[Patch PR target/67366 2/2] [gimple-fold.c] Support movmisalign optabs in gimple-fold.c

[Ramana Radhakrishnan]

This patch by Richard allows for movmisalign optabs to be supported
in gimple-fold.c. This caused a bit of pain in the testsuite with strlenopt-8.c
in conjunction with the ARM support for movmisalign_optabs as the test
was coded up to do different things depending on whether the target
supported misaligned access or not. However now with unaligned access
being allowed for different levels of the architecture in the arm backend,
the concept of the helper function non_strict_align mapping identically
to the definition of STRICT_ALIGNMENT disappears.

Adjusted thusly for ARM. The testsuite/lib changes were tested with an
arm-none-eabi multilib that included architecture variants that did not
support unaligned access and architecture variants that did.

The testing matrix for this patch was:

1. x86_64 bootstrap and regression test - no regressions.
2. armhf bootstrap and regression test - no regressions.
3. arm-none-eabi cross build and regression test for

{-marm/-march=armv7-a/-mfpu=vfpv3-d16/-mfloat-abi=softfp}
{-mthumb/-march=armv8-a/-mfpu=crypto-neon-fp-armv8/-mfloat-abi=hard}
{-marm/-mcpu=arm7tdmi/-mfloat-abi=soft}
{-mthumb/-mcpu=arm7tdmi/-mfloat-abi=soft}

with no regressions.

Ok to apply ?

Ramana

2015-10-08  Richard Biener  <rguenth@suse.de>

	* gimple-fold.c (optabs-query.h): Include
	(gimple_fold_builtin_memory_op): Allow unaligned stores
	when movmisalign_optabs are available.

2015-10-08  Ramana Radhakrishnan  <ramana.radhakrishnan@arm.com>

	PR target/67366
	* lib/target-supports.exp (check_effective_target_non_strict_align):
	Adjust for arm*-*-*.
	* gcc.target/arm/pr67366.c: New test.
---
 gcc/gimple-fold.c                      | 11 +++++++++--
 gcc/testsuite/gcc.target/arm/pr67366.c | 14 ++++++++++++++
 gcc/testsuite/lib/target-supports.exp  |  9 +++++++++
 3 files changed, 32 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/arm/pr67366.c

diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c
index a6caaa4..59d496b 100644
--- a/gcc/gimple-fold.c
+++ b/gcc/gimple-fold.c
@@ -63,6 +63,8 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-eh.h"
 #include "gimple-match.h"
 #include "gomp-constants.h"
+#include "optabs-query.h"
+
 
 /* Return true when DECL can be referenced from current unit.
    FROM_DECL (if non-null) specify constructor of variable DECL was taken from.
@@ -709,7 +711,9 @@ gimple_fold_builtin_memory_op (gimple_stmt_iterator *gsi,
 		  /* If the destination pointer is not aligned we must be able
 		     to emit an unaligned store.  */
 		  && (dest_align >= GET_MODE_ALIGNMENT (TYPE_MODE (type))
-		      || !SLOW_UNALIGNED_ACCESS (TYPE_MODE (type), dest_align)))
+		      || !SLOW_UNALIGNED_ACCESS (TYPE_MODE (type), dest_align)
+		      || (optab_handler (movmisalign_optab, TYPE_MODE (type))
+			  != CODE_FOR_nothing)))
 		{
 		  tree srctype = type;
 		  tree desttype = type;
@@ -721,7 +725,10 @@ gimple_fold_builtin_memory_op (gimple_stmt_iterator *gsi,
 		    srcmem = tem;
 		  else if (src_align < GET_MODE_ALIGNMENT (TYPE_MODE (type))
 			   && SLOW_UNALIGNED_ACCESS (TYPE_MODE (type),
-						     src_align))
+						     src_align)
+			   && (optab_handler (movmisalign_optab,
+					      TYPE_MODE (type))
+			       == CODE_FOR_nothing))
 		    srcmem = NULL_TREE;
 		  if (srcmem)
 		    {
diff --git a/gcc/testsuite/gcc.target/arm/pr67366.c b/gcc/testsuite/gcc.target/arm/pr67366.c
new file mode 100644
index 0000000..1e8b672
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/pr67366.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target arm_unaligned } */
+/* { dg-options "-O2" } */
+
+typedef unsigned int u32;
+u32
+read32 (const void* ptr)
+{
+  u32 v;
+  __builtin_memcpy (&v, ptr, sizeof(v));
+  return v;
+}
+
+/* { dg-final { scan-assembler "@ unaligned" } } */
diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index 9057a27..4d5b0a3d 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -6262,6 +6262,15 @@ proc check_vect_support_and_set_flags { } {
 # Return 1 if the target does *not* require strict alignment.
 
 proc check_effective_target_non_strict_align {} {
+
+    # On ARM, the default is to use STRICT_ALIGNMENT, but there
+    # are interfaces defined for misaligned access and thus
+    # depending on the architecture levels unaligned access is
+    # available.
+    if [istarget "arm*-*-*"] {
+	return [check_effective_target_arm_unaligned]
+    }
+
     return [check_no_compiler_messages non_strict_align assembly {
 	char *y;
 	typedef char __attribute__ ((__aligned__(__BIGGEST_ALIGNMENT__))) c;