesting hell
Last night my ancient HP compiler spit up on HEAD:
http://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=pademelon&dt=2015-07-01%2001%3A30%3A18
complaining thus:
cpp: "brin_pageops.c", line 626: error 4018: Macro param too large after substitution - use -H option.
I was able to revive pademelon by adding a new compiler flag as suggested,
but after looking at what the preprocessor is emitting, I can't say that
I blame it for being unhappy. This simple-looking line
Assert(BRIN_IS_REGULAR_PAGE(BufferGetPage(oldbuf)));
is expanding to this:
do { if (!(((((BrinSpecialSpace *) ( ((void) ((bool) (! (!(((const void*)(((Page)( ((void) ((bool) (! (!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition("!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)", ("FailedAssertion"), "brin_pageops.c", 626), 0)))), (oldbuf) != 0 ))) || (ExceptionalCondition("!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), (oldbuf) != 0 ))", ("FailedAssertion"), "brin_pageops.c", 626), 0)))), ((oldbuf) < 0) ? LocalBufferBlockPointers[-(oldbuf) - 1] : (Block) (BufferBlocks + ((Size) ((oldbuf) - 1)) * 8192) ))) != ((void *)0)))) || (ExceptionalCondition("!(((const void*)(((Page)( ((void) ((bool) (! (!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\"!((oldbuf) <= NBuffers && (oldbuf) !
= -NLocBuffer)\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), (oldbuf) != 0 ))) || (ExceptionalCondition(\"!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\\\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\\\", (\\\"FailedAssertion\\\"), \\\"brin_pageops.c\\\", 626), 0)))), (oldbuf) != 0 ))\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), ((oldbuf) < 0) ? LocalBufferBlockPointers[-(oldbuf) - 1] : (Block) (BufferBlocks + ((Size) ((oldbuf) - 1)) * 8192) ))) != ((void *)0)))", ("FailedAssertion"), "brin_pageops.c", 626), 0)))), ((void) ((bool) (! (!(((PageHeader) (((Page)( ((void) ((bool) (! (!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition("!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)", ("FailedAssertion"), "brin_pageops.c", 626), 0)))), (oldbuf) != 0 ))) || (ExceptionalCondition("!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >!
= -NLocBuffer)) || (ExceptionalCondition(\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), (oldbuf) != 0 ))", ("FailedAssertion"), "brin_pageops.c", 626), 0)))), ((oldbuf) < 0) ? LocalBufferBlockPointers[-(oldbuf) - 1] : (Block) (BufferBlocks + ((Size) ((oldbuf) - 1)) * 8192) ))))->pd_special <= 8192)) || (ExceptionalCondition("!(((PageHeader) (((Page)( ((void) ((bool) (! (!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), (oldbuf) != 0 ))) || (ExceptionalCondition(\"!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\\\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\\\", (\\\"FailedAssertion\\\"), \\\"brin_pageops.c\\\", 626), 0)))), (oldbuf) != 0 ))\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), ((oldbuf) < 0) ? LocalBufferBlockPointers[-(oldbuf) - 1] : (Bl!
ock) (BufferBlocks + ((Size) ((oldbuf) - 1)) * 8192) ))))->pd_special <= 8192)", ("FailedAssertion"), "brin_pageops.c", 626), 0)))), ((void) ((bool) (! (!(((PageHeader) (((Page)( ((void) ((bool) (! (!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition("!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)", ("FailedAssertion"), "brin_pageops.c", 626), 0)))), (oldbuf) != 0 ))) || (ExceptionalCondition("!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), (oldbuf) != 0 ))", ("FailedAssertion"), "brin_pageops.c", 626), 0)))), ((oldbuf) < 0) ? LocalBufferBlockPointers[-(oldbuf) - 1] : (Block) (BufferBlocks + ((Size) ((oldbuf) - 1)) * 8192) ))))->pd_special >= (__builtin_offsetof (PageHeaderData, pd_linp)))) || (ExceptionalCondition("!(((PageHeader) (((Page)( ((void) ((bool) (!!
