From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1666) id D29203851C07; Thu, 5 May 2022 12:41:40 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org D29203851C07 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Richard Biener To: gcc-cvs@gcc.gnu.org Subject: [gcc r13-137] tree-optimization/104162 - CSE of &MEM[ptr].a[i] and ptr + CST X-Act-Checkin: gcc X-Git-Author: Richard Biener X-Git-Refname: refs/heads/master X-Git-Oldrev: 92fff39f06449f907d8781a5dcaad0e8b9743480 X-Git-Newrev: ee1cb43bc76de800efa0ade687b0cd28e62a5f82 Message-Id: <20220505124140.D29203851C07@sourceware.org> Date: Thu, 5 May 2022 12:41:40 +0000 (GMT) X-BeenThere: gcc-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 05 May 2022 12:41:40 -0000 https://gcc.gnu.org/g:ee1cb43bc76de800efa0ade687b0cd28e62a5f82 commit r13-137-gee1cb43bc76de800efa0ade687b0cd28e62a5f82 Author: Richard Biener Date: Wed Jan 26 15:34:54 2022 +0100 tree-optimization/104162 - CSE of &MEM[ptr].a[i] and ptr + CST This adds the capability to value-numbering of treating complex address expressions where the offset becomes invariant as equal to a POINTER_PLUS_EXPR. This restores CSE that is now prevented by early lowering of &MEM[ptr + CST] to a POINTER_PLUS_EXPR. Unfortunately this regresses gcc.dg/asan/pr99673.c again, so the testcase is adjusted accordingly. 2022-01-26 Richard Biener PR tree-optimization/104162 * tree-ssa-sccvn.cc (vn_reference_lookup): Handle &MEM[_1 + 5].a[i] like a POINTER_PLUS_EXPR if the offset becomes invariant. (vn_reference_insert): Likewise. * gcc.dg/tree-ssa/ssa-fre-99.c: New testcase. * gcc.dg/asan/pr99673.c: Adjust. Diff: --- gcc/testsuite/gcc.dg/asan/pr99673.c | 4 +- gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-99.c | 27 ++++++++++++ gcc/tree-ssa-sccvn.cc | 66 +++++++++++++++++++++++++++++- 3 files changed, 95 insertions(+), 2 deletions(-) diff --git a/gcc/testsuite/gcc.dg/asan/pr99673.c b/gcc/testsuite/gcc.dg/asan/pr99673.c index 05857fd46c7..a1e9631af2e 100644 --- a/gcc/testsuite/gcc.dg/asan/pr99673.c +++ b/gcc/testsuite/gcc.dg/asan/pr99673.c @@ -1,4 +1,6 @@ /* { dg-do compile } */ +/* Skip XPASS cases. */ +/* { dg-skip-if "" { *-*-* } { "-O0" "-O1" "-O2 -flto" } { "" } } */ /* { dg-additional-options "-Wstringop-overread" } */ struct B { @@ -22,6 +24,6 @@ void g (struct C *pc, struct D *pd, int i) pd->i = pb->i; const short *psa = pb->a[i].sa; - if (f (psa)) + if (f (psa)) /* { dg-bogus "from a region of size" "pr99673" { xfail *-*-* } } */ return; } diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-99.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-99.c new file mode 100644 index 00000000000..101d0d63f7a --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-99.c @@ -0,0 +1,27 @@ +/* { dg-do compile } */ +/* Disable FRE1 because that for the sake of __builtin_object_size + will not consider the equality but still valueize 'i', defeating + the purpose of the check. */ +/* { dg-options "-O -fdump-tree-fre3 -fdisable-tree-fre1" } */ + +struct S { int a[4]; }; + +int i; +int bar (struct S *p) +{ + char *q = (char *)p + 4; + i = 1; + int *r = &((struct S *)p)->a[i]; + return q == (char *)r; +} +int baz (struct S *p) +{ + i = 1; + int *r = &((struct S *)p)->a[i]; + char *q = (char *)p + 4; + return q == (char *)r; +} + +/* Verify FRE can handle valueizing &p->a[i] and value-numbering it + equal to a POINTER_PLUS_EXPR. */ +/* { dg-final { scan-tree-dump-times "return 1;" 2 "fre3" } } */ diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc index 3c90c1e23e6..76587632312 100644 --- a/gcc/tree-ssa-sccvn.cc +++ b/gcc/tree-ssa-sccvn.cc @@ -3666,6 +3666,38 @@ vn_reference_lookup (tree op, tree vuse, vn_lookup_kind kind, vr1.vuse = vuse_ssa_val (vuse); vr1.operands = operands = valueize_shared_reference_ops_from_ref (op, &valueized_anything); + + /* Handle &MEM[ptr + 5].b[1].c as POINTER_PLUS_EXPR. Avoid doing + this before the pass folding __builtin_object_size had a chance to run. */ + if ((cfun->curr_properties & PROP_objsz) + && operands[0].opcode == ADDR_EXPR + && operands.last ().opcode == SSA_NAME) + { + poly_int64 off = 0; + vn_reference_op_t vro; + unsigned i; + for (i = 1; operands.iterate (i, &vro); ++i) + { + if (vro->opcode == SSA_NAME) + break; + else if (known_eq (vro->off, -1)) + break; + off += vro->off; + } + if (i == operands.length () - 1) + { + gcc_assert (operands[i-1].opcode == MEM_REF); + tree ops[2]; + ops[0] = operands[i].op0; + ops[1] = wide_int_to_tree (sizetype, off); + tree res = vn_nary_op_lookup_pieces (2, POINTER_PLUS_EXPR, + TREE_TYPE (op), ops, NULL); + if (res) + return res; + return NULL_TREE; + } + } + vr1.type = TREE_TYPE (op); ao_ref op_ref; ao_ref_init (&op_ref, op); @@ -3757,13 +3789,45 @@ vn_reference_insert (tree op, tree result, tree vuse, tree vdef) vn_reference_t vr1; bool tem; + vec operands + = valueize_shared_reference_ops_from_ref (op, &tem); + /* Handle &MEM[ptr + 5].b[1].c as POINTER_PLUS_EXPR. Avoid doing this + before the pass folding __builtin_object_size had a chance to run. */ + if ((cfun->curr_properties & PROP_objsz) + && operands[0].opcode == ADDR_EXPR + && operands.last ().opcode == SSA_NAME) + { + poly_int64 off = 0; + vn_reference_op_t vro; + unsigned i; + for (i = 1; operands.iterate (i, &vro); ++i) + { + if (vro->opcode == SSA_NAME) + break; + else if (known_eq (vro->off, -1)) + break; + off += vro->off; + } + if (i == operands.length () - 1) + { + gcc_assert (operands[i-1].opcode == MEM_REF); + tree ops[2]; + ops[0] = operands[i].op0; + ops[1] = wide_int_to_tree (sizetype, off); + vn_nary_op_insert_pieces (2, POINTER_PLUS_EXPR, + TREE_TYPE (op), ops, result, + VN_INFO (result)->value_id); + return; + } + } + vr1 = XOBNEW (&vn_tables_obstack, vn_reference_s); if (TREE_CODE (result) == SSA_NAME) vr1->value_id = VN_INFO (result)->value_id; else vr1->value_id = get_or_alloc_constant_value_id (result); vr1->vuse = vuse_ssa_val (vuse); - vr1->operands = valueize_shared_reference_ops_from_ref (op, &tem).copy (); + vr1->operands = operands.copy (); vr1->type = TREE_TYPE (op); vr1->punned = false; ao_ref op_ref;