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Sanity check re support for precise exceptions, resulting in more

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comments.  No functionality change.



git-svn-id: svn://svn.valgrind.org/vex/trunk@680
This commit is contained in:
Julian Seward
2004-12-29 17:34:50 +00:00
parent c48d6e72eb
commit 42eafce9cc
1 changed files with 20 additions and 6 deletions
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26
VEX/priv/ir/iropt.c
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@@ -125,7 +125,16 @@
* Flatten into atomic form.
*/
/* Implementation notes, 12 Oct 04.
/* Implementation notes, 29 Dec 04.
TODO (important): I think rPutI removal ignores precise exceptions
and is therefore in a sense, wrong. In the sense that PutIs are
assumed not to write parts of the guest state that we need to have
up-to-date at loads/stores. So far on x86 guest that has not
mattered since indeed only the x87 FP registers and tags are
accessed using GetI/PutI, and there is no need so far for them to
be up to date at mem exception points. The rPutI pass should be
fixed.
TODO: improve pessimistic handling of precise exceptions
in the tree builder.
@@ -142,8 +151,7 @@
CSE up F64 literals (already doing F64is)
CSE: consider carefully the requirement for precise exns
prior to making CSE any more aggressive.
*/
prior to making CSE any more aggressive. */
/*---------------------------------------------------------------*/
@@ -726,7 +734,9 @@ static void handle_gets_Stmt (
(minoff,maxoff) to the set.
On seeing 'Get (minoff,maxoff)', remove any part of the set
overlapping (minoff,maxoff).
overlapping (minoff,maxoff). The same has to happen for any events
which implicitly read parts of the guest state: dirty helper calls
and loads/stores.
*/
static void redundant_put_removal_BB (
@@ -798,7 +808,9 @@ static void redundant_put_removal_BB (
/* Deal with Gets. These remove bits of the environment since
appearance of a Get means that the next event for that slice
of the guest state is no longer a write, but a read. */
of the guest state is no longer a write, but a read. Also
deals with implicit reads of guest state needed to maintain
precise exceptions. */
handle_gets_Stmt( env, st, preciseMemExnsFn );
}
}
@@ -1322,6 +1334,8 @@ static IRStmt* subst_and_fold_Stmt ( IRExpr** env, IRStmt* st )
/* Interesting. The condition on this exit has folded down to
a constant. */
vassert(fcond->Iex.Const.con->tag == Ico_U1);
vassert(fcond->Iex.Const.con->Ico.U1 == False
|| fcond->Iex.Const.con->Ico.U1 == True);
if (fcond->Iex.Const.con->Ico.U1 == False) {
/* exit is never going to happen, so dump the statement. */
return NULL;
@@ -3271,7 +3285,7 @@ static void dumpInvalidated ( TmpInfo** env, IRBB* bb, /*INOUT*/Int* j )
invPut = st->tag == Ist_Put
|| st->tag == Ist_PutI || st->tag == Ist_Dirty;
invStore = st->tag == Ist_STle
|| st->tag == Ist_Dirty;
|| st->tag == Ist_Dirty;
for (k = 0; k < n_tmps; k++) {
ti = env[k];