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tree-ssa.texi: Grammer/abbreviation updates.

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2005-04-15  Andrew Macleod  <amacleod@redhat.com>

	* doc/tree-ssa.texi: Grammer/abbreviation updates.

From-SVN: r98190
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Andrew MacLeod 2005-04-15 16:29:34 +00:00 committed by Andrew Macleod
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2 changed files with 27 additions and 16 deletions
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@ -1,3 +1,7 @@
2005-04-15 Andrew Macleod <amacleod@redhat.com>
* doc/tree-ssa.texi: Grammer/abbreviation updates.
2005-04-15 Diego Novillo <dnovillo@redhat.com>
* tree-vect-transform.c (vectorizable_store): Mark necessary

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gcc/doc/tree-ssa.texi
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@ -886,11 +886,11 @@ print_ops (tree stmt)
@}
@end smallexample
Operands use to be updated lazily via calls to @code{get_stmt_operands}.
This function is now deprecated and operands are updated as soon as the stmt is
finished via a call to @code{update_stmt}. If statement elements are
changed via @code{SET_USE} or @code{SET_DEF}, no further action need be
taken (ie, those macros take care of whatever updating is required). If
Operands were once updated lazily via calls to @code{get_stmt_operands}.
This function is now deprecated and operands are updated as soon as the
statement is finished via a call to @code{update_stmt}. If statement elements
are changed via @code{SET_USE} or @code{SET_DEF}, then no further action is
required (ie, those macros take care of updating the statement). If
changes are made by manipulating the statement's tree directly, then a call
must be made to @code{update_stmt} when complete. Calling one of the
@code{bsi_insert} routines or @code{bsi_replace} performs an implicit call
@ -1033,6 +1033,10 @@ iterators, you may examine every use of any @code{SSA_NAME}. For instance,
to change each use of @code{ssa_var} to @code{ssa_var2}:
@smallexample
use_operand_p imm_use_p;
imm_use_iterator iterator;
tree ssa_var
FOR_EACH_IMM_USE_SAFE (imm_use_p, iterator, ssa_var)
SET_USE (imm_use_p, ssa_var_2);
@end smallexample
@ -1073,27 +1077,30 @@ Some useful functions and macros:
single use of @code{ssa_var}.
@item @code{single_imm_use (ssa_var, use_operand_p *ptr, tree *stmt)} :
Returns true if there is only a single use of @code{ssa_var}, and also returns
the use pointer and stmt it occurs in in the second and third parameters.
the use pointer and statement it occurs in in the second and third parameters.
@item @code{num_imm_uses (ssa_var)} : Returns the number of immediate uses of
@code{ssa_var}. Its better not to use this if possible since it simply
@code{ssa_var}. It is better not to use this if possible since it simply
utilizes a loop to count the uses.
@item @code{PHI_ARG_INDEX_FROM_USE (use_p)} : Given a use within a @code{PHI}
node, return the index number for the use. An assert is triggered if the use
isn't located in a @code{PHI} node.
@item @code{USE_STMT (use_p)} : Return the stmt a use occurs in.
@item @code{USE_STMT (use_p)} : Return the statement a use occurs in.
@end enumerate
Note that uses are not put into an immediate use list until their statement is
actually inserted into the instruction stream via a @code{bsi_*} routine.
It is also still possible to utilize lazy updating of stmts, but this should be used only when absolutely required. Both alias analysis and the dominator
optimizations currently do this.
It is also still possible to utilize lazy updating of statements, but this
should be used only when absolutely required. Both alias analysis and the
dominator optimizations currently do this.
When lazy updating is being used, the immediate use information is out of date
and cannot be used reliably. Lazy updating is achieved by simply marking stmts
modified via calls to @code{mark_stmt_modified} instead of @code{update_stmt}.
When lazy updating is no longer required, all the modified stmts must have
@code{update_stmt} called in order to bring them up to date. This must be done before the optimization is finished, or @code{verify_ssa} will trigger an abort.
and cannot be used reliably. Lazy updating is achieved by simply marking
statements modified via calls to @code{mark_stmt_modified} instead of
@code{update_stmt}. When lazy updating is no longer required, all the
modified statements must have @code{update_stmt} called in order to bring them
up to date. This must be done before the optimization is finished, or
@code{verify_ssa} will trigger an abort.
This is done with a simple loop over the instruction stream:
@smallexample