diff options
| author | Richard Biener <rguenther@suse.de> | 2022-06-30 10:33:40 +0200 |
|---|---|---|
| committer | Richard Biener <rguenther@suse.de> | 2022-07-01 08:51:59 +0200 |
| commit | 9701432ff79926a5dd3303be3417e0bd0c24140b (patch) | |
| tree | 28ebb1dfc448666ad234dc98d576fd5d3f7b0444 | |
| parent | 618bac5b486832edd3f8eb3ada74740e389dfcb8 (diff) | |
| download | gcc-9701432ff79926a5dd3303be3417e0bd0c24140b.zip gcc-9701432ff79926a5dd3303be3417e0bd0c24140b.tar.gz gcc-9701432ff79926a5dd3303be3417e0bd0c24140b.tar.bz2 | |
tree-optimization/106131 - wrong code with FRE rewriting
The following makes sure to not use the original TBAA type for
looking up a value across an aggregate copy when we had to offset
the read.
2022-06-30 Richard Biener <rguenther@suse.de>
PR tree-optimization/106131
* tree-ssa-sccvn.cc (vn_reference_lookup_3): Force alias-set
zero when offsetting the read looking through an aggregate
copy.
* g++.dg/torture/pr106131.C: New testcase.
| -rw-r--r-- | gcc/testsuite/g++.dg/torture/pr106131.C | 34 | ||||
| -rw-r--r-- | gcc/tree-ssa-sccvn.cc | 16 |
2 files changed, 46 insertions, 4 deletions
diff --git a/gcc/testsuite/g++.dg/torture/pr106131.C b/gcc/testsuite/g++.dg/torture/pr106131.C new file mode 100644 index 0000000..e110f4a --- /dev/null +++ b/gcc/testsuite/g++.dg/torture/pr106131.C @@ -0,0 +1,34 @@ +// { dg-do run { target c++11 } } + +struct Pair { + int a, b; + Pair(const Pair &) = default; + Pair(int _a, int _b) : a(_a), b(_b) {} + Pair &operator=(const Pair &z) { + a = z.a; + b = z.b; + return *this; + } +}; + +const int &max(const int &a, const int &b) +{ + return a < b ? b : a; +} + +int foo(Pair x, Pair y) +{ + return max(x.b, y.b); +} + +int main() +{ + auto f = new Pair[3] {{0, -11}, {0, -8}, {0, 2}}; + for (int i = 0; i < 1; i++) { + f[i] = f[0]; + if(i == 0) + f[i] = f[2]; + if (foo(f[i], f[1]) != 2) + __builtin_abort(); + } +} diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc index 9deedea..76d9289 100644 --- a/gcc/tree-ssa-sccvn.cc +++ b/gcc/tree-ssa-sccvn.cc @@ -3243,12 +3243,12 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_, poly_int64 extra_off = 0; if (j == 0 && i >= 0 && lhs_ops[0].opcode == MEM_REF - && maybe_ne (lhs_ops[0].off, -1)) + && known_ne (lhs_ops[0].off, -1)) { if (known_eq (lhs_ops[0].off, vr->operands[i].off)) i--, j--; else if (vr->operands[i].opcode == MEM_REF - && maybe_ne (vr->operands[i].off, -1)) + && known_ne (vr->operands[i].off, -1)) { extra_off = vr->operands[i].off - lhs_ops[0].off; i--, j--; @@ -3275,6 +3275,7 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_, copy_reference_ops_from_ref (rhs1, &rhs); /* Apply an extra offset to the inner MEM_REF of the RHS. */ + bool force_no_tbaa = false; if (maybe_ne (extra_off, 0)) { if (rhs.length () < 2) @@ -3287,6 +3288,10 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_, rhs[ix].op0 = int_const_binop (PLUS_EXPR, rhs[ix].op0, build_int_cst (TREE_TYPE (rhs[ix].op0), extra_off)); + /* When we have offsetted the RHS, reading only parts of it, + we can no longer use the original TBAA type, force alias-set + zero. */ + force_no_tbaa = true; } /* Save the operands since we need to use the original ones for @@ -3339,8 +3344,11 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_, /* Adjust *ref from the new operands. */ ao_ref rhs1_ref; ao_ref_init (&rhs1_ref, rhs1); - if (!ao_ref_init_from_vn_reference (&r, ao_ref_alias_set (&rhs1_ref), - ao_ref_base_alias_set (&rhs1_ref), + if (!ao_ref_init_from_vn_reference (&r, + force_no_tbaa ? 0 + : ao_ref_alias_set (&rhs1_ref), + force_no_tbaa ? 0 + : ao_ref_base_alias_set (&rhs1_ref), vr->type, vr->operands)) return (void *)-1; /* This can happen with bitfields. */ |