(!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), (oldbuf) != 0 ))) || (ExceptionalCondition(\"!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\\\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\\\", (\\\"FailedAssertion\\\"), \\\"brin_pageops.c\\\", 626), 0)))), (oldbuf) != 0 ))\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), ((oldbuf) < 0) ? LocalBufferBlockPointers[-(oldbuf) - 1] : (Block) (BufferBlocks + ((Size) ((oldbuf) - 1)) * 8192) ))))->pd_special >= (__builtin_offsetof (PageHeaderData, pd_linp)))", ("FailedAssertion"), "brin_pageops.c", 626), 0)))), (char *) ((char *) (((Page)( ((void) ((bool) (! (!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition("!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)", ("FailedAssertion"), "brin_pageops.c", 626), 0)))), (oldb!
uf) != 0 ))) || (ExceptionalCondition("!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), (oldbuf) != 0 ))", ("FailedAssertion"), "brin_pageops.c", 626), 0)))), ((oldbuf) < 0) ? LocalBufferBlockPointers[-(oldbuf) - 1] : (Block) (BufferBlocks + ((Size) ((oldbuf) - 1)) * 8192) ))) + ((PageHeader) (((Page)( ((void) ((bool) (! (!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition("!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)", ("FailedAssertion"), "brin_pageops.c", 626), 0)))), (oldbuf) != 0 ))) || (ExceptionalCondition("!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), (oldbuf) != 0 ))", ("FailedAssertion!
"), "brin_pageops.c", 626), 0)))), ((oldbuf) < 0) ? LocalBufferBlockPointers[-(oldbuf) - 1] : (Block) (BufferBlocks + ((Size) ((oldbuf) - 1)) * 8192) ))))->pd_special) ))->vector[(((uintptr_t) ((1)) + ((8) - 1)) & ~((uintptr_t) ((8) - 1))) / sizeof(uint16) - 1]) == 0xF093))) ExceptionalCondition("!(((((BrinSpecialSpace *) ( ((void) ((bool) (! (!(((const void*)(((Page)( ((void) ((bool) (! (!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), (oldbuf) != 0 ))) || (ExceptionalCondition(\"!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\\\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\\\", (\\\"FailedAssertion\\\"), \\\"brin_pageops.c\\\", 626), 0)))), (oldbuf) != 0 ))\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), ((oldbuf) < 0) ? LocalBufferBlockPointers[-(oldbuf) - 1] : (Block) (BufferBlocks + ((Size) ((oldbuf) - 1)) *!
8192) ))) != ((void *)0)))) || (ExceptionalCondition(\"!(((const void*)(((Page)( ((void) ((bool) (! (!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\\\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\\\", (\\\"FailedAssertion\\\"), \\\"brin_pageops.c\\\", 626), 0)))), (oldbuf) != 0 ))) || (ExceptionalCondition(\\\"!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\\\\\\\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\\\\\\\", (\\\\\\\"FailedAssertion\\\\\\\"), \\\\\\\"brin_pageops.c\\\\\\\", 626), 0)))), (oldbuf) != 0 ))\\\", (\\\"FailedAssertion\\\"), \\\"brin_pageops.c\\\", 626), 0)))), ((oldbuf) < 0) ? LocalBufferBlockPointers[-(oldbuf) - 1] : (Block) (BufferBlocks + ((Size) ((oldbuf) - 1)) * 8192) ))) != ((void *)0)))\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), ((void) ((bool) (! (!(((PageHeader) (((Page)( ((void) ((bool) (! (!(( ((void) ((bool!
) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), (oldbuf) != 0 ))) || (ExceptionalCondition(\"!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\\\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\\\", (\\\"FailedAssertion\\\"), \\\"brin_pageops.c\\\", 626), 0)))), (oldbuf) != 0 ))\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), ((oldbuf) < 0) ? LocalBufferBlockPointers[-(oldbuf) - 1] : (Block) (BufferBlocks + ((Size) ((oldbuf) - 1)) * 8192) ))))->pd_special <= 8192)) || (ExceptionalCondition(\"!(((PageHeader) (((Page)( ((void) ((bool) (! (!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\\\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\\\", (\\\"FailedAssertion\\\"), \\\"brin_pageops.c\\\", 626), 0)))), (oldbuf) != 0 ))) || (ExceptionalCondition(\\\"!(( ((void) ((bool) (! (!((oldb!
uf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\\\\\\\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\\\\\\\", (\\\\\\\"FailedAssertion\\\\\\\"), \\\\\\\"brin_pageops.c\\\\\\\", 626), 0)))), (oldbuf) != 0 ))\\\", (\\\"FailedAssertion\\\"), \\\"brin_pageops.c\\\", 626), 0)))), ((oldbuf) < 0) ? LocalBufferBlockPointers[-(oldbuf) - 1] : (Block) (BufferBlocks + ((Size) ((oldbuf) - 1)) * 8192) ))))->pd_special <= 8192)\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), ((void) ((bool) (! (!(((PageHeader) (((Page)( ((void) ((bool) (! (!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), (oldbuf) != 0 ))) || (ExceptionalCondition(\"!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\\\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\\\",!
(\\\"FailedAssertion\\\"), \\\"brin_pageops.c\\\", 626), 0)))), (oldbuf) != 0 ))\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), ((oldbuf) < 0) ? LocalBufferBlockPointers[-(oldbuf) - 1] : (Block) (BufferBlocks + ((Size) ((oldbuf) - 1)) * 8192) ))))->pd_special >= (__builtin_offsetof (PageHeaderData, pd_linp)))) || (ExceptionalCondition(\"!(((PageHeader) (((Page)( ((void) ((bool) (! (!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\\\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\\\", (\\\"FailedAssertion\\\"), \\\"brin_pageops.c\\\", 626), 0)))), (oldbuf) != 0 ))) || (ExceptionalCondition(\\\"!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\\\\\\\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\\\\\\\", (\\\\\\\"FailedAssertion\\\\\\\"), \\\\\\\"brin_pageops.c\\\\\\\", 626), 0)))), (oldbuf) != 0 ))\\\", (\\\"FailedAssertion\\\"), \\\"brin_pageops.c\\\", 626), 0)))), ((oldbuf) < 0) ? LocalBufferBlockPointers[-(oldbuf) - !
1] : (Block) (BufferBlocks + ((Size) ((oldbuf) - 1)) * 8192) ))))->pd_special >= (__builtin_offsetof (PageHeaderData, pd_linp)))\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), (char *) ((char *) (((Page)( ((void) ((bool) (! (!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), (oldbuf) != 0 ))) || (ExceptionalCondition(\"!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\\\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\\\", (\\\"FailedAssertion\\\"), \\\"brin_pageops.c\\\", 626), 0)))), (oldbuf) != 0 ))\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), ((oldbuf) < 0) ? LocalBufferBlockPointers[-(oldbuf) - 1] : (Block) (BufferBlocks + ((Size) ((oldbuf) - 1)) * 8192) ))) + ((PageHeader) (((Page)( ((void) ((bool) (! (!(( ((void) ((bool) (! (!((!
oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), (oldbuf) != 0 ))) || (ExceptionalCondition(\"!(( ((void) ((bool) (! (!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)) || (ExceptionalCondition(\\\"!((oldbuf) <= NBuffers && (oldbuf) >= -NLocBuffer)\\\", (\\\"FailedAssertion\\\"), \\\"brin_pageops.c\\\", 626), 0)))), (oldbuf) != 0 ))\", (\"FailedAssertion\"), \"brin_pageops.c\", 626), 0)))), ((oldbuf) < 0) ? LocalBufferBlockPointers[-(oldbuf) - 1] : (Block) (BufferBlocks + ((Size) ((oldbuf) - 1)) * 8192) ))))->pd_special) ))->vector[(((uintptr_t) ((1)) + ((8) - 1)) & ~((uintptr_t) ((8) - 1))) / sizeof(uint16) - 1]) == 0xF093))", ("FailedAssertion"), "brin_pageops.c", 626); } while (0);
The problem here is that we've got several nested levels of macros that
each feel free to evaluate their arguments multiple times. Quite aside
from the risk of breaking toolchains, this has got to be inefficient.
A quick look at the generated source code shows five separate occurrences
of the sequence
testl %ebp, %ebp
jns .L80
movq LocalBufferBlockPointers(%rip), %rax
movq 40(%rsp), %rdx
movq (%rax,%rdx), %rax
jmp .L81
.L80:
movq 24(%rsp), %rax
addq BufferBlocks(%rip), %rax
corresponding to the BufferGetBlock() macro. At least gcc seems to
have figured out that it only needed to test BufferIsValid(buffer)
once, but still, this is awful.
And then there's the risk of outright bugs from multiple evaluations
of arguments.
I'm thinking we really ought to mount a campaign to replace some of these
macros with inlined-if-possible functions.
regards, tom lane
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Tom Lane wrote:
Last night my ancient HP compiler spit up on HEAD:
http://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=pademelon&dt=2015-07-01%2001%3A30%3A18
complaining thus:
cpp: "brin_pageops.c", line 626: error 4018: Macro param too large after substitution - use -H option.
I was able to revive pademelon by adding a new compiler flag as suggested,
but after looking at what the preprocessor is emitting, I can't say that
I blame it for being unhappy. This simple-looking lineAssert(BRIN_IS_REGULAR_PAGE(BufferGetPage(oldbuf)));
is expanding to this:
Wow, that's kind of amazing. I think this particular case boils down to
just PageGetSpecialPointer (bufpage.h) and BufferGetBlock (bufmgr.h).
I'm thinking we really ought to mount a campaign to replace some of these
macros with inlined-if-possible functions.
My guess is that changing a very small amount of them will do a large
enough portion of the job.
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PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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On 2015-07-01 12:55:48 -0300, Alvaro Herrera wrote:
Tom Lane wrote:
Last night my ancient HP compiler spit up on HEAD:
http://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=pademelon&dt=2015-07-01%2001%3A30%3A18
complaining thus:
cpp: "brin_pageops.c", line 626: error 4018: Macro param too large after substitution - use -H option.
I was able to revive pademelon by adding a new compiler flag as suggested,
but after looking at what the preprocessor is emitting, I can't say that
I blame it for being unhappy. This simple-looking lineAssert(BRIN_IS_REGULAR_PAGE(BufferGetPage(oldbuf)));
is expanding to this:
I just hit this in clang which also warns about too long literals unless
you silence it...
Wow, that's kind of amazing. I think this particular case boils down to
just PageGetSpecialPointer (bufpage.h) and BufferGetBlock (bufmgr.h).
Inlining just BufferGetBlock already helps sufficiently to press it
below 4k (the standard's limit IIRC), but that doesn't mean we shouldn't
go a bit further.
I'm thinking we really ought to mount a campaign to replace some of these
macros with inlined-if-possible functions.My guess is that changing a very small amount of them will do a large
enough portion of the job.
I think it'd be good to convert the macros in bufpage.h and bufmgr.h
that either currently have multiple evaluation hazards, or have a
AssertMacro() in them. The former for obvious reasons, the latter
because that immediately makes them rather large (on and it implies
multiple evaluation hazards anyway).
