Hi Richard,
>
> I'd have made it
>
> if { ([is-effective-target non_strict_align]
> && ! ( [istarget ...] || ....))
>
> thus default it to 1 for non-strict-align targets.
>
Fair, I've switched it to a black list and have excluded the only one I know
should not work. Most of the rest will get blocked by non_strict_align and for
the
few others I'll adjust the testcase accordingly if there are any issues.
> > But this also raises a question, some targets have defined
> > SLOW_UNALIGNED_ACCESS
> > in a way that uses only internal state to determine the value where
> > STRICT_ALIGNMENT
> > is essentially ignored. e.g. PowerPC and riscv.
> >
> > The code generation *might* change for them but the tests won't run. I see
> > now way to
> > make the test accurate (as in, runs in all cases where the codegen changed)
> > unless I expose SLOW_UNALIGNED_ACCESS as a define so I can test for it.
> >
> > Would this be the way to go?
>
> I don't think so. SLOW_UNALIGNED_ACCESS is per mode and specific to
> a certain alignment.
>
Ah, right! that slipped my mind for a bit.
Ok for trunk?
Thanks for the review,
Tamar
diff --git a/gcc/doc/sourcebuild.texi b/gcc/doc/sourcebuild.texi
index 1646d0a99911aa7b2e66762e5907fbb0454ed00d..3b200964462a82ebbe68bbe798cc91ed27337034 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 word_mode_no_slow_unalign
+Target does not have slow unaligned access when doing word size accesses.
@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..17b956022e4efb37044c7a74cc8baa9fb779221a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/struct-simple.c
@@ -0,0 +1,52 @@
+/* { dg-do-run } */
+/* { dg-require-effective-target word_mode_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..03413c323d00e88872879a741ab3c015e052311d 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -6037,6 +6037,31 @@ proc check_effective_target_unaligned_stack { } {
return $et_unaligned_stack_saved
}
+# Return 1 if the target plus current options does not have
+# slow unaligned access when using word size accesses.
+#
+# This won't change for different subtargets so cache the result.
+
+proc check_effective_target_word_mode_no_slow_unalign { } {
+ global et_word_mode_no_slow_unalign_saved
+ global et_index
+
+ if [info exists et_word_mode_no_slow_unalign_saved($et_index)] {
+ verbose "check_effective_target_word_mode_no_slow_unalign: \
+ using cached result" 2
+ } else {
+ set et_word_mode_no_slow_unalign_saved($et_index) 0
+ if { [is-effective-target non_strict_align]
+ && !([istarget arm*-*-*])
+ } {
+ set et_word_mode_no_slow_unalign_saved($et_index) 1
+ }
+ }
+ verbose "check_effective_target_word_mode_no_slow_unalign:\
+ returning $et_word_mode_no_slow_unalign_saved($et_index)" 2
+ return $et_word_mode_no_slow_unalign_saved($et_index)
+}
+
# Return 1 if the target plus current options does not support a vector
# alignment mechanism, 0 otherwise.
#
