From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-x532.google.com (mail-ed1-x532.google.com [IPv6:2a00:1450:4864:20::532]) by sourceware.org (Postfix) with ESMTPS id C793D385800B for ; Mon, 5 Jul 2021 11:25:56 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org C793D385800B Received: by mail-ed1-x532.google.com with SMTP id j11so23259394edq.6 for ; Mon, 05 Jul 2021 04:25:56 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=CbT53ZyWDYysL3dy/jkhglhxl9EyZ17v4KsHmgTIXtY=; b=uBizCnUdAqiC6gMHXMjWRXis4R9x1JCG1OuLLoXVY/70kHq/l+MIkGvAKr4IsWbLSb WdtYnXakmtLp5QlBxDitFCyANTz/DeN62weJQTs4FP647HvBbhbspTl6zmFOV4XTIWjU Knk7IB3y8X6JNSEYAq2ZQmB0i6Ur64f2o9BVSPW2fElomRUvyJM9OhqhzspF2VqyJu0E pmD7hb84GPZazzSJV0/udFeW4qAw3iacdrp+kZeqIzO599RVjcdPKbHSEVzQ4XeVKQKz HFL4953vn2gUAdQAJi/WgmfyQiwWPTFR1IBcN96mLwKtmZVaj8+AwWYMkkoUhbV6Mgpb Aijw== X-Gm-Message-State: AOAM530hsEmBJ+jvUamXOIucCJGtNmeU4T6u1Sv98rQxvDPiz2bYcTSC xPHOPbPBsD+2HJyQOhVWAfScMGAN/X+KoUyLSEk= X-Google-Smtp-Source: ABdhPJzO10wvkl7miv1649o2sFXusZpThGsDce+Rym325UsGYxtEkk/J1Jb65xCKx0MZSJ3ePPkp2Fs/ZcXohtIuYos= X-Received: by 2002:a05:6402:326:: with SMTP id q6mr15919644edw.248.1625484355747; Mon, 05 Jul 2021 04:25:55 -0700 (PDT) MIME-Version: 1.0 References: <1625423864-20417-1-git-send-email-apinski@marvell.com> In-Reply-To: <1625423864-20417-1-git-send-email-apinski@marvell.com> From: Richard Biener Date: Mon, 5 Jul 2021 13:25:44 +0200 Message-ID: Subject: Re: [PATCH 1/5] Fix 101256: Wrong code due to range incorrect from PHI-OPT To: Andrew Pinski Cc: GCC Patches Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-8.9 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 05 Jul 2021 11:25:59 -0000 On Sun, Jul 4, 2021 at 8:40 PM apinski--- via Gcc-patches wrote: > > From: Andrew Pinski > > So the problem here is that replace_phi_edge_with_variable > will copy range information to a already (not newly) defined > ssa name. This causes wrong code later on. That's a bit too conservative I guess? Shouldn't it work for at least all defs defined in the same block as the original conditional (and thus then applying to the seq inserted there by the callers)? I realize it's wrong for, say _1 = .. if (_1 != 0) { ... if (..) ; # _2 = PHI <_1, 1> ... } with _2 having range [1, +INF] but clearly not _1 at the point of its definition. Richard. > This patch fixes the problem by requiring there to be statements > that are to be placed before the conditional to be able to > copy the range info; this assumes the statements will define > the ssa name. > > gcc/ChangeLog: > > PR tree-optimization/101256 > * dbgcnt.def (phiopt_edge_range): New counter. > * tree-ssa-phiopt.c (replace_phi_edge_with_variable): > Add optional sequence which will be added before the old > conditional. Check sequence for non-null if we want to > update the range. > (two_value_replacement): Instead of inserting the sequence, > update the call to replace_phi_edge_with_variable. > (match_simplify_replacement): Likewise. > (minmax_replacement): Likewise. > (value_replacement): Create a sequence of statements > which would have defined the ssa name. Update call > to replace_phi_edge_with_variable. > > gcc/testsuite/ChangeLog: > > PR tree-optimization/101256 > * g++.dg/torture/pr101256.C: New test. > --- > gcc/dbgcnt.def | 1 + > gcc/testsuite/g++.dg/torture/pr101256.C | 28 +++++++++++++ > gcc/tree-ssa-phiopt.c | 52 ++++++++++++++----------- > 3 files changed, 59 insertions(+), 22 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/torture/pr101256.C > > diff --git a/gcc/dbgcnt.def b/gcc/dbgcnt.def > index 