From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1923) id 7424D3852C68; Fri, 18 Nov 2022 20:22:27 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 7424D3852C68 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1668802947; bh=xTKxtdyuUSwM7aIRYLPdHIpcA8fzKuzaR+gU7FXx+XE=; h=From:To:Subject:Date:From; b=etbRVdmGO6DNJDF1I5+t5Js1H7/IHOQ2Oncz0UKK5iIzMlyXCMyUCGSnrjclbM4td BDGtr/9oyDWiywcy44A0hjPaEZv4Ki6rGD5vy/Alw2FNo2Fkczs8sQkPIRURP11oRp 4uy79IfOAQIITPGQG81rUCIuffVl+mUdJvDW/RCo= Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Philipp Tomsich To: gcc-cvs@gcc.gnu.org Subject: [gcc(refs/vendors/vrull/heads/for-upstream)] ifcombine: recognize single bit test of sign-bit X-Act-Checkin: gcc X-Git-Author: Philipp Tomsich X-Git-Refname: refs/vendors/vrull/heads/for-upstream X-Git-Oldrev: 015bb8087bce8ec024a8b12648d6fd7b98650dcc X-Git-Newrev: f9ddc8068ab2c79ec3e001845af791c5f6c082d6 Message-Id: <20221118202227.7424D3852C68@sourceware.org> Date: Fri, 18 Nov 2022 20:22:27 +0000 (GMT) List-Id: https://gcc.gnu.org/g:f9ddc8068ab2c79ec3e001845af791c5f6c082d6 commit f9ddc8068ab2c79ec3e001845af791c5f6c082d6 Author: Philipp Tomsich Date: Sun Oct 16 22:34:30 2022 +0200 ifcombine: recognize single bit test of sign-bit Our ifcombine pass combines 2 single-bit tests into a single test of the form "(a & T) == T". However, detection of the bit-tests does not work for sign-bits (of any mode) as the RTL presented to the pass uses a cast to a signed-type and an order-operator. E.g., the test for 'a & 0x80' presents as: _1 = *a_5(D); _2 = (signed char) _1; if (_2 < 0) goto ; else goto ; This adds detection logic to recognize_single_bit_test() for this case and reports it as a single-bit test. gcc/ChangeLog: * tree-ssa-ifcombine.cc (recognize_single_bit_test): Add detection for tests against the sign-bit of the relevant type as a single-bit test. gcc/testsuite/ChangeLog: * gcc.dg/tree-ssa/ssa-ifcombine-14.c: New test. Series-to: gcc-patches@gcc.gnu.org Series-cc: Richard Biener Series-cc: Tamar Christina Series-cc: Jiang-Ning Liu Series-cc: Christoph Muellner Series-cc: Jeff Law Diff: --- gcc/testsuite/gcc.dg/tree-ssa/ssa-ifcombine-14.c | 14 ++++++++++++++ gcc/tree-ssa-ifcombine.cc | 20 ++++++++++++++++++++ 2 files changed, 34 insertions(+) diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-ifcombine-14.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-ifcombine-14.c new file mode 100644 index 00000000000..f9b1115a34a --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-ifcombine-14.c @@ -0,0 +1,14 @@ +/* { dg-do compile } */ +/* { dg-options "-O -fdump-tree-ifcombine-details-blocks" } */ + +void sink(); + +void same(unsigned char *a) +{ + if (*a & 0x80) + if (*a & 0x40) + g(); +} + +/* { dg-final { scan-tree-dump "optimizing double bit test" } } */ + diff --git a/gcc/tree-ssa-ifcombine.cc b/gcc/tree-ssa-ifcombine.cc index 80c41c45489..cd6331f84db 100644 --- a/gcc/tree-ssa-ifcombine.cc +++ b/gcc/tree-ssa-ifcombine.cc @@ -225,6 +225,26 @@ recognize_single_bit_test (gcond *cond, tree *name, tree *bit, bool inv) { gimple *stmt; + /* Handle the test for a sign-bit: + unsigned charD.15 _1; + _2 = (signed char) _1; + if (_2 < 0) */ + if (TREE_CODE (gimple_cond_lhs (cond)) == SSA_NAME + && !TYPE_UNSIGNED (TREE_TYPE (gimple_cond_lhs (cond))) + && gimple_cond_code (cond) == (inv ? GE_EXPR : LT_EXPR) + && integer_zerop (gimple_cond_rhs (cond))) + { + tree type = TREE_TYPE (gimple_cond_lhs (cond)); + + stmt = SSA_NAME_DEF_STMT (gimple_cond_lhs (cond)); + if (!is_gimple_assign (stmt)) + return false; + *name = gimple_assign_rhs1 (stmt); + *bit = build_int_cst (integer_type_node, TYPE_PRECISION (type) - 1); + + return true; + } + /* Get at the definition of the result of the bit test. */ if (gimple_cond_code (cond) != (inv ? EQ_EXPR : NE_EXPR) || TREE_CODE (gimple_cond_lhs (cond)) != SSA_NAME