From cf68f5a6d20db2aee2f3e674ad3f10e1c458edf9 Mon Sep 17 00:00:00 2001 From: Martin Jambor Date: Thu, 31 Mar 2022 17:14:42 +0200 Subject: [PATCH] ipa-cp: Do not create clones for values outside known value range (PR 102513) PR 102513 shows we emit bogus array access warnings when IPA-CP creates clones specialized for values which it deduces from arithmetic jump functions describing self-recursive calls. Those can however be avoided if we consult the IPA-VR information that the same pass also has. The patch below does that at the stage when normally values are only examined for profitability. It would be better not to create lattices describing such bogus values in the first place, however that presents an ordering problem, the pass currently propagates all information, and so both constants and VR, in no particular order when processing SCCs, and so this approach seemed much simpler. I plan to rearrange the pass so that it clones in multiple passes over the call graph (or rather the lattice dependence graph) and it feels natural to only do propagation for these kinds of recursion in the second or later passes, which would fix the issue more elegantly. gcc/ChangeLog: 2022-02-14 Martin Jambor PR ipa/102513 * ipa-cp.cc (decide_whether_version_node): Skip scalar values which do not fit the known value_range. gcc/testsuite/ChangeLog: 2022-02-14 Martin Jambor PR ipa/102513 * gcc.dg/ipa/pr102513.c: New test. --- gcc/ipa-cp.cc | 28 ++++++++++++++++++++++++++-- gcc/testsuite/gcc.dg/ipa/pr102513.c | 33 +++++++++++++++++++++++++++++++++ 2 files changed, 59 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/ipa/pr102513.c diff --git a/gcc/ipa-cp.cc b/gcc/ipa-cp.cc index 18047c2..8628140 100644 --- a/gcc/ipa-cp.cc +++ b/gcc/ipa-cp.cc @@ -6154,8 +6154,32 @@ decide_whether_version_node (struct cgraph_node *node) { ipcp_value *val; for (val = lat->values; val; val = val->next) - ret |= decide_about_value (node, i, -1, val, &avals, - &self_gen_clones); + { + /* If some values generated for self-recursive calls with + arithmetic jump functions fall outside of the known + value_range for the parameter, we can skip them. VR interface + supports this only for integers now. */ + if (TREE_CODE (val->value) == INTEGER_CST + && !plats->m_value_range.bottom_p () + && !plats->m_value_range.m_vr.contains_p (val->value)) + { + /* This can happen also if a constant present in the source + code falls outside of the range of parameter's type, so we + cannot assert. */ + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, " - skipping%s value ", + val->self_recursion_generated_p () + ? " self_recursion_generated" : ""); + print_ipcp_constant_value (dump_file, val->value); + fprintf (dump_file, " because it is outside known " + "value range.\n"); + } + continue; + } + ret |= decide_about_value (node, i, -1, val, &avals, + &self_gen_clones); + } } if (!plats->aggs_bottom) diff --git a/gcc/testsuite/gcc.dg/ipa/pr102513.c b/gcc/testsuite/gcc.dg/ipa/pr102513.c new file mode 100644 index 0000000..9ee5431 --- /dev/null +++ b/gcc/testsuite/gcc.dg/ipa/pr102513.c @@ -0,0 +1,33 @@ +/* { dg-do compile } */ +/* { dg-options "-O3 -Warray-bounds" } */ + +extern int block2[7][256]; + +static int encode_block(int block2[7][256], unsigned level) +{ + int best_score = 0; + + for (unsigned x = 0; x < level; x++) { + int v = block2[1][x]; + block2[level][x] = 0; + best_score += v * v; + } + + if (level > 0 && best_score > 64) { + int score = 0; + + score += encode_block(block2, level - 1); + score += encode_block(block2, level - 1); + + if (score < best_score) { + best_score = score; + } + } + + return best_score; +} + +int foo(void) +{ + return encode_block(block2, 5); +} -- 2.7.4