From e4837aa9fbb91803585f038de67b0d62d256b654 Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Wed, 1 Aug 2018 12:03:29 +0000 Subject: [PATCH] tree-ssa-sccvn.c (visit_phi): Compare invariant addresses as base and offset. 2018-08-01 Richard Biener * tree-ssa-sccvn.c (visit_phi): Compare invariant addresses as base and offset. * gcc.dg/tree-ssa/ssa-fre-68.c: New testcase. From-SVN: r263206 --- gcc/ChangeLog | 5 ++++ gcc/testsuite/ChangeLog | 4 ++++ gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-68.c | 28 ++++++++++++++++++++++ gcc/tree-ssa-sccvn.c | 19 +++++++++++++++ 4 files changed, 56 insertions(+) create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-68.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 477b245f146..0d10e950e23 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2018-08-01 Richard Biener + + * tree-ssa-sccvn.c (visit_phi): Compare invariant addresses + as base and offset. + 2018-08-01 Martin Liska * value-prof.c (gimple_divmod_fixed_value_transform): Unify diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 0743b9593aa..7fcc05da6a9 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2018-08-01 Richard Biener + + * gcc.dg/tree-ssa/ssa-fre-68.c: New testcase. + 2018-08-01 Uros Bizjak * gcc.dg/plugin/poly-int-07_plugin.c (dg-options): Use -O0. diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-68.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-68.c new file mode 100644 index 00000000000..d9f07bd59ba --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-68.c @@ -0,0 +1,28 @@ +/* { dg-do compile } */ +/* { dg-options "-O -fdump-tree-fre1" } */ + +struct S { char a[3]; char b[5]; } s = { "abc", "defg" }; + +__SIZE_TYPE__ +foo (struct S s, int a, int b) +{ + char *p = (char *) &s.a[0]; + if (a) + p = (char *) &s.a; + else if (b) + p = (char *) &s; + return __builtin_strlen (p); +} + +__SIZE_TYPE__ +bar (int a, int b) +{ + char *p = (char *) &s.a[0]; + if (a) + p = (char *) &s.a; + else if (b) + p = (char *) &s; + return __builtin_strlen (p); +} + +/* { dg-final { scan-tree-dump-times "strlen \\\(&s" 2 "fre1" } } */ diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c index 833291a57a6..43f3313911f 100644 --- a/gcc/tree-ssa-sccvn.c +++ b/gcc/tree-ssa-sccvn.c @@ -3941,6 +3941,8 @@ static bool visit_phi (gimple *phi) { tree result, sameval = VN_TOP, seen_undef = NULL_TREE; + tree sameval_base = NULL_TREE; + poly_int64 soff, doff; unsigned n_executable = 0; bool allsame = true; edge_iterator ei; @@ -3971,6 +3973,23 @@ visit_phi (gimple *phi) sameval = def; else if (!expressions_equal_p (def, sameval)) { + /* We know we're arriving only with invariant addresses here, + try harder comparing them. We can do some caching here + which we cannot do in expressions_equal_p. */ + if (TREE_CODE (def) == ADDR_EXPR + && TREE_CODE (sameval) == ADDR_EXPR + && sameval_base != (void *)-1) + { + if (!sameval_base) + sameval_base = get_addr_base_and_unit_offset + (TREE_OPERAND (sameval, 0), &soff); + if (!sameval_base) + sameval_base = (tree)(void *)-1; + else if ((get_addr_base_and_unit_offset + (TREE_OPERAND (def, 0), &doff) == sameval_base) + && known_eq (soff, doff)) + continue; + } allsame = false; break; } -- 2.30.2