public inbox for gcc-cvs@sourceware.org help / color / mirror / Atom feed
From: Martin Jambor <jamborm@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r12-8564] tree-sra: Fix union handling in build_reconstructed_reference Date: Mon, 11 Jul 2022 16:47:39 +0000 (GMT) [thread overview] Message-ID: <20220711164739.2CAAB3858419@sourceware.org> (raw) https://gcc.gnu.org/g:1a78fffb3845f879e36ba33b4d15e75b3df8d5a7 commit r12-8564-g1a78fffb3845f879e36ba33b4d15e75b3df8d5a7 Author: Martin Jambor <mjambor@suse.cz> Date: Mon Jul 11 18:43:23 2022 +0200 tree-sra: Fix union handling in build_reconstructed_reference As the testcase in PR 105860 shows, the code that tries to re-use the handled_component chains in SRA can be horribly confused by unions, where it thinks it has found a compatible structure under which it can chain the references, but in fact it found the type it was looking for elsewhere in a union and generated a write to a completely wrong part of an aggregate. I don't remember whether the plan was to support unions at all in build_reconstructed_reference but it can work, to an extent, if we make sure that we start the search only outside the outermost union, which is what the patch does (and the extra testcase verifies). Additionally, this commit also contains sqashed in it a backport of b984b84cbe4bf026edef2ba37685f3958a1dc1cf which fixes the testcase gcc.dg/tree-ssa/alias-access-path-13.c for many 32-bit targets. gcc/ChangeLog: 2022-07-01 Martin Jambor <mjambor@suse.cz> PR tree-optimization/105860 * tree-sra.cc (build_reconstructed_reference): Start expr traversal only just below the outermost union. gcc/testsuite/ChangeLog: 2022-07-01 Martin Jambor <mjambor@suse.cz> PR tree-optimization/105860 * gcc.dg/tree-ssa/alias-access-path-13.c: New test. * gcc.dg/tree-ssa/pr105860.c: Likewise. (cherry picked from commit b110e5283e368b5377e04766e4ff82cd52634208) Diff: --- .../gcc.dg/tree-ssa/alias-access-path-13.c | 36 +++++++++++++ gcc/testsuite/gcc.dg/tree-ssa/pr105860.c | 63 ++++++++++++++++++++++ gcc/tree-sra.cc | 13 ++++- 3 files changed, 111 insertions(+), 1 deletion(-) diff --git a/gcc/testsuite/gcc.dg/tree-ssa/alias-access-path-13.c b/gcc/testsuite/gcc.dg/tree-ssa/alias-access-path-13.c new file mode 100644 index 00000000000..87a94f5bf31 --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/alias-access-path-13.c @@ -0,0 +1,36 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-fre1" } */ + +struct inn +{ + int val; +}; + +struct biggerstruct +{ + int a, b; +}; + +union foo +{ + struct inn inn; + struct biggerstruct baz; +} *fooptr; + +struct bar +{ + union foo foo; + int val2; +} *barptr; + +int +test () +{ + union foo foo; + foo.inn.val = 0; + barptr->val2 = 123; + *fooptr = foo; + return barptr->val2; +} + +/* { dg-final { scan-tree-dump-times "return 123" 1 "fre1"} } */ diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr105860.c b/gcc/testsuite/gcc.dg/tree-ssa/pr105860.c new file mode 100644 index 00000000000..77bcb4a6739 --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr105860.c @@ -0,0 +1,63 @@ +/* { dg-do run } */ +/* { dg-options "-O1" } */ + +struct S1 { + unsigned int _0; + unsigned int _1; +} ; +struct S2 { + struct S1 _s1; + unsigned long _x2; +} ; + +struct ufld_type1 { + unsigned int _u1t; + struct S2 _s2; +} ; + +struct ufld_type2 { + unsigned int _u2t; + struct S1 _s1; +} ; +struct parm_type { + union { + struct ufld_type1 var_1; + struct ufld_type2 var_2; + } U; +}; + +struct parm_type bad_function( struct parm_type arg0 ) +{ + struct parm_type rv; + struct S2 var4; + switch( arg0.U.var_2._u2t ) { + case 4294967041: + var4._s1 = arg0.U.var_1._s2._s1; + rv.U.var_1._u1t = 4294967041; + rv.U.var_1._s2 = var4; + break; + case 4294967043: + rv.U.var_2._u2t = 4294967043; + rv.U.var_2._s1 = arg0.U.var_2._s1; + break; + default: + break; + } + return rv; +} + +int main() { + struct parm_type val; + struct parm_type out; + val.U.var_2._u2t = 4294967043; + val.U.var_2._s1._0 = 0x01010101; + val.U.var_2._s1._1 = 0x02020202; + out = bad_function(val); + if (val.U.var_2._u2t != 4294967043) + __builtin_abort (); + if (out.U.var_2._s1._0 != 0x01010101) + __builtin_abort (); + if (val.U.var_2._s1._1 != 0x02020202 ) + __builtin_abort (); + return 0; +} diff --git a/gcc/tree-sra.cc b/gcc/tree-sra.cc index 081c51b58a4..099e8dbe873 100644 --- a/gcc/tree-sra.cc +++ b/gcc/tree-sra.cc @@ -1667,7 +1667,18 @@ build_ref_for_offset (location_t loc, tree base, poly_int64 offset, static tree build_reconstructed_reference (location_t, tree base, struct access *model) { - tree expr = model->expr, prev_expr = NULL; + tree expr = model->expr; + /* We have to make sure to start just below the outermost union. */ + tree start_expr = expr; + while (handled_component_p (expr)) + { + if (TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0))) == UNION_TYPE) + start_expr = expr; + expr = TREE_OPERAND (expr, 0); + } + + expr = start_expr; + tree prev_expr = NULL_TREE; while (!types_compatible_p (TREE_TYPE (expr), TREE_TYPE (base))) { if (!handled_component_p (expr))
reply other threads:[~2022-07-11 16:47 UTC|newest] Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20220711164739.2CAAB3858419@sourceware.org \ --to=jamborm@gcc.gnu.org \ --cc=gcc-cvs@gcc.gnu.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).