195 lines
7.3 KiB
Diff
195 lines
7.3 KiB
Diff
From ad5bf450aef2ffee6d57ed193fabc5f72f8eaa65 Mon Sep 17 00:00:00 2001
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From: rearnsha <rearnsha@138bc75d-0d04-0410-961f-82ee72b054a4>
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Date: Thu, 19 Oct 2017 13:16:42 +0000
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Subject: [PATCH] [ARM] PR 82445 - suppress 32-bit aligned ldrd/strd peepholing
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with -mno-unaligned-access
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Peephole patterns exist in the arm backend to spot load/store
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operations to adjacent memory operations in order to convert them into
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ldrd/strd instructions. However, when we have strict alignment
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enforced, then we can only do this if the accesses are known to be
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64-bit aligned; this is unlikely to be the case for most loads. The
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patch adds some alignment checking to the code that validates the
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addresses for use in the peephole patterns. This should also fix
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incorrect generation of ldrd/strd with unaligned accesses that could
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previously have occurred on ARMv5e where all such operations must be
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64-bit aligned.
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I've added some new tests as well. In doing so I discovered that the
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ldrd/strd peephole tests could never fail since they would match the
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source file name in the scanned assembly as well as any instructions
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of the intended type. I've fixed those by tightening the scan results
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slightly.
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gcc:
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* config/arm/arm.c (align_ok_ldrd_strd): New function.
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(mem_ok_for_ldrd_strd): New parameter align. Extract the alignment of the
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mem into it.
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(gen_operands_ldrd_strd): Validate the alignment of the accesses.
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testsuite:
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* gcc.target/arm/peep-ldrd-1.c: Tighten test scan pattern.
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* gcc.target/arm/peep-strd-1.c: Likewise.
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* gcc.target/arm/peep-ldrd-2.c: New test.
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* gcc.target/arm/peep-strd-2.c: New test.
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git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-6-branch@253892 138bc75d-0d04-0410-961f-82ee72b054a4
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---
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Upstream-Status: Backport
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Signed-off-by: Khem Raj <raj.khem@gmail.com>
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gcc/ChangeLog | 8 +++++++
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gcc/config/arm/arm.c | 27 ++++++++++++++++++----
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gcc/testsuite/ChangeLog | 8 +++++++
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gcc/testsuite/gcc.target/arm/peep-ldrd-1.c | 2 +-
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.../arm/{peep-ldrd-1.c => peep-ldrd-2.c} | 4 ++--
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gcc/testsuite/gcc.target/arm/peep-strd-1.c | 2 +-
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.../arm/{peep-strd-1.c => peep-strd-2.c} | 4 ++--
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7 files changed, 44 insertions(+), 11 deletions(-)
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copy gcc/testsuite/gcc.target/arm/{peep-ldrd-1.c => peep-ldrd-2.c} (63%)
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copy gcc/testsuite/gcc.target/arm/{peep-strd-1.c => peep-strd-2.c} (58%)
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diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
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index 9c0813d598d..e3da9f77fb6 100644
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--- a/gcc/config/arm/arm.c
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+++ b/gcc/config/arm/arm.c
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@@ -15926,12 +15926,23 @@ operands_ok_ldrd_strd (rtx rt, rtx rt2, rtx rn, HOST_WIDE_INT offset,
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return true;
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}
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+/* Return true if a 64-bit access with alignment ALIGN and with a
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+ constant offset OFFSET from the base pointer is permitted on this
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+ architecture. */
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+static bool
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+align_ok_ldrd_strd (HOST_WIDE_INT align, HOST_WIDE_INT offset)
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+{
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+ return (unaligned_access
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+ ? (align >= BITS_PER_WORD && (offset & 3) == 0)
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+ : (align >= 2 * BITS_PER_WORD && (offset & 7) == 0));
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+}
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+
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/* Helper for gen_operands_ldrd_strd. Returns true iff the memory
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operand MEM's address contains an immediate offset from the base
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- register and has no side effects, in which case it sets BASE and
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- OFFSET accordingly. */
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+ register and has no side effects, in which case it sets BASE,
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+ OFFSET and ALIGN accordingly. */
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static bool
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-mem_ok_for_ldrd_strd (rtx mem, rtx *base, rtx *offset)
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+mem_ok_for_ldrd_strd (rtx mem, rtx *base, rtx *offset, HOST_WIDE_INT *align)
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{
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rtx addr;
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@@ -15950,6 +15961,7 @@ mem_ok_for_ldrd_strd (rtx mem, rtx *base, rtx *offset)
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gcc_assert (MEM_P (mem));
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*offset = const0_rtx;
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+ *align = MEM_ALIGN (mem);
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addr = XEXP (mem, 0);
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@@ -15990,7 +16002,7 @@ gen_operands_ldrd_strd (rtx *operands, bool load,
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bool const_store, bool commute)
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{
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int nops = 2;
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- HOST_WIDE_INT offsets[2], offset;
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+ HOST_WIDE_INT offsets[2], offset, align[2];
