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| author | Richard Biener <rguenther@suse.de> | 2024-04-03 14:53:30 +0200 |
|---|---|---|
| committer | Richard Biener <rguenther@suse.de> | 2024-04-04 09:00:06 +0200 |
| commit | e152177b362143465e2b9d721ea632cae3f13445 (patch) | |
| tree | 961dfefa1e24808b7ce3a1b81a4cdcc28dfb91f9 /gcc | |
| parent | fe385c219994f6d5c1ffe00bcaf5a62c3d18caaf (diff) | |
| download | gcc-e152177b362143465e2b9d721ea632cae3f13445.zip gcc-e152177b362143465e2b9d721ea632cae3f13445.tar.gz gcc-e152177b362143465e2b9d721ea632cae3f13445.tar.bz2 | |
tree-optimization/114551 - loop splitting and undefined overflow
When loop splitting hoists a guard computation it needs to make sure
that can be safely evaluated at this place when it was previously
only conditionally evaluated. The following fixes this for the
case of undefined overflow.
PR tree-optimization/114551
* tree-ssa-loop-split.cc (split_loop): If the guard is
only conditionally evaluated rewrite computations with
possibly undefined overflow to unsigned arithmetic.
* gcc.dg/torture/pr114551.c: New testcase.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/testsuite/gcc.dg/torture/pr114551.c | 18 | ||||
| -rw-r--r-- | gcc/tree-ssa-loop-split.cc | 22 |
2 files changed, 38 insertions, 2 deletions
diff --git a/gcc/testsuite/gcc.dg/torture/pr114551.c b/gcc/testsuite/gcc.dg/torture/pr114551.c new file mode 100644 index 0000000..13c15fb --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr114551.c @@ -0,0 +1,18 @@ +/* { dg-do run } */ + +int a, b[4], c, d, e, f; +int main() +{ + a--; + for (f = 3; f >= 0; f--) + { + for (e = 0; e < 4; e++) + c = 0; + for (; c < 4; c++) + { + d = f && a > 0 && f > (2147483647 - a) ? 0 : b[f]; + continue; + } + } + return 0; +} diff --git a/gcc/tree-ssa-loop-split.cc b/gcc/tree-ssa-loop-split.cc index c0bb1b7..a770ea3 100644 --- a/gcc/tree-ssa-loop-split.cc +++ b/gcc/tree-ssa-loop-split.cc @@ -653,8 +653,26 @@ split_loop (class loop *loop1) gimple_seq stmts2; border = force_gimple_operand (border, &stmts2, true, NULL_TREE); if (stmts2) - gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop1), - stmts2); + { + /* When the split condition is not always evaluated make sure + to rewrite it to defined overflow. */ + if (!dominated_by_p (CDI_DOMINATORS, exit1->src, bbs[i])) + { + gimple_stmt_iterator gsi; + gsi = gsi_start (stmts2); + while (!gsi_end_p (gsi)) + { + gimple *stmt = gsi_stmt (gsi); + if (is_gimple_assign (stmt) + && arith_code_with_undefined_signed_overflow + (gimple_assign_rhs_code (stmt))) + rewrite_to_defined_overflow (&gsi); + gsi_next (&gsi); + } + } + gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop1), + stmts2); + } tree cond = fold_build2 (guard_code, boolean_type_node, guard_init, border); if (!initial_true) |