That'd mean inlining PageSetPageSizeAndVersion(), PageGetSpecialSize(),
PageGetSpecialPointer(), PageGetItem(), PageGetMaxOffsetNumber(),
PageIsPrunable(), PageSetPrunable(), PageClearPrunable(),
BufferIsValid(), BufferGetBlock(), BufferGetPageSize().
Greetings,
Andres Freund
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Andres Freund <andres@anarazel.de> writes:
On 2015-07-01 12:55:48 -0300, Alvaro Herrera wrote:
Tom Lane wrote:
I'm thinking we really ought to mount a campaign to replace some of these
macros with inlined-if-possible functions.
My guess is that changing a very small amount of them will do a large
enough portion of the job.
I think it'd be good to convert the macros in bufpage.h and bufmgr.h
that either currently have multiple evaluation hazards, or have a
AssertMacro() in them. The former for obvious reasons, the latter
because that immediately makes them rather large (on and it implies
multiple evaluation hazards anyway).
That'd mean inlining PageSetPageSizeAndVersion(), PageGetSpecialSize(),
PageGetSpecialPointer(), PageGetItem(), PageGetMaxOffsetNumber(),
PageIsPrunable(), PageSetPrunable(), PageClearPrunable(),
BufferIsValid(), BufferGetBlock(), BufferGetPageSize().
Sounds reasonable to me. If you do this, I'll see whether pademelon
can be adjusted to build using the minimum macro expansion buffer
size specified by the C standard.
regards, tom lane
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... btw, why don't we convert c.h's Max(), Min(), and Abs() to inlines?
They've all got multi-eval hazards.
It might also be interesting to research whether inline would allow
simplifying the MemSetFoo family.
regards, tom lane
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On 2015-08-12 10:18:12 -0400, Tom Lane wrote:
Andres Freund <andres@anarazel.de> writes:
On 2015-07-01 12:55:48 -0300, Alvaro Herrera wrote:
Tom Lane wrote:
I'm thinking we really ought to mount a campaign to replace some of these
macros with inlined-if-possible functions.My guess is that changing a very small amount of them will do a large
enough portion of the job.I think it'd be good to convert the macros in bufpage.h and bufmgr.h
that either currently have multiple evaluation hazards, or have a
AssertMacro() in them. The former for obvious reasons, the latter
because that immediately makes them rather large (on and it implies
multiple evaluation hazards anyway).That'd mean inlining PageSetPageSizeAndVersion(), PageGetSpecialSize(),
PageGetSpecialPointer(), PageGetItem(), PageGetMaxOffsetNumber(),
PageIsPrunable(), PageSetPrunable(), PageClearPrunable(),
BufferIsValid(), BufferGetBlock(), BufferGetPageSize().Sounds reasonable to me. If you do this, I'll see whether pademelon
can be adjusted to build using the minimum macro expansion buffer
size specified by the C standard.
Here's the patch attached.
There's two more macros on the list that I had missed:
PageXLogRecPtrSet(), PageXLogRecPtrGet(). Unfortunately *Set() requires
to pas a pointer to the PageXLogRecPtr - there's only two callers tho.
We could instead just leave these, or add an indirecting macro. Seems
fine to me though.
With it applied pg compiles without the warning I saw before:
/home/andres/src/postgresql/src/backend/access/brin/brin_pageops.c:778:5: warning: string literal of length 7732 exceeds maximum length 4095
that ISO C99 compilers are required to support [-Woverlength-strings]
Assert(BRIN_IS_REGULAR_PAGE(BufferGetPage(oldbuf)));
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We could obviously be more aggressive and convert all the applicable
defines, but they are already readable and have no multiple eval
hazards, so I'm not inclined to that.
Andres
Attachments:
0001-Change-some-buffer-and-page-related-macros-to-inline.patchtext/x-patch; charset=us-asciiDownload
>From 8203fd286c276051060a6fe8c98c8b576c644f14 Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Thu, 13 Aug 2015 01:37:44 +0200
Subject: [PATCH] Change some buffer and page related macros to inline
functions.
