This reflects the change to drop FOR_EACH_IMM_USE_SAFE and adding
the DTOR to the FOR_EACH_IMM_USE_STMT iterator that cleans up
after an early break.
Built on x86_64-unknown-linux-gnu, pushed.
* doc/tree-ssa.texi: Remove outdated info on FOR_EACH_IMM_USE_STMT
iteration, clarify SSA operand parts.
* ssa-iterators.h: Update toplevel comment.
---
gcc/doc/tree-ssa.texi | 13 +++++++------
gcc/ssa-iterators.h | 30 +++++++++++-------------------
2 files changed, 18 insertions(+), 25 deletions(-)
diff --git a/gcc/doc/tree-ssa.texi b/gcc/doc/tree-ssa.texi
index dc6a111701e..25aa006d48e 100644
--- a/gcc/doc/tree-ssa.texi
+++ b/gcc/doc/tree-ssa.texi
@@ -355,7 +355,7 @@ FOR_EACH_PHI_OR_STMT_DEF (def_operand_p, phi, iter, flags)
Immediate use information is now always available. Using the immediate use
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} and call fold_stmt on
+to change each use of @code{ssa_var} to @code{val} and call fold_stmt on
each stmt after that is done:
@smallexample
@@ -367,8 +367,9 @@ each stmt after that is done:
FOR_EACH_IMM_USE_STMT (stmt, iterator, ssa_var)
@{
FOR_EACH_IMM_USE_ON_STMT (imm_use_p, iterator)
- SET_USE (imm_use_p, ssa_var_2);
+ SET_USE (imm_use_p, val);
fold_stmt (stmt);
+ update_stmt (stmt);
@}
@end smallexample
@@ -389,9 +390,7 @@ terminated early; a destructor takes care of that when
leaving the
@code{FOR_EACH_IMM_USE_STMT} scope.
There are checks in @code{verify_ssa} which verify that the immediate use list
-is up to date, as well as checking that an optimization didn't break from the
-loop without using this macro. It is safe to simply 'break'; from a
-@code{FOR_EACH_IMM_USE_FAST} traverse.
+is up to date.
Some useful functions and macros:
@enumerate
@@ -412,7 +411,9 @@ isn't located in a @code{PHI} node.
@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.
+actually inserted into the instruction stream via a @code{gsi_*} routine
+which calls @code{update_stmt} to re-scan SSA operands and update the
+immediate use lists.
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
diff --git a/gcc/ssa-iterators.h b/gcc/ssa-iterators.h
index 6b5da24a04b..77ecfac1993 100644
--- a/gcc/ssa-iterators.h
+++ b/gcc/ssa-iterators.h
@@ -36,25 +36,17 @@ along with GCC; see the file COPYING3. If not see
base for a circular list, and initially this is the only node in
the list.
- Fast iteration allows each use to be examined, but does not allow
- any modifications to the uses or stmts.
-
- Normal iteration allows insertion, deletion, and modification. the
- iterator manages this by inserting a marker node into the list
- immediately before the node currently being examined in the list.
- this marker node is uniquely identified by having null stmt *and* a
- null use pointer.
-
- When iterating to the next use, the iteration routines check to see
- if the node after the marker has changed. if it has, then the node
- following the marker is now the next one to be visited. if not, the
- marker node is moved past that node in the list (visualize it as
- bumping the marker node through the list). this continues until
- the marker node is moved to the original anchor position. the
- marker node is then removed from the list.
-
- If iteration is halted early, the marker node must be removed from
- the list before continuing. */
+ Fast iteration via FOR_EACH_IMM_USE_FAST allows each use to be
+ examined, but does not allow any modifications to the uses or stmts.
+
+ Safe iteration via FOR_EACH_IMM_USE_STMT and FOR_EACH_IMM_USE_ON_STMT
+ allows insertion, deletion, and modification of SSA operands within
+ the current stmt iterated. The iterator manages this by re-sorting
+ the immediate uses to batch uses on a single stmt after each other
+ and inserts a marker node into the list immediately after the node
+ ending the current batch. This marker node is uniquely identified by
+ having null stmt *and* a null use pointer. */
+
struct imm_use_iterator
{
/* This is the current use the iterator is processing. */
--
2.51.0