93e7b4fd30e..2345899ba68 100644 > --- a/gcc/dbgcnt.def > +++ b/gcc/dbgcnt.def > @@ -183,6 +183,7 @@ DEBUG_COUNTER (lim) > DEBUG_COUNTER (local_alloc_for_sched) > DEBUG_COUNTER (match) > DEBUG_COUNTER (merged_ipa_icf) > +DEBUG_COUNTER (phiopt_edge_range) > DEBUG_COUNTER (postreload_cse) > DEBUG_COUNTER (pre) > DEBUG_COUNTER (pre_insn) > diff --git a/gcc/testsuite/g++.dg/torture/pr101256.C b/gcc/testsuite/g++.dg/torture/pr101256.C > new file mode 100644 > index 00000000000..973a8b4caf3 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/torture/pr101256.C > @@ -0,0 +1,28 @@ > +// { dg-do run } > + > +template > +const T& max(const T& a, const T& b) > +{ > + return (a < b) ? b : a; > +} > + > +signed char var_5 = -128; > +unsigned int var_11 = 2144479212U; > +unsigned long long int arr [22]; > + > +void > +__attribute__((noipa)) > +test(signed char var_5, unsigned var_11) { > + for (short i_61 = 0; i_61 < var_5 + 149; i_61 += 10000) > + arr[i_61] = max((signed char)0, var_5) ? max((signed char)1, var_5) : var_11; > +} > + > +int main() { > + for (int i_0 = 0; i_0 < 22; ++i_0) > + arr [i_0] = 11834725929543695741ULL; > + > + test(var_5, var_11); > + if (arr [0] != 2144479212ULL && arr [0] != 11834725929543695741ULL) > + __builtin_abort (); > + return 0; > +} > diff --git a/gcc/tree-ssa-phiopt.c b/gcc/tree-ssa-phiopt.c > index ab12e85569d..71f0019d877 100644 > --- a/gcc/tree-ssa-phiopt.c > +++ b/gcc/tree-ssa-phiopt.c > @@ -50,6 +50,7 @@ along with GCC; see the file COPYING3. If not see > #include "gimple-fold.h" > #include "internal-fn.h" > #include "gimple-range.h" > +#include "dbgcnt.h" > > static unsigned int tree_ssa_phiopt_worker (bool, bool, bool); > static bool two_value_replacement (basic_block, basic_block, edge, gphi *, > @@ -73,7 +74,8 @@ static bool cond_store_replacement (basic_block, basic_block, edge, edge, > hash_set *); > static bool cond_if_else_store_replacement (basic_block, basic_block, basic_block); > static hash_set * get_non_trapping (); > -static void replace_phi_edge_with_variable (basic_block, edge, gphi *, tree); > +static void replace_phi_edge_with_variable (basic_block, edge, gphi *, tree, > + gimple_seq = NULL); > static void hoist_adjacent_loads (basic_block, basic_block, > basic_block, basic_block); > static bool gate_hoist_loads (void); > @@ -382,18 +384,20 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads, bool early_p) > > /* Replace PHI node element whose edge is E in block BB with variable NEW. > Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK > - is known to have two edges, one of which must reach BB). */ > + is known to have two edges, one of which must reach BB). > + Optionally insert stmts before the old condition. */ > > static void > replace_phi_edge_with_variable (basic_block cond_block, > - edge e, gphi *phi, tree new_tree) > + edge e, gphi *phi, tree new_tree, > + gimple_seq stmts) > { > basic_block bb = gimple_bb (phi); > basic_block block_to_remove; > gimple_stmt_iterator gsi; > tree phi_result = PHI_RESULT (phi); > > - /* Duplicate range info if we're the only things setting the target PHI. > + /* Duplicate range info if they are the only things setting the target PHI. > This is needed as later on, the new_tree will be replacing > The assignement of the PHI. > For an example: > @@ -401,19 +405,23 @@ replace_phi_edge_with_variable (basic_block cond_block, > _4 = min > goto bb2 > > - range<-INF,255> > + # RANGE [-INF, 255] > a_3 = PHI<_4(1)> > bb3: > > use(a_3) > - And _4 gets prograted into the use of a_3 and losing the range info. > - This can't be done for more