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From: "aldyh at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/107561] New: g++.dg/pr17488.C regression due to -Wstringop-overflow problem Date: Mon, 07 Nov 2022 20:06:42 +0000 [thread overview] Message-ID: <bug-107561-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107561 Bug ID: 107561 Summary: g++.dg/pr17488.C regression due to -Wstringop-overflow problem Product: gcc Version: 12.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: aldyh at gcc dot gnu.org Target Milestone: --- g++.dg/pr17488.C fails after commit r13-3761 with: warning: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ writing 8 or more bytes into a region of size 0 overflows the destination [-Wstringop-overflow=] ... ... note: destination object of size 0 allocated by ‘operator new’ There is no difference in the IL the -Wstringop-overflow pass sees. For that matter, there is no difference in the entire IL across through the *.optimized dump. However, there are different ranges for two SSA names. In the *.waccess1 pass we see: --- /tmp/a.ii.025t.waccess1.orig.787460 2022-11-07 19:43:41.341855227 +0100 +++ /tmp/a.ii.025t.waccess1.new.787460 2022-11-07 19:43:41.344855238 +0100 @@ -331,8 +331,8 @@ max_depth: 3 pointer_query cache contents: - 5.0[1]: _5 = _5 (base0); size: unknown - 6.0[3]: _6 = _5 (base0); size: unknown + 5.0[1]: _5 = _5 (base0); size: [16, 9223372036854775807] + 6.0[3]: _6 = _5 (base0); size: [16, 9223372036854775807] __attribute__((malloc)) struct valarray * std::__valarray_get_storage<std::valarray<long long int> > (size_t __n) @@ -364,8 +364,8 @@ max_depth: 3 pointer_query cache contents: - 5.0[1]: _5 = _5 (base0); size: unknown - 6.0[3]: _6 = _5 (base0); size: unknown + 5.0[1]: _5 = _5 (base0); size: [8, 9223372036854775807] + 6.0[3]: _6 = _5 (base0); size: [8, 9223372036854775807] __attribute__((malloc)) long long int * std::__valarray_get_storage<long long int> (size_t __n) This coincides with two unsigned multiplications by 16 and 8, where we correctly restrict the range. This is from the evrp dump: -Global Exported: _2 = [irange] long unsigned int [0, +INF] NONZERO 0xfffffffffffffff0 +Global Exported: _2 = [irange] long unsigned int [0, 0][16, +INF] NONZERO 0xfffffffffffffff0 -Global Exported: _2 = [irange] long unsigned int [0, +INF] NONZERO 0xfffffffffffffff8 +Global Exported: _2 = [irange] long unsigned int [0, 0][8, +INF] NONZERO 0xfffffffffffffff8 This is correct as we know the ranges cannot be [1,15] and [1,7] respectively.
next reply other threads:[~2022-11-07 20:06 UTC|newest] Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-11-07 20:06 aldyh at gcc dot gnu.org [this message] 2022-11-07 20:10 ` [Bug tree-optimization/107561] [13 Regression] " pinskia at gcc dot gnu.org 2022-11-08 8:31 ` aldyh at gcc dot gnu.org 2022-11-08 8:48 ` [Bug tree-optimization/107561] [13 Regression] g++.dg/pr17488.C and [g++.dg/warn/Warray-bounds-16.C -m32] " aldyh at gcc dot gnu.org 2022-11-08 9:34 ` rguenth at gcc dot gnu.org 2022-11-08 13:43 ` aldyh at gcc dot gnu.org 2022-11-08 18:27 ` pinskia at gcc dot gnu.org 2022-12-14 15:43 ` [Bug tree-optimization/107561] [13 Regression] g++.dg/pr71488.C " danglin at gcc dot gnu.org 2023-01-13 12:42 ` rguenth at gcc dot gnu.org 2023-02-02 18:53 ` hp at gcc dot gnu.org 2023-02-02 21:03 ` hp at gcc dot gnu.org 2023-02-10 0:42 ` cvs-commit at gcc dot gnu.org 2023-02-27 9:56 ` rguenth at gcc dot gnu.org 2023-02-27 11:18 ` rguenth at gcc dot gnu.org 2023-02-27 12:49 ` rguenth at gcc dot gnu.org 2023-02-27 13:45 ` aldyh at gcc dot gnu.org 2023-02-27 14:38 ` redi at gcc dot gnu.org 2023-02-27 16:16 ` aldyh at gcc dot gnu.org 2023-03-01 14:22 ` rguenth at gcc dot gnu.org 2023-03-01 14:34 ` jakub at gcc dot gnu.org 2023-03-01 14:38 ` rguenth at gcc dot gnu.org 2023-03-01 14:55 ` jakub at gcc dot gnu.org 2023-03-01 14:57 ` jakub at gcc dot gnu.org 2023-03-01 15:55 ` redi at gcc dot gnu.org 2023-03-02 7:51 ` rguenth at gcc dot gnu.org 2023-03-02 7:53 ` rguenth at gcc dot gnu.org 2023-03-29 11:38 ` rguenth at gcc dot gnu.org 2023-03-29 11:41 ` rguenth at gcc dot gnu.org 2023-03-30 11:16 ` cvs-commit at gcc dot gnu.org 2023-03-30 11:17 ` rguenth at gcc dot gnu.org
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