From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 79318 invoked by alias); 29 May 2019 12:36:21 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 79309 invoked by uid 89); 29 May 2019 12:36:21 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-17.4 required=5.0 tests=AWL,BAYES_00,GIT_PATCH_0,GIT_PATCH_1,GIT_PATCH_2,GIT_PATCH_3,SPF_PASS,UNSUBSCRIBE_BODY autolearn=ham version=3.3.1 spammy=ack, ACK X-HELO: mx1.suse.de Received: from mx2.suse.de (HELO mx1.suse.de) (195.135.220.15) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 29 May 2019 12:36:19 +0000 Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 6D127AC8A; Wed, 29 May 2019 12:36:17 +0000 (UTC) Date: Wed, 29 May 2019 12:40:00 -0000 From: Richard Biener To: Jiufu Guo cc: gcc-patches@gcc.gnu.org, Jakub Jelinek , Daniel Berlin , segher@kernel.crashing.org, wschmidt@linux.ibm.com, law@redhat.com Subject: Re: [PATCH V2] A jump threading opportunity for condition branch In-Reply-To: Message-ID: References: <1558446288-52444-1-git-send-email-guojiufu@linux.ibm.com> User-Agent: Alpine 2.20 (LSU 67 2015-01-07) MIME-Version: 1.0 Content-Type: multipart/mixed; BOUNDARY="-1609908220-110764456-1559133377=:10704" X-SW-Source: 2019-05/txt/msg01891.txt.bz2 This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. ---1609908220-110764456-1559133377=:10704 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 8BIT Content-length: 10108 On Tue, 28 May 2019, Jiufu Guo wrote: > Hi, > > This patch implements a new opportunity of jump threading for PR77820. > In this optimization, conditional jumps are merged with unconditional > jump. And then moving CMP result to GPR is eliminated. > > This version is based on the proposal of Richard, Jeff and Andrew, and > refined to incorporate comments. Thanks for the reviews! > > Bootstrapped and tested on powerpc64le and powerpc64be with no > regressions (one case is improved) and new testcases are added. Is this > ok for trunk? > > Example of this opportunity looks like below: > > > p0 = a CMP b > goto ; > > > p1 = c CMP d > goto ; > > > # phi = PHI > if (phi != 0) goto ; else goto ; > > Could be transformed to: > > > p0 = a CMP b > if (p0 != 0) goto ; else goto ; > > > p1 = c CMP d > if (p1 != 0) goto ; else goto ; > > > This optimization eliminates: > 1. saving CMP result: p0 = a CMP b. > 2. additional CMP on branch: if (phi != 0). > 3. converting CMP result if there is phi = (INT_CONV) p0 if there is. > > Thanks! > Jiufu Guo > > > [gcc] > 2019-05-28 Jiufu Guo > Lijia He > > PR tree-optimization/77820 > * tree-ssa-threadedge.c > (edge_forwards_cmp_to_conditional_jump_through_empty_bb_p): New > function. > (thread_across_edge): Add call to > edge_forwards_cmp_to_conditional_jump_through_empty_bb_p. > > [gcc/testsuite] > 2019-05-28 Jiufu Guo > Lijia He > > PR tree-optimization/77820 > * gcc.dg/tree-ssa/phi_on_compare-1.c: New testcase. > * gcc.dg/tree-ssa/phi_on_compare-2.c: New testcase. > * gcc.dg/tree-ssa/phi_on_compare-3.c: New testcase. > * gcc.dg/tree-ssa/phi_on_compare-4.c: New testcase. > * gcc.dg/tree-ssa/split-path-6.c: Update testcase. > > --- > gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-1.c | 30 ++++++++++ > gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-2.c | 23 +++++++ > gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-3.c | 25 ++++++++ > gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-4.c | 40 +++++++++++++ > gcc/testsuite/gcc.dg/tree-ssa/split-path-6.c | 2 +- > gcc/tree-ssa-threadedge.c | 76 +++++++++++++++++++++++- > 6 files changed, 192 insertions(+), 4 