Firstly some of these macros could recursively expand to string literals
larger than the minimum required to be supported by an environment by
the C standard. That's primarily due to included assertions. Secondly
some macros had multiple evaluation hazards.
This required one minor API change in that PageXLogRecPtrSet now takes a
pointer to a PageXLogRecPtr instead the value directly. There shouldn't
be callers to it out there...
Discussion: 4407.1435763473@sss.pgh.pa.us
---
src/include/access/gist.h | 2 +-
src/include/storage/bufmgr.h | 29 +++++-----
src/include/storage/bufpage.h | 124 ++++++++++++++++++++++++++----------------
3 files changed, 95 insertions(+), 60 deletions(-)
diff --git a/src/include/access/gist.h b/src/include/access/gist.h
index 81e559b..33eb9d3 100644
--- a/src/include/access/gist.h
+++ b/src/include/access/gist.h
@@ -142,7 +142,7 @@ typedef struct GISTENTRY
#define GistClearFollowRight(page) ( GistPageGetOpaque(page)->flags &= ~F_FOLLOW_RIGHT)
#define GistPageGetNSN(page) ( PageXLogRecPtrGet(GistPageGetOpaque(page)->nsn))
-#define GistPageSetNSN(page, val) ( PageXLogRecPtrSet(GistPageGetOpaque(page)->nsn, val))
+#define GistPageSetNSN(page, val) ( PageXLogRecPtrSet(&GistPageGetOpaque(page)->nsn, val))
/*
* Vector of GISTENTRY structs; user-defined methods union and picksplit
diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index ec0a254..235264c 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -96,11 +96,12 @@ extern PGDLLIMPORT int32 *LocalRefCount;
* even in non-assert-enabled builds can be significant. Thus, we've
* now demoted the range checks to assertions within the macro itself.
*/
-#define BufferIsValid(bufnum) \
-( \
- AssertMacro((bufnum) <= NBuffers && (bufnum) >= -NLocBuffer), \
- (bufnum) != InvalidBuffer \
-)
+static inline bool
+BufferIsValid(Buffer bufnum)
+{
+ AssertArg(bufnum <= NBuffers && bufnum >= -NLocBuffer);
+ return bufnum != InvalidBuffer;
+}
/*
* BufferGetBlock
@@ -109,14 +110,16 @@ extern PGDLLIMPORT int32 *LocalRefCount;
* Note:
* Assumes buffer is valid.
*/
-#define BufferGetBlock(buffer) \
-( \
- AssertMacro(BufferIsValid(buffer)), \
- BufferIsLocal(buffer) ? \
- LocalBufferBlockPointers[-(buffer) - 1] \
- : \
- (Block) (BufferBlocks + ((Size) ((buffer) - 1)) * BLCKSZ) \
-)
+static inline Block
+BufferGetBlock(Buffer buffer)
+{
+ AssertArg(BufferIsValid(buffer));
+
+ if (BufferIsLocal(buffer))
+ return LocalBufferBlockPointers[-buffer - 1];
+ else
+ return (Block) (BufferBlocks + ((Size) (buffer - 1)) * BLCKSZ);
+}
/*
* BufferGetPageSize
diff --git a/src/include/storage/bufpage.h b/src/include/storage/bufpage.h
index a2f78ee..4d104b8 100644
--- a/src/include/storage/bufpage.h
+++ b/src/include/storage/bufpage.h
@@ -14,6 +14,7 @@
#ifndef BUFPAGE_H
#define BUFPAGE_H
+#include "access/transam.h"
#include "access/xlogdefs.h"
#include "storage/block.h"
#include "storage/item.h"
@@ -93,10 +94,18 @@ typedef struct
uint32 xrecoff; /* low bits */
} PageXLogRecPtr;
-#define PageXLogRecPtrGet(val) \
- ((uint64) (val).xlogid << 32 | (val).xrecoff)
-#define PageXLogRecPtrSet(ptr, lsn) \
- ((ptr).xlogid = (uint32) ((lsn) >> 32), (ptr).xrecoff = (uint32) (lsn))
+static inline XLogRecPtr
+PageXLogRecPtrGet(PageXLogRecPtr pageptr)
+{
+ return ((uint64) pageptr.xlogid) << 32 | pageptr.xrecoff;
+}
+
+static inline void
+PageXLogRecPtrSet(PageXLogRecPtr *pageptr, XLogRecPtr lsn)
+{
+ pageptr->xlogid = (uint32) (lsn >> 32);
+ pageptr->xrecoff = (uint32) lsn;
+}
/*
* disk page organization
@@ -197,7 +206,7 @@ typedef PageHeaderData *PageHeader;
#define PG_DATA_CHECKSUM_VERSION 1
/* ----------------------------------------------------------------
- * page support macros
+ * page support macros & inline functions
* ----------------------------------------------------------------
*/
@@ -279,12 +288,13 @@ typedef PageHeaderData *PageHeader;
* We could support setting these two values separately, but there's
* no real need for it at the moment.
