[PATCH AArch64] Fix aarch64_simd_valid_immediate for Bigendian

[Alan Lawrence <alan dot lawrence at arm dot com>]

This patch fixes a bug whereby a vector like V8QImode {1,0,1,0,1,0,1,0} can 
result in an instruction like

movi v1.4h, 0x1

whereas on bigendian this should be

movi v1.4h, 0x1, lsl 8

Regression tested on aarch64_be-none-elf: no changes in libstdc++, newlib; no 
regressions in gcc or g++ and FAIL->PASS as listed below.

Ok for trunk (stage 4) ?

Cheers, Alan

gcc/ChangeLog:

2014-03-21  Alan Lawrence  alan.lawrence@arm.com

        * config/aarch64/aarch64.c (aarch64_simd_valid_immediate): reverse order
        of elements for bigendian.

=====
FAIL->PASS in gcc testsuite:

c-c++-common/cilk-plus/PS/reduction-1.c  -ftree-vectorize -fcilkplus -std=c99 
execution test
gcc.c-torture/execute/20000112-1.c execution,  -O0
gcc.c-torture/execute/900409-1.c execution,  -O0
gcc.c-torture/execute/p18298.c execution,  -O0
gcc.c-torture/execute/pr53645-2.c execution,  -O1
gcc.c-torture/execute/pr53645-2.c execution,  -O2
gcc.c-torture/execute/pr53645-2.c execution,  -O2 -flto
gcc.c-torture/execute/pr53645-2.c execution,  -O2 -flto -flto-partition=none
gcc.c-torture/execute/pr53645-2.c execution,  -O2 -flto -fno-use-linker-plugin 
-flto-partition=none
gcc.c-torture/execute/pr53645-2.c execution,  -O2 -flto -fuse-linker-plugin 
-fno-fat-lto-objects
gcc.c-torture/execute/pr53645-2.c execution,  -O3 -fomit-frame-pointer
gcc.c-torture/execute/pr53645-2.c execution,  -O3 -fomit-frame-pointer 
-funroll-all-loops -finline-functions
gcc.c-torture/execute/pr53645-2.c execution,  -O3 -fomit-frame-pointer 
-funroll-loops
gcc.c-torture/execute/pr53645-2.c execution,  -O3 -g
gcc.c-torture/execute/pr53645-2.c execution,  -Og -g
gcc.c-torture/execute/pr53645-2.c execution,  -Os
gcc.c-torture/execute/pr53645.c execution,  -O1
gcc.c-torture/execute/pr53645.c execution,  -O2
gcc.c-torture/execute/pr53645.c execution,  -O2 -flto
gcc.c-torture/execute/pr53645.c execution,  -O2 -flto -flto-partition=none
gcc.c-torture/execute/pr53645.c execution,  -O2 -flto -fno-use-linker-plugin 
-flto-partition=none
gcc.c-torture/execute/pr53645.c execution,  -O2 -flto -fuse-linker-plugin 
-fno-fat-lto-objects
gcc.c-torture/execute/pr53645.c execution,  -O3 -fomit-frame-pointer
gcc.c-torture/execute/pr53645.c execution,  -O3 -fomit-frame-pointer 
-funroll-all-loops -finline-functions
gcc.c-torture/execute/pr53645.c execution,  -O3 -fomit-frame-pointer -funroll-loops
gcc.c-torture/execute/pr53645.c execution,  -O3 -g
gcc.c-torture/execute/pr53645.c execution,  -Og -g

FAIL->PASS in g++ testsuite:

g++.dg/torture/pr37922.C  -O3 -fomit-frame-pointer  execution test
g++.dg/torture/pr37922.C  -O3 -fomit-frame-pointer -funroll-loops  execution test
g++.dg/torture/pr37922.C  -O3 -fomit-frame-pointer -funroll-all-loops 
-finline-functions  execution test
g++.dg/torture/pr37922.C  -O3 -g  execution test
g++.dg/torture/pr37922.C  -O3 -fomit-frame-pointer  execution test
g++.dg/torture/pr37922.C  -O3 -fomit-frame-pointer -funroll-loops  execution test
g++.dg/torture/pr37922.C  -O3 -fomit-frame-pointer -funroll-all-loops 
-finline-functions  execution test
g++.dg/torture/pr37922.C  -O3 -g  execution test

diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index f24b248..3166ebd 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -6563,7 +6563,9 @@ aarch64_simd_valid_immediate (rtx op, enum machine_mode mode, bool inverse,
   /* Splat vector constant out into a byte vector.  */
   for (i = 0; i < n_elts; i++)
     {
-      rtx el = CONST_VECTOR_ELT (op, i);
+      /* The vector is provided in gcc endian-neutral fashion.  For aarch64_be,
+         it must be laid out in the vector register in reverse order.  */
+      rtx el = CONST_VECTOR_ELT (op, BYTES_BIG_ENDIAN ? (n_elts - 1 - i) : i);
       unsigned HOST_WIDE_INT elpart;
       unsigned int part, parts;