https://gcc.gnu.org/g:9d6ff6f1ea2ae7fc32ec9fbd0554fb06238ed045
commit r14-9589-g9d6ff6f1ea2ae7fc32ec9fbd0554fb06238ed045 Author: Richard Biener <rguent...@suse.de> Date: Tue Mar 19 14:50:06 2024 +0100 tree-optimization/113727 - bogus SRA with BIT_FIELD_REF When SRA analyzes BIT_FIELD_REFs it handles writes and not byte aligned reads differently from byte aligned reads. Instead of trying to create replacements for the loaded portion the former cases try to replace the base object while keeping the wrapping BIT_FIELD_REFs. This breaks when we have both kinds operating on the same base object if there's no appearant overlap conflict as the conflict that then nevertheless exists isn't handled with. The fix is to enforce what I think is part of the design handling the former case - that only the full base object gets replaced and no further sub-objects are created within as otherwise keeping the wrapping BIT_FIELD_REF cannot work. The patch enforces this within analyze_access_subtree. PR tree-optimization/113727 * tree-sra.cc (analyze_access_subtree): Do not allow replacements in subtrees when grp_partial_lhs. * gcc.dg/torture/pr113727.c: New testcase. Diff: --- gcc/testsuite/gcc.dg/torture/pr113727.c | 26 ++++++++++++++++++++++++++ gcc/tree-sra.cc | 3 ++- 2 files changed, 28 insertions(+), 1 deletion(-) diff --git a/gcc/testsuite/gcc.dg/torture/pr113727.c b/gcc/testsuite/gcc.dg/torture/pr113727.c new file mode 100644 index 00000000000..f92ddad5c8e --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr113727.c @@ -0,0 +1,26 @@ +/* { dg-do run } */ +/* { dg-require-effective-target int32plus } */ + +struct f { + unsigned au : 5; + unsigned f3 : 21; +} g_994; + +int main() +{ + struct f aq1 = {}; + { + struct f aq = {9, 5}; + struct f as = aq; + for (int y = 0 ; y <= 4; y += 1) + if (as.au) + { + struct f aa[5] = {{2, 154}, {2, 154}, {2, 154}, {2, 154}, {2, 154}}; + as = aa[0]; + } + aq1 = as; + } + if (aq1.f3 != 0x9a) + __builtin_abort(); + return 0; +} diff --git a/gcc/tree-sra.cc b/gcc/tree-sra.cc index f8e71ec48b9..dbfae5e7fdd 100644 --- a/gcc/tree-sra.cc +++ b/gcc/tree-sra.cc @@ -2735,7 +2735,8 @@ analyze_access_subtree (struct access *root, struct access *parent, { hole |= covered_to < child->offset; sth_created |= analyze_access_subtree (child, root, - allow_replacements && !scalar, + allow_replacements && !scalar + && !root->grp_partial_lhs, totally); root->grp_unscalarized_data |= child->grp_unscalarized_data;