I have pushed the tree.h comments in g:6a2053773b8. I will wait
for an approval of the changes to the manual.
On 1/27/21 5:54 PM, Martin Sebor wrote:
Attached is an updated patch for both tree.h and the internals manual
documenting the most important BLOCK_ macros and what they represent.
On 1/21/21 2:52 PM, Martin Sebor wrote:
On 1/18/21 6:25 AM, Richard Biener wrote:
PS Here are my notes on the macros and the two related functions:
BLOCK: Denotes a lexical scope. Contains BLOCK_VARS of variables
declared in it, BLOCK_SUBBLOCKS of scopes nested in it, and
BLOCK_CHAIN pointing to the next BLOCK. Its BLOCK_SUPERCONTEXT
point to the BLOCK of the enclosing scope. May have
a BLOCK_ABSTRACT_ORIGIN and a BLOCK_SOURCE_LOCATION.
BLOCK_SUPERCONTEXT: The scope of the enclosing block, or FUNCTION_DECL
for the "outermost" function scope. Inlined functions are chained by
this so that given expression E and its TREE_BLOCK(E) B,
BLOCK_SUPERCONTEXT(B) is the scope (BLOCK) in which E has been made
or into which E has been inlined. In the latter case,
BLOCK_ORIGIN(B) evaluates either to the enclosing BLOCK or to
the enclosing function DECL. It's never null.
BLOCK_ABSTRACT_ORIGIN(B) is the FUNCTION_DECL of the function into
which it has been inlined, or null if B is not inlined.
It's the BLOCK or FUNCTION it was inlined _from_, not were it was
inlined to.
It's the "ultimate" source, thus the abstract copy of the block or
function decl
(for the outermost scope, aka inlined_function_outer_scope_p). It
corresponds
to what you'd expect for the DWARF abstract origin.
Thanks for the correction! It's just the "innermost" block that
points to the "ultimate" destination into which it's been inlined.
BLOCK_ABSTRACT_ORIGIN can be NULL (in case it isn't an inline instance).
BLOCK_ABSTRACT_ORIGIN: A BLOCK, or FUNCTION_DECL of the function
into which a block has been inlined. In a BLOCK immediately enclosing
an inlined leaf expression points to the outermost BLOCK into which it
has been inlined (thus bypassing all intermediate BLOCK_SUPERCONTEXTs).
BLOCK_FRAGMENT_ORIGIN: ???
BLOCK_FRAGMENT_CHAIN: ???
that's for scope blocks split by hot/cold partitioning and only
temporarily
populated.
Thanks, I now see these documented in detail in tree.h.
bool inlined_function_outer_scope_p(BLOCK) [tree.h]
Returns true if a BLOCK has a source location.
True for all but the innermost (no SUBBLOCKs?) and outermost blocks
into which an expression has been inlined. (Is this always true?)
tree block_ultimate_origin(BLOCK) [tree.c]
Returns BLOCK_ABSTRACT_ORIGIN(BLOCK), AO, after asserting that
(DECL_P(AO) && DECL_ORIGIN(AO) == AO) || BLOCK_ORIGIN(AO) == AO).
The attached diff adds the comments above to tree.h.
I looked for a good place in the manual to add the same text but I'm
not sure. Would the Blocks @subsection in generic.texi be appropriate?
Martin