deletions(-) > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-1.c > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-2.c > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-3.c > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-4.c > > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-1.c b/gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-1.c > new file mode 100644 > index 0000000..5227c87 > --- /dev/null > +++ b/gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-1.c > @@ -0,0 +1,30 @@ > +/* { dg-do compile } */ > +/* { dg-options "-Ofast -fdump-tree-vrp1" } */ > + > +void g (int); > +void g1 (int); > + > +void > +f (long a, long b, long c, long d, long x) > +{ > + _Bool t; > + if (x) > + { > + g (a + 1); > + t = a < b; > + c = d + x; > + } > + else > + { > + g (b + 1); > + a = c + d; > + t = c > d; > + } > + > + if (t) > + g1 (c); > + > + g (a); > +} > + > +/* { dg-final { scan-tree-dump-times "Removing basic block" 1 "vrp1" } } */ > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-2.c b/gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-2.c > new file mode 100644 > index 0000000..eaf89bb > --- /dev/null > +++ b/gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-2.c > @@ -0,0 +1,23 @@ > +/* { dg-do compile } */ > +/* { dg-options "-Ofast -fdump-tree-vrp1" } */ > + > +void g (void); > +void g1 (void); > + > +void > +f (long a, long b, long c, long d, int x) > +{ > + _Bool t; > + if (x) > + t = c < d; > + else > + t = a < b; > + > + if (t) > + { > + g1 (); > + g (); > + } > +} > + > +/* { dg-final { scan-tree-dump-times "Removing basic block" 1 "vrp1" } } */ > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-3.c b/gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-3.c > new file mode 100644 > index 0000000..d5a1e0b > --- /dev/null > +++ b/gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-3.c > @@ -0,0 +1,25 @@ > +/* { dg-do compile } */ > +/* { dg-options "-Ofast -fdump-tree-vrp1" } */ > + > +void g (void); > +void g1 (void); > + > +void > +f (long a, long b, long c, long d, int x) > +{ > + int t; > + if (x) > + t = a < b; > + else if (d == x) > + t = c < b; > + else > + t = d > c; > + > + if (t) > + { > + g1 (); > + g (); > + } > +} > + > +/* { dg-final { scan-tree-dump-times "Removing basic block" 1 "vrp1" } } */ > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-4.c b/gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-4.c > new file mode 100644 > index 0000000..53acabc > --- /dev/null > +++ b/gcc/testsuite/gcc.dg/tree-ssa/phi_on_compare-4.c > @@ -0,0 +1,40 @@ > +/* { dg-do compile } */ > +/* { dg-options "-Ofast -fdump-tree-vrp1" } */ > + > +void g (int); > +void g1 (int); > + > +void > +f (long a, long b, long c, long d, int x) > +{ > + int t; > + _Bool l1 = 0, l2 = 0; > + if (x) > + { > + g (a); > + c = a + b; > + t = a < b; > + l1 = 1; > + } > + else > + { > + g1 (b); > + t = c > d; > + d = c + b; > + l2 = 1; > + } > + > + if (t) > + { > + if (l1 | l2) > + g1 (c); > + } > + else > + { > + g (d); > + g1 (a + b); > + } > + g (c + d); > +} > + > +/* { dg-final { scan-tree-dump-times "Removing basic block" 1 "vrp1" } } */ > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/split-path-6.c b/gcc/testsuite/gcc.dg/tree-ssa/split-path-6.c > index e9b4f26..1d7b587 100644 > --- a/gcc/testsuite/gcc.dg/tree-ssa/split-path-6.c > +++ b/gcc/testsuite/gcc.dg/tree-ssa/split-path-6.c > @@ -69,4 +69,4 @@ lookharder (string) > } > } > > -/* { dg-final { scan-tree-dump-times "Duplicating join block" 3 "split-paths" } } */ > +/* { dg-final { scan-tree-dump-times "Duplicating join block" 2 "split-paths" } } */ > diff --git a/gcc/tree-ssa-threadedge.c b/gcc/tree-ssa-threadedge.c > index c3ea2d6..36c413a 100644 > --- a/gcc/tree-ssa-threadedge.c > +++ b/gcc/tree-ssa-threadedge.c > @@ -1157,6 +1157,74 @@ thread_through_normal_block (edge e, > return 0; > } > > +/* There are basic blocks look like: > + > + p0 = a CMP b ; or p0 = (INT) (a CMP b) > + goto ; > + > + > + p1 = c CMP d > + goto ; > + > + > + # phi = PHI > + if (phi != 0) goto ; else goto ; > + > + Then, edge (P0,X) or (P1,X) could be marked as EDGE_START_JUMP_THREAD > + And edge (X,Y), (X,Z) is EDGE_COPY_SRC_JOINER_BLOCK > + > + Return true if E is (P0,X) or (P1,X) */ > + > +bool > +edge_forwards_cmp_to_conditional_jump_through_empty_bb_p (edge e) > +{ > + basic_block bb = e->dest; > + > + /* See if there is only one stmt which is gcond. */ > + gimple *gs = last_and_only_stmt (bb); > + if (gs == NULL || gimple_code (gs) != GIMPLE_COND) > + return false; gcond *gs; if (!(gs = safe_dyn_cast (last_and_only_stmt (bb)))) return false; makes the following gimple_cond_ accesses more efficient when checking is enabled. > + > + /* See if gcond's cond is "(phi !=/== 0/1)" in the basic block. */ > + tree cond = gimple_cond_lhs (gs); > + enum tree_code code = gimple_cond_code (gs); > + tree rhs = gimple_cond_rhs (gs); > + if (TREE_CODE (cond) != SSA_NAME > + || (code != NE_EXPR && code != EQ_EXPR) > + || (!integer_onep (rhs) && !integer_zerop (rhs))) > + return false; > + gphi *phi = dyn_cast (SSA_NAME_DEF_STMT (cond)); > + if (phi == NULL || gimple_bb (phi) != bb) > + return false; > + > + /* Check if phi's incoming value is CMP. */ > + gimple *def; > + tree value = PHI_ARG_DEF_FROM_EDGE (phi, e); > + if (TREE_CODE (value) == SSA_NAME > + && has_single_use (value) > + && is_gimple_assign (SSA_NAME_DEF_STMT (value))) > + def = SSA_NAME_DEF_STMT (value); Same is true here and below if you rewrite to gassign *def; tree value = PHI_ARG_DEF_FROM_EDGE (phi, e); if (TREE_CODE (value) != SSA_NAME || !has_single_use (value) || !(def = dyn_cast (SSA_NAME_DEF_STMT (value)))) return false; Otherwise it looks good. I'd like to have Jeffs opinion and final ACK here because we touch jump-threading and he's most familiar with that detail and the place you hook into. Thanks, Richard. > + else > + return false; > + > + /* Or if it is (INT) (a CMP b). */ > + if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def))) > + { > + value = gimple_assign_rhs1 (def); > + if (TREE_CODE (value) == SSA_NAME > + && has_single_use (value) > + && is_gimple_assign (SSA_NAME_DEF_STMT (value))) > + def = SSA_NAME_DEF_STMT (value); > + else > + return false; > + } > + > + if (TREE_CODE_CLASS (gimple_assign_rhs_code (def)) != tcc_comparison) > + return false; > + > + return true; > +} > + > /* We are exiting E->src, see if E->dest ends with a conditional > jump which has a known value when reached via E. > > @@ -1317,10 +1385,12 @@ thread_across_edge (gcond *dummy_cond, > > /* If we were able to thread through a successor of E->dest, then > record the jump threading opportunity. */ > - if (found) > + if (found > + || edge_forwards_cmp_to_conditional_jump_through_empty_bb_p (e)) > { > - propagate_threaded_block_debug_into (path->last ()->e->dest, > - taken_edge->dest); > + if (taken_edge->dest != path->last ()->e->dest) > + propagate_threaded_block_debug_into (path->last ()->e->dest, > + taken_edge->dest); > register_jump_thread (path); > } > else > -- Richard Biener SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany; GF: Felix Imendörffer, Mary Higgins, Sri Rasiah; HRB 21284 (AG Nürnberg) ---1609908220-110764456-1559133377=:10704--