[AArch64_be] Don't fold reduction intrinsics.

gcc/

	* config/aarch64/aarch64-builtins.c
	(aarch64_gimple_fold_builtin): Don't fold reduction operations for
	BYTES_BIG_ENDIAN.

From-SVN: r213379

2 files changed, 20 insertions, 0 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b0ebfba..b2b6aa5 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,11 @@
 2014-07-31  James Greenhalgh  <james.greenhalgh@arm.com>
 
+	* config/aarch64/aarch64-builtins.c
+	(aarch64_gimple_fold_builtin): Don't fold reduction operations for
+	BYTES_BIG_ENDIAN.
+
+2014-07-31  James Greenhalgh  <james.greenhalgh@arm.com>
+
 	* config/aarch64/aarch64.c (aarch64_simd_vect_par_cnst_half): Vary
 	the generated mask based on BYTES_BIG_ENDIAN.
 	(aarch64_simd_check_vect_par_cnst_half): New.
diff --git a/gcc/config/aarch64/aarch64-builtins.c b/gcc/config/aarch64/aarch64-builtins.c
index fee17ec..58db77e 100644
--- a/gcc/config/aarch64/aarch64-builtins.c
+++ b/gcc/config/aarch64/aarch64-builtins.c
@@ -1383,6 +1383,20 @@ aarch64_gimple_fold_builtin (gimple_stmt_iterator *gsi)
   tree call = gimple_call_fn (stmt);
   tree fndecl;
   gimple new_stmt = NULL;
+
+  /* The operations folded below are reduction operations.  These are
+     defined to leave their result in the 0'th element (from the perspective
+     of GCC).  The architectural instruction we are folding will leave the
+     result in the 0'th element (from the perspective of the architecture).
+     For big-endian systems, these perspectives are not aligned.
+
+     It is therefore wrong to perform this fold on big-endian.  There
+     are some tricks we could play with shuffling, but the mid-end is
+     inconsistent in the way it treats reduction operations, so we will
+     end up in difficulty.  Until we fix the ambiguity - just bail out.  */
+  if (BYTES_BIG_ENDIAN)
+    return false;
+
   if (call)
     {
       fndecl = gimple_call_fndecl (stmt);