*/
-#define PageSetPageSizeAndVersion(page, size, version) \
-( \
- AssertMacro(((size) & 0xFF00) == (size)), \
- AssertMacro(((version) & 0x00FF) == (version)), \
- ((PageHeader) (page))->pd_pagesize_version = (size) | (version) \
-)
+static inline void
+PageSetPageSizeAndVersion(Page page, Size size, int version)
+{
+ Assert((size & 0xFF00) == size);
+ Assert((version & 0x00FF) == version);
+ ((PageHeader) page)->pd_pagesize_version = size | version;
+}
/* ----------------
* page special data macros
@@ -294,20 +304,26 @@ typedef PageHeaderData *PageHeader;
* PageGetSpecialSize
* Returns size of special space on a page.
*/
-#define PageGetSpecialSize(page) \
- ((uint16) (PageGetPageSize(page) - ((PageHeader)(page))->pd_special))
+static inline uint16
+PageGetSpecialSize(Page page)
+{
+ return (uint16) (PageGetPageSize(page) - ((PageHeader) page)->pd_special);
+}
/*
* PageGetSpecialPointer
* Returns pointer to special space on a page.
*/
-#define PageGetSpecialPointer(page) \
-( \
- AssertMacro(PageIsValid(page)), \
- AssertMacro(((PageHeader) (page))->pd_special <= BLCKSZ), \
- AssertMacro(((PageHeader) (page))->pd_special >= SizeOfPageHeaderData), \
- (char *) ((char *) (page) + ((PageHeader) (page))->pd_special) \
-)
+static inline char *
+PageGetSpecialPointer(Page page)
+{
+ PageHeader ph = (PageHeader) page;
+
+ Assert(PageIsValid(page));
+ Assert(ph->pd_special <= BLCKSZ);
+ Assert(ph->pd_special >= SizeOfPageHeaderData);
+ return ((char *) page) + ph->pd_special;
+}
/*
* PageGetItem
@@ -317,12 +333,13 @@ typedef PageHeaderData *PageHeader;
* This does not change the status of any of the resources passed.
* The semantics may change in the future.
*/
-#define PageGetItem(page, itemId) \
-( \
- AssertMacro(PageIsValid(page)), \
- AssertMacro(ItemIdHasStorage(itemId)), \
- (Item)(((char *)(page)) + ItemIdGetOffset(itemId)) \
-)
+static inline Item
+PageGetItem(Page page, ItemId itemId)
+{
+ Assert(PageIsValid(page));
+ Assert(ItemIdHasStorage(itemId));
+ return (Item)(((char *) page) + ItemIdGetOffset(itemId));
+}
/*
* PageGetMaxOffsetNumber
@@ -334,19 +351,24 @@ typedef PageHeaderData *PageHeader;
* return zero to ensure sane behavior. Accept double evaluation
* of the argument so that we can ensure this.
