Hi!
The following testcase ICEs, because the PR84305 changes try to evaluate
the size earlier. If size has side-effects, that is desirable, and the
side-effects will actually be wrapped in a SAVE_EXPR. The problem on this
testcase is that there are no side-effects, and c_fully_fold doesn't fold
those COMPOUND_EXPRs to constant, and while before gimplification we unshare
trees found in the expressions, the unsharing doesn't involve TYPE_SIZE etc.
of used types. Gimplification is destructive though, so when we gimplify
the two nested COMPOUND_EXPRs and then try to gimplify it the second time
for the TYPE_SIZEs, we ICE.
Now, we could use unshare_expr in what we push to *expr, SAVE_EXPRs and
their operands in there aren't unshared, but I really don't see a point of
evaluating expressions that don't have side-effects before, so instead
this just pushes there expressions that do have side-effects.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk and
release branches?
2020-02-13 Jakub Jelinek <ja...@redhat.com>
PR c/93576
* c-decl.c (grokdeclarator): If this_size_varies, only push size into
*expr if it has side effects.
* gcc.dg/pr93576.c: New test.
--- gcc/c/c-decl.c.jj 2020-01-15 12:34:15.079253187 +0100
+++ gcc/c/c-decl.c 2020-02-13 13:49:06.427304070 +0100
@@ -6512,11 +6512,14 @@ grokdeclarator (const struct c_declarato
}
if (this_size_varies)
{
- if (*expr)
- *expr = build2 (COMPOUND_EXPR, TREE_TYPE (size),
- *expr, size);
- else
- *expr = size;
+ if (TREE_SIDE_EFFECTS (size))
+ {
+ if (*expr)
+ *expr = build2 (COMPOUND_EXPR, TREE_TYPE (size),
+ *expr, size);
+ else
+ *expr = size;
+ }
*expr_const_operands &= size_maybe_const;
}
}
--- gcc/testsuite/gcc.dg/pr93576.c.jj 2020-02-13 13:53:06.089708612 +0100
+++ gcc/testsuite/gcc.dg/pr93576.c 2020-02-13 13:52:40.041099237 +0100
@@ -0,0 +1,10 @@
+/* PR c/93576 */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+void
+foo (void)
+{
+ int b[] = { 0 };
+ (char (*)[(1, 7, 2)]) 0;
+}
Jakub
