From: Max Filippov <jcmvbkbc@gmail.com>
To: gcc-patches@gcc.gnu.org
Cc: Max Filippov <jcmvbkbc@gmail.com>
Subject: [COMMITTED 2/2] gcc: xtensa: add -m[no-]strict-align option
Date: Wed, 19 Apr 2023 12:46:36 -0700 [thread overview]
Message-ID: <20230419194636.4006880-2-jcmvbkbc@gmail.com> (raw)
In-Reply-To: <20230419194636.4006880-1-jcmvbkbc@gmail.com>
gcc/
* config/xtensa/xtensa-opts.h: New header.
* config/xtensa/xtensa.h (STRICT_ALIGNMENT): Redefine as
xtensa_strict_align.
* config/xtensa/xtensa.cc (xtensa_option_override): When
-m[no-]strict-align is not specified in the command line set
xtensa_strict_align to 0 if the hardware supports both unaligned
loads and stores or to 1 otherwise.
* config/xtensa/xtensa.opt (mstrict-align): New option.
* doc/invoke.texi (Xtensa Options): Document -m[no-]strict-align.
---
gcc/config/xtensa/xtensa-opts.h | 28 ++++++++++++++++++++++++++++
gcc/config/xtensa/xtensa.cc | 4 ++++
gcc/config/xtensa/xtensa.h | 2 +-
gcc/config/xtensa/xtensa.opt | 7 +++++++
gcc/doc/invoke.texi | 14 +++++++++++++-
5 files changed, 53 insertions(+), 2 deletions(-)
create mode 100644 gcc/config/xtensa/xtensa-opts.h
diff --git a/gcc/config/xtensa/xtensa-opts.h b/gcc/config/xtensa/xtensa-opts.h
new file mode 100644
index 000000000000..f0b8f5b3bfe7
--- /dev/null
+++ b/gcc/config/xtensa/xtensa-opts.h
@@ -0,0 +1,28 @@
+/* Definitions for option handling for Xtensa.
+ Copyright (C) 2023 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
+
+#ifndef XTENSA_OPTS_H
+#define XTENSA_OPTS_H
+
+/* Undefined state for the -mstrict-alignment option */
+enum xtensa_strict_alignment_setting {
+ XTENSA_STRICT_ALIGNMENT_UNDEFINED = -1,
+};
+
+#endif
diff --git a/gcc/config/xtensa/xtensa.cc b/gcc/config/xtensa/xtensa.cc
index 7287aa7a258a..9e5d314e143e 100644
--- a/gcc/config/xtensa/xtensa.cc
+++ b/gcc/config/xtensa/xtensa.cc
@@ -2792,6 +2792,10 @@ xtensa_option_override (void)
if (xtensa_windowed_abi == -1)
xtensa_windowed_abi = TARGET_WINDOWED_ABI_DEFAULT;
+ if (xtensa_strict_alignment == XTENSA_STRICT_ALIGNMENT_UNDEFINED)
+ xtensa_strict_alignment = !XCHAL_UNALIGNED_LOAD_HW
+ || !XCHAL_UNALIGNED_STORE_HW;
+
if (! TARGET_THREADPTR)
targetm.have_tls = false;
diff --git a/gcc/config/xtensa/xtensa.h b/gcc/config/xtensa/xtensa.h
index 8ebf37cab33a..34e06afcff48 100644
--- a/gcc/config/xtensa/xtensa.h
+++ b/gcc/config/xtensa/xtensa.h
@@ -143,7 +143,7 @@ along with GCC; see the file COPYING3. If not see
/* Set this nonzero if move instructions will actually fail to work
when given unaligned data. */
-#define STRICT_ALIGNMENT 1
+#define STRICT_ALIGNMENT (xtensa_strict_alignment)
/* Promote integer modes smaller than a word to SImode. Set UNSIGNEDP
for QImode, because there is no 8-bit load from memory with sign
diff --git a/gcc/config/xtensa/xtensa.opt b/gcc/config/xtensa/xtensa.opt
index 3a129a4c0393..f16b53bf409f 100644
--- a/gcc/config/xtensa/xtensa.opt
+++ b/gcc/config/xtensa/xtensa.opt
@@ -18,6 +18,9 @@
; along with GCC; see the file COPYING3. If not see
; <http://www.gnu.org/licenses/>.
+HeaderInclude
+config/xtensa/xtensa-opts.h
+
mconst16
Target Mask(CONST16)
Use CONST16 instruction to load constants.
@@ -64,3 +67,7 @@ Use call0 ABI.
mabi=windowed
Target RejectNegative Var(xtensa_windowed_abi, 1)
Use windowed registers ABI.
+
+mstrict-align
+Target Var(xtensa_strict_alignment) Init(XTENSA_STRICT_ALIGNMENT_UNDEFINED)
+Do not use unaligned memory references.
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 57fb170ca4cc..54dcccbc148c 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -1474,7 +1474,8 @@ See RS/6000 and PowerPC Options.
-mtarget-align -mno-target-align
-mlongcalls -mno-longcalls
-mabi=@var{abi-type}
--mextra-l32r-costs=@var{cycles}}
+-mextra-l32r-costs=@var{cycles}
+-mstrict-align -mno-strict-align}
@emph{zSeries Options}
See S/390 and zSeries Options.
@@ -34401,6 +34402,17 @@ instructions, in clock cycles. This affects, when optimizing for speed,
whether loading a constant from literal pool using @code{L32R} or
synthesizing the constant from a small one with a couple of arithmetic
instructions. The default value is 0.
+
+@opindex mstrict-align
+@opindex mno-strict-align
+@item -mstrict-align
+@itemx -mno-strict-align
+Avoid or allow generating memory accesses that may not be aligned on a natural
+object boundary as described in the architecture specification.
+The default is @option{-mno-strict-align} for cores that support both
+unaligned loads and stores in hardware and @option{-mstrict-align} for all
+other cores.
+
@end table
@node zSeries Options
--
2.30.2
prev parent reply other threads:[~2023-04-19 19:47 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-19 19:46 [COMMITTED 1/2] gcc: xtensa: add data alignment properties to dynconfig Max Filippov
2023-04-19 19:46 ` Max Filippov [this message]
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