*/
-#define PageGetMaxOffsetNumber(page) \
- (((PageHeader) (page))->pd_lower <= SizeOfPageHeaderData ? 0 : \
- ((((PageHeader) (page))->pd_lower - SizeOfPageHeaderData) \
- / sizeof(ItemIdData)))
+static inline LocationIndex
+PageGetMaxOffsetNumber(Page page)
+{
+ PageHeader ph = (PageHeader) page;
+
+ if (ph->pd_lower <= SizeOfPageHeaderData)
+ return 0;
+ else
+ return (ph->pd_lower - SizeOfPageHeaderData) / sizeof(ItemIdData);
+}
/*
- * Additional macros for access to page headers. (Beware multiple evaluation
- * of the arguments!)
+ * Additional page header accessors
*/
#define PageGetLSN(page) \
PageXLogRecPtrGet(((PageHeader) (page))->pd_lsn)
#define PageSetLSN(page, lsn) \
- PageXLogRecPtrSet(((PageHeader) (page))->pd_lsn, lsn)
+ PageXLogRecPtrSet(&((PageHeader) (page))->pd_lsn, lsn)
#define PageHasFreeLinePointers(page) \
(((PageHeader) (page))->pd_flags & PD_HAS_FREE_LINES)
@@ -369,19 +391,29 @@ typedef PageHeaderData *PageHeader;
#define PageClearAllVisible(page) \
(((PageHeader) (page))->pd_flags &= ~PD_ALL_VISIBLE)
-#define PageIsPrunable(page, oldestxmin) \
-( \
- AssertMacro(TransactionIdIsNormal(oldestxmin)), \
- TransactionIdIsValid(((PageHeader) (page))->pd_prune_xid) && \
- TransactionIdPrecedes(((PageHeader) (page))->pd_prune_xid, oldestxmin) \
-)
-#define PageSetPrunable(page, xid) \
-do { \
- Assert(TransactionIdIsNormal(xid)); \
- if (!TransactionIdIsValid(((PageHeader) (page))->pd_prune_xid) || \
- TransactionIdPrecedes(xid, ((PageHeader) (page))->pd_prune_xid)) \
- ((PageHeader) (page))->pd_prune_xid = (xid); \
-} while (0)
+static inline bool
+PageIsPrunable(Page page, TransactionId oldestxmin)
+{
+ TransactionId prune_xid = ((PageHeader) page)->pd_prune_xid;
+
+ Assert(TransactionIdIsNormal(oldestxmin));
+
+ return TransactionIdIsValid(prune_xid) &&
+ TransactionIdPrecedes(prune_xid, oldestxmin);
+}
+
+static inline void
+PageSetPrunable(Page page, TransactionId xid)
+{
+ PageHeader ph = (PageHeader) page;
+
+ Assert(TransactionIdIsNormal(xid));
+
+ if (!TransactionIdIsValid(ph->pd_prune_xid) ||
+ TransactionIdPrecedes(xid, ph->pd_prune_xid))
+ ph->pd_prune_xid = xid;
+}
+
#define PageClearPrunable(page) \
(((PageHeader) (page))->pd_prune_xid = InvalidTransactionId)
--
2.3.0.149.gf3f4077.dirty
Andres Freund <andres@anarazel.de> writes:
On 2015-08-12 10:18:12 -0400, Tom Lane wrote:
Sounds reasonable to me. If you do this, I'll see whether pademelon
can be adjusted to build using the minimum macro expansion buffer
size specified by the C standard.
Here's the patch attached.
Looks like you need to pay more attention to the surrounding comments:
some of them still refer to the code as a macro, and I see at least one
place that explicitly mentions double-eval hazards that this presumably
removes. (I think your previous patch re fastgetattr was also a bit weak
on the comments, btw.)
regards, tom lane
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