From d74641bdd752306ad41b4cd3b2f747ec046cb391 Mon Sep 17 00:00:00 2001 From: Richard Sandiford Date: Tue, 13 Feb 2018 10:28:54 +0000 Subject: [PATCH] Add a DECL_EXPR for VLA pointer casts (PR 84305) This PR was about a case in which we ended up with a MULT_EXPR that was shared between an ungimplified VLA type and a pointer calculation. The SSA names used in the pointer calculation were later freed, but they were still there in the VLA, and caused an ICE when remapping the types during inlinling. The fix is to add a DECL_EXPR that forces the VLA type sizes to be gimplified too, but the tricky part is deciding where. As the comment in grokdeclarator says, we can't just add it to the statement list, since the size might only be conditionally evaluated. It might also end up being evaluated out of sequence. The patch gets around that by putting the DECL_EXPR in a BIND_EXPR and adding the BIND_EXPR to the list of things that need to be evaluated for the declarator. 2018-02-13 Richard Sandiford gcc/c/ PR c/84305 * c-decl.c (grokdeclarator): Create an anonymous TYPE_DECL in PARM and TYPENAME contexts too, but attach it to a BIND_EXPR and include the BIND_EXPR in the list of things that need to be pre-evaluated. gcc/testsuite/ PR c/84305 * gcc.c-torture/compile/pr84305.c: New test. From-SVN: r257620 --- gcc/c/ChangeLog | 8 +++ gcc/c/c-decl.c | 53 ++++++++++++++----- gcc/testsuite/ChangeLog | 5 ++ gcc/testsuite/gcc.c-torture/compile/pr84305.c | 4 ++ 4 files changed, 56 insertions(+), 14 deletions(-) create mode 100644 gcc/testsuite/gcc.c-torture/compile/pr84305.c diff --git a/gcc/c/ChangeLog b/gcc/c/ChangeLog index bca7268c118..f0fd33e9790 100644 --- a/gcc/c/ChangeLog +++ b/gcc/c/ChangeLog @@ -1,3 +1,11 @@ +2018-02-13 Richard Sandiford + + PR c/84305 + * c-decl.c (grokdeclarator): Create an anonymous TYPE_DECL + in PARM and TYPENAME contexts too, but attach it to a BIND_EXPR + and include the BIND_EXPR in the list of things that need to be + pre-evaluated. + 2018-02-09 Nathan Sidwell PR c/84293 diff --git a/gcc/c/c-decl.c b/gcc/c/c-decl.c index f8004649a35..f0198ec81c3 100644 --- a/gcc/c/c-decl.c +++ b/gcc/c/c-decl.c @@ -6479,28 +6479,53 @@ grokdeclarator (const struct c_declarator *declarator, type has a name/declaration of it's own, but special attention is required if the type is anonymous. - We handle the NORMAL and FIELD contexts here by attaching an - artificial TYPE_DECL to such pointed-to type. This forces the - sizes evaluation at a safe point and ensures it is not deferred - until e.g. within a deeper conditional context. - - We expect nothing to be needed here for PARM or TYPENAME. - Pushing a TYPE_DECL at this point for TYPENAME would actually - be incorrect, as we might be in the middle of an expression - with side effects on the pointed-to type size "arguments" prior - to the pointer declaration point and the fake TYPE_DECL in the - enclosing context would force the size evaluation prior to the - side effects. */ - + We attach an artificial TYPE_DECL to such pointed-to type + and arrange for it to be included in a DECL_EXPR. This + forces the sizes evaluation at a safe point and ensures it + is not deferred until e.g. within a deeper conditional context. + + PARM contexts have no enclosing statement list that + can hold the DECL_EXPR, so we need to use a BIND_EXPR + instead, and add it to the list of expressions that + need to be evaluated. + + TYPENAME contexts do have an enclosing statement list, + but it would be incorrect to use it, as the size should + only be evaluated if the containing expression is + evaluated. We might also be in the middle of an + expression with side effects on the pointed-to type size + "arguments" prior to the pointer declaration point and + the fake TYPE_DECL in the enclosing context would force + the size evaluation prior to the side effects. We therefore + use BIND_EXPRs in TYPENAME contexts too. */ if (!TYPE_NAME (type) - && (decl_context == NORMAL || decl_context == FIELD) && variably_modified_type_p (type, NULL_TREE)) { + tree bind = NULL_TREE; + if (decl_context == TYPENAME || decl_context == PARM) + { + bind = build3 (BIND_EXPR, void_type_node, NULL_TREE, + NULL_TREE, NULL_TREE); + TREE_SIDE_EFFECTS (bind) = 1; + BIND_EXPR_BODY (bind) = push_stmt_list (); + push_scope (); + } tree decl = build_decl (loc, TYPE_DECL, NULL_TREE, type); DECL_ARTIFICIAL (decl) = 1; pushdecl (decl); finish_decl (decl, loc, NULL_TREE, NULL_TREE, NULL_TREE); TYPE_NAME (type) = decl; + if (bind) + { + pop_scope (); + BIND_EXPR_BODY (bind) + = pop_stmt_list (BIND_EXPR_BODY (bind)); + if (*expr) + *expr = build2 (COMPOUND_EXPR, void_type_node, *expr, + bind); + else + *expr = bind; + } } type = c_build_pointer_type (type); diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 878a78e299e..42bd190a872 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2018-02-13 Richard Sandiford + + PR c/84305 + * gcc.c-torture/compile/pr84305.c: New test. + 2018-02-13 Jakub Jelinek PR target/84335 diff --git a/gcc/testsuite/gcc.c-torture/compile/pr84305.c b/gcc/testsuite/gcc.c-torture/compile/pr84305.c new file mode 100644 index 00000000000..374fa67f593 --- /dev/null +++ b/gcc/testsuite/gcc.c-torture/compile/pr84305.c @@ -0,0 +1,4 @@ +int res, a, b; +void *foo; +static void f2 (int arg) { res = ((int (*)[arg][b]) foo)[0][0][0]; } +void f1 (void) { f2 (a); } -- 2.30.2