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| author | Jakub Jelinek <jakub@redhat.com> | 2017-07-17 11:10:23 +0200 |
|---|---|---|
| committer | Jakub Jelinek <jakub@gcc.gnu.org> | 2017-07-17 11:10:23 +0200 |
| commit | e8dd1313132e5aaa4c66b0bd2135919707dc45b6 (patch) | |
| tree | ab28fd58473d7498affb0856f0fba16c2c508561 /gcc/tree-ssa-phiprop.c | |
| parent | 764eec6cf591fcfe9bd0fe7760ecb657cfa6abc0 (diff) | |
| download | gcc-e8dd1313132e5aaa4c66b0bd2135919707dc45b6.zip gcc-e8dd1313132e5aaa4c66b0bd2135919707dc45b6.tar.gz gcc-e8dd1313132e5aaa4c66b0bd2135919707dc45b6.tar.bz2 | |
re PR tree-optimization/81365 (GCC miscompiles swap)
PR tree-optimization/81365
* tree-ssa-phiprop.c (propagate_with_phi): When considering hoisting
aggregate moves onto bb predecessor edges, make sure there are no
loads that could alias the lhs in between the start of bb and the
loads from *phi.
* g++.dg/torture/pr81365.C: New test.
From-SVN: r250261
Diffstat (limited to 'gcc/tree-ssa-phiprop.c')
| -rw-r--r-- | gcc/tree-ssa-phiprop.c | 27 |
1 files changed, 26 insertions, 1 deletions
diff --git a/gcc/tree-ssa-phiprop.c b/gcc/tree-ssa-phiprop.c index 8f8c133..7dcb9ee 100644 --- a/gcc/tree-ssa-phiprop.c +++ b/gcc/tree-ssa-phiprop.c @@ -327,7 +327,7 @@ propagate_with_phi (basic_block bb, gphi *phi, struct phiprop_d *phivn, if (!dominated_by_p (CDI_POST_DOMINATORS, bb, gimple_bb (use_stmt))) continue; - + /* Check whether this is a load of *ptr. */ if (!(is_gimple_assign (use_stmt) && gimple_assign_rhs_code (use_stmt) == MEM_REF @@ -356,6 +356,9 @@ propagate_with_phi (basic_block bb, gphi *phi, struct phiprop_d *phivn, insert aggregate copies on the edges instead. */ if (!is_gimple_reg_type (TREE_TYPE (TREE_TYPE (ptr)))) { + if (!gimple_vdef (use_stmt)) + goto next; + /* As we replicate the lhs on each incoming edge all used SSA names have to be available there. */ if (! for_each_index (gimple_assign_lhs_ptr (use_stmt), @@ -363,6 +366,28 @@ propagate_with_phi (basic_block bb, gphi *phi, struct phiprop_d *phivn, get_immediate_dominator (CDI_DOMINATORS, gimple_bb (phi)))) goto next; + + gimple *vuse_stmt; + imm_use_iterator vui; + use_operand_p vuse_p; + /* In order to move the aggregate copies earlier, make sure + there are no statements that could read from memory + aliasing the lhs in between the start of bb and use_stmt. + As we require use_stmt to have a VDEF above, loads after + use_stmt will use a different virtual SSA_NAME. */ + FOR_EACH_IMM_USE_FAST (vuse_p, vui, vuse) + { + vuse_stmt = USE_STMT (vuse_p); + if (vuse_stmt == use_stmt) + continue; + if (!dominated_by_p (CDI_DOMINATORS, + gimple_bb (vuse_stmt), bb)) + continue; + if (ref_maybe_used_by_stmt_p (vuse_stmt, + gimple_assign_lhs (use_stmt))) + goto next; + } + phiprop_insert_phi (bb, phi, use_stmt, phivn, n); /* Remove old stmt. The phi is taken care of by DCE. */ |