https://gcc.gnu.org/PR111860 https://gcc.gnu.org/git/gitweb.cgi?p=gcc.git;h=9ed6b22eb4188c57bb3f5cdba5a7effa95395186 From 9ed6b22eb4188c57bb3f5cdba5a7effa95395186 Mon Sep 17 00:00:00 2001 From: Tamar Christina Date: Mon, 23 Oct 2023 14:07:20 +0100 Subject: [PATCH] middle-end: don't keep .MEM guard nodes for PHI nodes who dominate loop [PR111860] The previous patch tried to remove PHI nodes that dominated the first loop, however the correct fix is to only remove .MEM nodes. This patch thus makes the condition a bit stricter and only tries to remove MEM phi nodes. I couldn't figure out a way to easily determine if a particular PHI is vUSE related, so the patch does: 1. check if the definition is a vDEF and not defined in main loop. 2. check if the definition is a PHI and not defined in main loop. 3. check if the definition is a default definition. For no 2 and 3 we may misidentify the PHI, in both cases the value is defined outside of the loop version block which also makes it ok to remove. gcc/ChangeLog: PR tree-optimization/111860 * tree-vect-loop-manip.cc (slpeel_tree_duplicate_loop_to_edge_cfg): Drop .MEM nodes only. gcc/testsuite/ChangeLog: PR tree-optimization/111860 * gcc.dg/vect/pr111860-2.c: New test. * gcc.dg/vect/pr111860-3.c: New test. --- gcc/testsuite/gcc.dg/vect/pr111860-2.c | 17 +++++++++++++++++ gcc/testsuite/gcc.dg/vect/pr111860-3.c | 17 +++++++++++++++++ gcc/tree-vect-loop-manip.cc | 21 ++++++++++++++++++++- 3 files changed, 54 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/vect/pr111860-2.c create mode 100644 gcc/testsuite/gcc.dg/vect/pr111860-3.c diff --git a/gcc/testsuite/gcc.dg/vect/pr111860-2.c b/gcc/testsuite/gcc.dg/vect/pr111860-2.c new file mode 100644 index 000000000000..07f64ffb5318 --- /dev/null +++ b/gcc/testsuite/gcc.dg/vect/pr111860-2.c @@ -0,0 +1,17 @@ +/* { dg-do compile } */ +/* { dg-options "-O -fno-tree-sink -ftree-vectorize" } */ +int buffer_ctrl_ctx_0, buffer_ctrl_p1, buffer_ctrl_cmd; + +int +buffer_ctrl (long ret, int i) +{ + switch (buffer_ctrl_cmd) + { + case 1: + buffer_ctrl_ctx_0 = 0; + for (; i; i++) + if (buffer_ctrl_p1) + ret++; + } + return ret; +} diff --git a/gcc/testsuite/gcc.dg/vect/pr111860-3.c b/gcc/testsuite/gcc.dg/vect/pr111860-3.c new file mode 100644 index 000000000000..07f64ffb5318 --- /dev/null +++ b/gcc/testsuite/gcc.dg/vect/pr111860-3.c @@ -0,0 +1,17 @@ +/* { dg-do compile } */ +/* { dg-options "-O -fno-tree-sink -ftree-vectorize" } */ +int buffer_ctrl_ctx_0, buffer_ctrl_p1, buffer_ctrl_cmd; + +int +buffer_ctrl (long ret, int i) +{ + switch (buffer_ctrl_cmd) + { + case 1: + buffer_ctrl_ctx_0 = 0; + for (; i; i++) + if (buffer_ctrl_p1) + ret++; + } + return ret; +} diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc index d67c94700144..43ca985c53ce 100644 --- a/gcc/tree-vect-loop-manip.cc +++ b/gcc/tree-vect-loop-manip.cc @@ -1626,12 +1626,31 @@ slpeel_tree_duplicate_loop_to_edge_cfg (class loop *loop, edge loop_exit, edge temp_e = redirect_edge_and_branch (exit, new_preheader); flush_pending_stmts (temp_e); } - /* Record the new SSA names in the cache so that we can skip materializing them again when we fill in the rest of the LCSSA variables. */ for (auto phi : new_phis) { tree new_arg = gimple_phi_arg (phi, 0)->def; + + if (!SSA_VAR_P (new_arg)) + continue; + /* If the PHI MEM node dominates the loop then we shouldn't create + a new LC-SSSA PHI for it in the intermediate block. */ + /* A MEM phi that consitutes a new DEF for the vUSE chain can either + be a .VDEF or a PHI that operates on MEM. And said definition + must not be inside the main loop. Or we must be a parameter. + In the last two cases we may remove a non-MEM PHI node, but since + they dominate both loops the removal is unlikely to cause trouble + as the exits must already be using them. */ + if (virtual_operand_p (new_arg) + && (SSA_NAME_IS_DEFAULT_DEF (new_arg) + || !flow_bb_inside_loop_p (loop, + gimple_bb (SSA_NAME_DEF_STMT (new_arg))))) + { + auto gsi = gsi_for_stmt (phi); + remove_phi_node (&gsi, true); + continue; + } new_phi_args.put (new_arg, gimple_phi_result (phi)); if (TREE_CODE (new_arg) != SSA_NAME) -- 2.39.3