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[Bug tree-optimization/86532] [9 Regression] Wrong code due to a wrong strlen folding starting with r262522
- From: "msebor at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Tue, 17 Jul 2018 15:41:17 +0000
- Subject: [Bug tree-optimization/86532] [9 Regression] Wrong code due to a wrong strlen folding starting with r262522
- Auto-submitted: auto-generated
- References: <bug-86532-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86532
--- Comment #13 from Martin Sebor <msebor at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #9)
>
> I bet Martin would argue it's invalid ...
That's right, the example in comment 8 is undefined because strlen() requires a
nul-terminated string argument and a[0] in the call strlen(a[0]) is not such a
string. It's not valid for strlen() to access one subobject when passed a
pointer to another, even if the two are adjacent in memory. This applies
equally to struct members as well as multidimensional arrays.