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rtx base = NULL_RTX;
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rtx cur_base, cur_offset, tmp;
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int i, gap;
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@@ -16002,7 +16014,8 @@ gen_operands_ldrd_strd (rtx *operands, bool load,
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registers, and the corresponding memory offsets. */
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for (i = 0; i < nops; i++)
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{
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- if (!mem_ok_for_ldrd_strd (operands[nops+i], &cur_base, &cur_offset))
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+ if (!mem_ok_for_ldrd_strd (operands[nops+i], &cur_base, &cur_offset,
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+ &align[i]))
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return false;
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if (i == 0)
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@@ -16114,6 +16127,7 @@ gen_operands_ldrd_strd (rtx *operands, bool load,
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/* Swap the instructions such that lower memory is accessed first. */
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std::swap (operands[0], operands[1]);
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std::swap (operands[2], operands[3]);
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+ std::swap (align[0], align[1]);
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if (const_store)
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std::swap (operands[4], operands[5]);
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}
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@@ -16127,6 +16141,9 @@ gen_operands_ldrd_strd (rtx *operands, bool load,
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if (gap != 4)
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return false;
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+ if (!align_ok_ldrd_strd (align[0], offset))
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+ return false;
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+
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/* Make sure we generate legal instructions. */
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if (operands_ok_ldrd_strd (operands[0], operands[1], base, offset,
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false, load))
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diff --git a/gcc/testsuite/gcc.target/arm/peep-ldrd-1.c b/gcc/testsuite/gcc.target/arm/peep-ldrd-1.c
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index eb2b86ee7b6..d49eff6b87e 100644
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--- a/gcc/testsuite/gcc.target/arm/peep-ldrd-1.c
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+++ b/gcc/testsuite/gcc.target/arm/peep-ldrd-1.c
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@@ -8,4 +8,4 @@ int foo(int a, int b, int* p, int *q)
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*p = a;
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return a;
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}
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-/* { dg-final { scan-assembler "ldrd" } } */
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+/* { dg-final { scan-assembler "ldrd\\t" } } */
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diff --git a/gcc/testsuite/gcc.target/arm/peep-ldrd-1.c b/gcc/testsuite/gcc.target/arm/peep-ldrd-2.c
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similarity index 63%
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copy from gcc/testsuite/gcc.target/arm/peep-ldrd-1.c
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copy to gcc/testsuite/gcc.target/arm/peep-ldrd-2.c
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index eb2b86ee7b6..6822c2b1454 100644
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--- a/gcc/testsuite/gcc.target/arm/peep-ldrd-1.c
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+++ b/gcc/testsuite/gcc.target/arm/peep-ldrd-2.c
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@@ -1,6 +1,6 @@
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/* { dg-do compile } */
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/* { dg-require-effective-target arm_prefer_ldrd_strd } */
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-/* { dg-options "-O2" } */
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+/* { dg-options "-O2 -mno-unaligned-access" } */
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int foo(int a, int b, int* p, int *q)
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{
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a = p[2] + p[3];
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@@ -8,4 +8,4 @@ int foo(int a, int b, int* p, int *q)
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*p = a;
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return a;
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}
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-/* { dg-final { scan-assembler "ldrd" } } */
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+/* { dg-final { scan-assembler-not "ldrd\\t" } } */
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diff --git a/gcc/testsuite/gcc.target/arm/peep-strd-1.c b/gcc/testsuite/gcc.target/arm/peep-strd-1.c
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index bd330769599..fe1beac7229 100644
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--- a/gcc/testsuite/gcc.target/arm/peep-strd-1.c
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+++ b/gcc/testsuite/gcc.target/arm/peep-strd-1.c
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@@ -6,4 +6,4 @@ void foo(int a, int b, int* p)
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p[2] = a;
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p[3] = b;
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}
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-/* { dg-final { scan-assembler "strd" } } */
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+/* { dg-final { scan-assembler "strd\\t" } } */
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diff --git a/gcc/testsuite/gcc.target/arm/peep-strd-1.c b/gcc/testsuite/gcc.target/arm/peep-strd-2.c
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similarity index 58%
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copy from gcc/testsuite/gcc.target/arm/peep-strd-1.c
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copy to gcc/testsuite/gcc.target/arm/peep-strd-2.c
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index bd330769599..bfc5ebe9eec 100644
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--- a/gcc/testsuite/gcc.target/arm/peep-strd-1.c
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+++ b/gcc/testsuite/gcc.target/arm/peep-strd-2.c
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@@ -1,9 +1,9 @@
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/* { dg-do compile } */
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/* { dg-require-effective-target arm_prefer_ldrd_strd } */
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-/* { dg-options "-O2" } */
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+/* { dg-options "-O2 -mno-unaligned-access" } */
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void foo(int a, int b, int* p)
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{
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p[2] = a;
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p[3] = b;
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}
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-/* { dg-final { scan-assembler "strd" } } */
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+/* { dg-final { scan-assembler-not "strd\\t" } } */
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--
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2.15.0
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