From 838e0db2a31fb0872a8b8db68b69f28cde4f4bf4 Mon Sep 17 00:00:00 2001 From: merrill Date: Fri, 3 Mar 1995 03:45:02 +0000 Subject: Update CLEANUP_POINT_EXPR docs. git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@9118 138bc75d-0d04-0410-961f-82ee72b054a4 --- gcc/tree.def | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) (limited to 'gcc/tree.def') diff --git a/gcc/tree.def b/gcc/tree.def index 1338a73b65a..453e2886482 100644 --- a/gcc/tree.def +++ b/gcc/tree.def @@ -444,8 +444,20 @@ DEFTREECODE (METHOD_CALL_EXPR, "method_call_expr", "e", 4) DEFTREECODE (WITH_CLEANUP_EXPR, "with_cleanup_expr", "e", 3) /* Specify a cleanup point. - Operand 0 is the expression that has cleanups that we want ensure are - cleaned up. */ + Operand 0 is an expression that may have cleanups. If it does, those + cleanups are executed after the expression is expanded. + + Note that if the expression is a reference to storage, it is forced out + of memory before the cleanups are run. This is necessary to handle + cases where the cleanups modify the storage referenced; in the + expression 't.i', if 't' is a struct with an integer member 'i' and a + cleanup which modifies 'i', the value of the expression depends on + whether the cleanup is run before or after 't.i' is evaluated. When + expand_expr is run on 't.i', it returns a MEM. This is not good enough; + the value of 't.i' must be forced out of memory. + + As a consequence, the operand of a CLEANUP_POINT_EXPR must not have + BLKmode, because it will not be forced out of memory. */ DEFTREECODE (CLEANUP_POINT_EXPR, "cleanup_point_expr", "e", 1) /* The following two codes are used in languages that have types where -- cgit v1.2.1