than 2 incoming edges as the progration > - won't happen. */ > + And _4 gets propagated into the use of a_3 and losing the range info. > + This can't be done for more than 2 incoming edges as the propagation > + won't happen. > + This also cannot be done if the name is not defined by statements to > + be placed before the conditional. */ > if (TREE_CODE (new_tree) == SSA_NAME > && EDGE_COUNT (gimple_bb (phi)->preds) == 2 > && INTEGRAL_TYPE_P (TREE_TYPE (phi_result)) > && !SSA_NAME_RANGE_INFO (new_tree) > - && SSA_NAME_RANGE_INFO (phi_result)) > + && SSA_NAME_RANGE_INFO (phi_result) > + && stmts != NULL > + && dbg_cnt (phiopt_edge_range)) > duplicate_ssa_name_range_info (new_tree, > SSA_NAME_RANGE_TYPE (phi_result), > SSA_NAME_RANGE_INFO (phi_result)); > @@ -443,6 +451,8 @@ replace_phi_edge_with_variable (basic_block cond_block, > > /* Eliminate the COND_EXPR at the end of COND_BLOCK. */ > gsi = gsi_last_bb (cond_block); > + if (stmts) > + gsi_insert_seq_before (&gsi, stmts, GSI_SAME_STMT); > gsi_remove (&gsi, true); > > statistics_counter_event (cfun, "Replace PHI with variable", 1); > @@ -802,10 +812,8 @@ two_value_replacement (basic_block cond_bb, basic_block middle_bb, > else > new_rhs = gimple_build (&stmts, MINUS_EXPR, type, arg, lhs); > new_rhs = gimple_convert (&stmts, TREE_TYPE (arg0), new_rhs); > - gimple_stmt_iterator gsi = gsi_for_stmt (stmt); > - gsi_insert_seq_before (&gsi, stmts, GSI_SAME_STMT); > > - replace_phi_edge_with_variable (cond_bb, e1, phi, new_rhs); > + replace_phi_edge_with_variable (cond_bb, e1, phi, new_rhs, stmts); > > /* Note that we optimized this PHI. */ > return true; > @@ -920,10 +928,8 @@ match_simplify_replacement (basic_block cond_bb, basic_block middle_bb, > gsi_move_before (&gsi1, &gsi); > reset_flow_sensitive_info (gimple_assign_lhs (stmt_to_move)); > } > - if (seq) > - gsi_insert_seq_before (&gsi, seq, GSI_SAME_STMT); > > - replace_phi_edge_with_variable (cond_bb, e1, phi, result); > + replace_phi_edge_with_variable (cond_bb, e1, phi, result, seq); > > /* Add Statistic here even though replace_phi_edge_with_variable already > does it as we want to be able to count when match-simplify happens vs > @@ -1396,6 +1402,7 @@ value_replacement (basic_block cond_bb, basic_block middle_bb, > && absorbing_element_p (code_def, > cond_rhs, false, rhs2)))))) > { > + gimple_seq stmts = NULL; > gsi = gsi_for_stmt (cond); > /* Moving ASSIGN might change VR of lhs, e.g. when moving u_6 > def-stmt in: > @@ -1417,11 +1424,15 @@ value_replacement (basic_block cond_bb, basic_block middle_bb, > tree plhs = gimple_assign_lhs (prep_stmt[i]); > reset_flow_sensitive_info (plhs); > gsi_from = gsi_for_stmt (prep_stmt[i]); > - gsi_move_before (&gsi_from, &gsi); > + gsi_remove (&gsi_from, false); > + > + gimple_seq_add_stmt (&stmts, prep_stmt[i]); > } > gsi_from = gsi_for_stmt (assign); > - gsi_move_before (&gsi_from, &gsi); > - replace_phi_edge_with_variable (cond_bb, e1, phi, lhs); > + gsi_remove (&gsi_from, false); > + gimple_seq_add_stmt (&stmts, assign); > + > + replace_phi_edge_with_variable (cond_bb, e1, phi, lhs, stmts); > return 2; > } > > @@ -1811,10 +1822,7 @@ minmax_replacement (basic_block cond_bb, basic_block middle_bb, > tree phi_result = PHI_RESULT (phi); > result = gimple_build (&stmts, minmax, TREE_TYPE (phi_result), arg0, arg1); > > - gsi = gsi_last_bb (cond_bb); > - gsi_insert_seq_before (&gsi, stmts, GSI_NEW_STMT); > - > - replace_phi_edge_with_variable (cond_bb, e1, phi, result); > + replace_phi_edge_with_variable (cond_bb, e1, phi, result, stmts); > > return true; > } > -- > 2.27.0 >