e25dce5013
This fixes a long-standing issue in PRE where we track valueized expressions in our expression sets that we use for PHI translation, code insertion but also feed into match-and-simplify via vn_nary_simplify. But that's not what is expected from vn_nary_simplify or match-and-simplify which assume we are simplifying with operands available at the point of the expression so they can use contextual information on the SSA names like ranges. While the VN side was updated to ensure this with the rewrite to RPO VN, thereby removing all workarounds that nullified such contextual info on all SSA names, the PRE side still suffers from this. The following patch tries to apply minimal surgery at this point and makes PRE track un-valueized expressions in the expression sets but only for the NARY kind (both NAME and CONSTANT do not suffer from this issue), leaving the REFERENCE kind alone. The REFERENCE kind is important when trying to remove the workarounds still in place in compute_avail for code hoisting, but that's a separate issue and we have a working workaround in place. Doing this comes at the cost of duplicating the VN IL on the PRE side for NARY and eventually some extra overhead for translated expressions that is difficult to assess. 2022-02-25 Richard Biener <rguenther@suse.de> PR tree-optimization/103037 * tree-ssa-sccvn.h (alloc_vn_nary_op_noinit): Declare. (vn_nary_length_from_stmt): Likewise. (init_vn_nary_op_from_stmt): Likewise. (vn_nary_op_compute_hash): Likewise. * tree-ssa-sccvn.cc (alloc_vn_nary_op_noinit): Export. (vn_nary_length_from_stmt): Likewise. (init_vn_nary_op_from_stmt): Likewise. (vn_nary_op_compute_hash): Likewise. * tree-ssa-pre.cc (pre_expr_obstack): New obstack. (get_or_alloc_expr_for_nary): Pass in the value-id to use, (re-)compute the hash value and if the expression is not found allocate it from pre_expr_obstack. (phi_translate_1): Do not insert the NARY found in the VN tables but build a PRE expression from the valueized NARY with the value-id we eventually found. (find_or_generate_expression): Assert we have an entry for constant values. (compute_avail): Insert not valueized expressions into EXP_GEN using the value-id from the VN tables. (init_pre): Allocate pre_expr_obstack. (fini_pre): Free pre_expr_obstack. * gcc.dg/torture/pr103037.c: New testcase. |
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| c++tools | ||
| config | ||
| contrib | ||
| fixincludes | ||
| gcc | ||
| gnattools | ||
| gotools | ||
| include | ||
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| libffi | ||
| libgcc | ||
| libgfortran | ||
| libgo | ||
| libgomp | ||
| libiberty | ||
| libitm | ||
| libobjc | ||
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| libquadmath | ||
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| libstdc++-v3 | ||
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| lto-plugin | ||
| maintainer-scripts | ||
| zlib | ||
| .dir-locals.el | ||
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| ltmain.sh | ||
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