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| author | Richard Biener <rguenther@suse.de> | 2017-06-19 15:01:13 +0000 |
|---|---|---|
| committer | Richard Biener <rguenth@gcc.gnu.org> | 2017-06-19 15:01:13 +0000 |
| commit | 343ae898b17490d15c98f711ffcb04c88cca9235 (patch) | |
| tree | ef6963983505b5fc27f730d9f530a778279acca3 /gcc/tree-ssa-sccvn.c | |
| parent | 9787269815559a63fbbda58b35137f832a612984 (diff) | |
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re PR bootstrap/80887 (gnat bootstrap fails at s-regpat.o: raised STORAGE_ERROR : stack overflow or erroneous memory access)
2017-06-19 Richard Biener <rguenther@suse.de>
PR tree-optimization/80887
c/
* gimple-parser.c (c_parser_gimple_postfix_expression): Handle
negated _Literals to parse _Literal (int) -1.
* tree-ssa-sccvn.c (mprts_hook_cnt): New global.
(vn_lookup_simplify_result): Allow only mprts_hook_cnt succesful
simplified lookups, then reset mprts_hook.
(vn_nary_build_or_lookup_1): Set mprts_hook_cnt to 9 before
simplifying.
(try_to_simplify): Likewise.
* gcc.dg/tree-ssa/pr80887.c: New testcase.
From-SVN: r249373
Diffstat (limited to 'gcc/tree-ssa-sccvn.c')
| -rw-r--r-- | gcc/tree-ssa-sccvn.c | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c index 419da47..324cd73 100644 --- a/gcc/tree-ssa-sccvn.c +++ b/gcc/tree-ssa-sccvn.c @@ -1639,6 +1639,7 @@ vn_reference_lookup_or_insert_for_pieces (tree vuse, } static vn_nary_op_t vn_nary_op_insert_stmt (gimple *stmt, tree result); +static unsigned mprts_hook_cnt; /* Hook for maybe_push_res_to_seq, lookup the expression in the VN tables. */ @@ -1648,8 +1649,22 @@ vn_lookup_simplify_result (code_helper rcode, tree type, tree *ops) if (!rcode.is_tree_code ()) return NULL_TREE; vn_nary_op_t vnresult = NULL; - return vn_nary_op_lookup_pieces (TREE_CODE_LENGTH ((tree_code) rcode), - (tree_code) rcode, type, ops, &vnresult); + tree res = vn_nary_op_lookup_pieces (TREE_CODE_LENGTH ((tree_code) rcode), + (tree_code) rcode, type, ops, &vnresult); + /* We can end up endlessly recursing simplifications if the lookup above + presents us with a def-use chain that mirrors the original simplification. + See PR80887 for an example. Limit successful lookup artificially + to 10 times if we are called as mprts_hook. */ + if (res + && mprts_hook + && --mprts_hook_cnt == 0) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Resetting mprts_hook after too many " + "invocations.\n"); + mprts_hook = NULL; + } + return res; } /* Return a value-number for RCODE OPS... either by looking up an existing @@ -1666,6 +1681,7 @@ vn_nary_build_or_lookup_1 (code_helper rcode, tree type, tree *ops, So first simplify and lookup this expression to see if it is already available. */ mprts_hook = vn_lookup_simplify_result; + mprts_hook_cnt = 9; bool res = false; switch (TREE_CODE_LENGTH ((tree_code) rcode)) { @@ -3896,6 +3912,7 @@ try_to_simplify (gassign *stmt) /* First try constant folding based on our current lattice. */ mprts_hook = vn_lookup_simplify_result; + mprts_hook_cnt = 9; tem = gimple_fold_stmt_to_constant_1 (stmt, vn_valueize, vn_valueize); mprts_hook = NULL; if (tem |