Hi All,
This patch allows larger bitsizes to be used as copy size
when the target does not have SLOW_UNALIGNED_ACCESS.
fun3:
adrp x2, .LANCHOR0
add x2, x2, :lo12:.LANCHOR0
mov x0, 0
sub sp, sp, #16
ldrh w1, [x2, 16]
ldrb w2, [x2, 18]
add sp, sp, 16
bfi x0, x1, 0, 8
ubfx x1, x1, 8, 8
bfi x0, x1, 8, 8
bfi x0, x2, 16, 8
ret
is turned into
fun3:
adrp x0, .LANCHOR0
add x0, x0, :lo12:.LANCHOR0
sub sp, sp, #16
ldrh w1, [x0, 16]
ldrb w0, [x0, 18]
strh w1, [sp, 8]
strb w0, [sp, 10]
ldr w0, [sp, 8]
add sp, sp, 16
ret
which avoids the bfi's for a simple 3 byte struct copy.
Regression tested on aarch64-none-linux-gnu and x86_64-pc-linux-gnu and no
regressions.
This patch is just splitting off from the previous combined patch with AArch64
and adding
a testcase.
I assume Jeff's ACK from
https://gcc.gnu.org/ml/gcc-patches/2017-08/msg01523.html is still
valid as the code did not change.
Thanks,
Tamar
gcc/
2017-11-14 Tamar Christina <tamar.christ...@arm.com>
* expr.c (copy_blkmode_to_reg): Fix bitsize for targets
with fast unaligned access.
* doc/sourcebuild.texi (no_slow_unalign): New.
gcc/testsuite/
2017-11-14 Tamar Christina <tamar.christ...@arm.com>
* gcc.dg/struct-simple.c: New.
* lib/target-supports.exp
(check_effective_target_no_slow_unalign): New.
--
diff --git a/gcc/doc/sourcebuild.texi b/gcc/doc/sourcebuild.texi
index 1646d0a99911aa7b2e66762e5907fbb0454ed00d..1df7a82fbd516b9bf07908bb800e441110b28ca4 100644
--- a/gcc/doc/sourcebuild.texi
+++ b/gcc/doc/sourcebuild.texi
@@ -2178,8 +2178,12 @@ Target supports @code{wchar_t} that is compatible with @code{char32_t}.
@item comdat_group
Target uses comdat groups.
+
+@item no_slow_unalign
+Target does not have slow unaligned access.
@end table
+
@subsubsection Local to tests in @code{gcc.target/i386}
@table @code
diff --git a/gcc/expr.c b/gcc/expr.c
index 2f8432d92ccac17c0a548faf4a16eff0656cef1b..afcea8fef58155d0a899991c10cd485ba8af888d 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -2769,7 +2769,9 @@ copy_blkmode_to_reg (machine_mode mode, tree src)
n_regs = (bytes + UNITS_PER_WORD - 1) / UNITS_PER_WORD;
dst_words = XALLOCAVEC (rtx, n_regs);
- bitsize = MIN (TYPE_ALIGN (TREE_TYPE (src)), BITS_PER_WORD);
+ bitsize = BITS_PER_WORD;
+ if (targetm.slow_unaligned_access (word_mode, TYPE_ALIGN (TREE_TYPE (src))))
+ bitsize = MIN (TYPE_ALIGN (TREE_TYPE (src)), BITS_PER_WORD);
/* Copy the structure BITSIZE bits at a time. */
for (bitpos = 0, xbitpos = padding_correction;
diff --git a/gcc/testsuite/gcc.dg/struct-simple.c b/gcc/testsuite/gcc.dg/struct-simple.c
new file mode 100644
index 0000000000000000000000000000000000000000..9f218851d897421b217b0926d29845b6192982fb
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/struct-simple.c
@@ -0,0 +1,52 @@
+/* { dg-do-run } */
+/* { dg-require-effective-target no_slow_unalign } */
+/* { dg-additional-options "-fdump-rtl-final" } */
+
+/* Copyright 1996, 1999, 2007 Free Software Foundation, Inc.
+
+ This program 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 of the License, or
+ (at your option) any later version.
+
+ This program 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/>.
+
+ Please email any bugs, comments, and/or additions to this file to:
+ bug-...@prep.ai.mit.edu */
+
+#include <stdio.h>
+
+struct struct3 { char a, b, c; };
+struct struct3 foo3 = { 'A', 'B', 'C'}, L3;
+
+struct struct3 fun3()
+{
+ return foo3;
+}
+
+#ifdef PROTOTYPES
+void Fun3(struct struct3 foo3)
+#else
+void Fun3(foo3)
+ struct struct3 foo3;
+#endif
+{
+ L3 = foo3;
+}
+
+int main()
+{
+ struct struct3 x = fun3();
+
+ printf("a:%c, b:%c, c:%c\n", x.a, x.b, x.c);
+}
+
+/* { dg-final { scan-rtl-dump-not {zero_extract:.+\[\s*foo3\s*\]} "final" } } */
+
diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index b6f9e51c4817cf8235c8e33b14e2763308eb482a..690d8960002a3c38462bbe5524b419c205ba4da9 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -6037,6 +6037,30 @@ proc check_effective_target_unaligned_stack { } {
return $et_unaligned_stack_saved
}
+# Return 1 if the target plus current options does not have
+# slow unaligned access.
+#
+# This won't change for different subtargets so cache the result.
+
+proc check_effective_target_no_slow_unalign { } {
+ global et_no_slow_unalign_saved
+ global et_index
+
+ if [info exists et_no_slow_unalign_saved($et_index)] {
+ verbose "check_effective_target_no_slow_unalign: using cached result" 2
+ } else {
+ set et_no_slow_unalign_saved($et_index) 0
+ if { [istarget x86_64-*-*]
+ || [istarget aarch64*-*-*]
+ } {
+ set et_no_slow_unalign_saved($et_index) 1
+ }
+ }
+ verbose "check_effective_target_no_slow_unalign:\
+ returning $et_no_slow_unalign_saved($et_index)" 2
+ return $et_no_slow_unalign_saved($et_index)
+}
+
# Return 1 if the target plus current options does not support a vector
# alignment mechanism, 0 otherwise.
#
