2019-03-05  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	PR middle-end/89544
	* function.c (use_register_for_decl): Avoid using unaligned stack
	values on strict alignment targets.
	(assign_parm_find_stack_rtl): Use larger alignment when possible.

testsuite:
2019-03-05  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	PR middle-end/89544
	* gcc.target/arm/unaligned-argument-1.c: New test.
	* gcc.target/arm/unaligned-argument-2.c: New test.

Index: gcc/function.c
===================================================================
--- gcc/function.c	(revision 269264)
+++ gcc/function.c	(working copy)
@@ -2210,6 +2210,12 @@ use_register_for_decl (const_tree decl)
   if (DECL_MODE (decl) == BLKmode)
     return false;
 
+  if (STRICT_ALIGNMENT && TREE_CODE (decl) == PARM_DECL
+      && DECL_INCOMING_RTL (decl) && MEM_P (DECL_INCOMING_RTL (decl))
+      && GET_MODE_ALIGNMENT (DECL_MODE (decl))
+	 > MEM_ALIGN (DECL_INCOMING_RTL (decl)))
+    return false;
+
   /* If -ffloat-store specified, don't put explicit float variables
      into registers.  */
   /* ??? This should be checked after DECL_ARTIFICIAL, but tree-ssa
@@ -2698,8 +2704,20 @@ assign_parm_find_stack_rtl (tree parm, struct assi
      intentionally forcing upward padding.  Otherwise we have to come
      up with a guess at the alignment based on OFFSET_RTX.  */
   poly_int64 offset;
-  if (data->locate.where_pad != PAD_DOWNWARD || data->entry_parm)
+  if (data->locate.where_pad == PAD_NONE || data->entry_parm)
     align = boundary;
+  else if (data->locate.where_pad == PAD_UPWARD)
+    {
+      align = boundary;
+      if (poly_int_rtx_p (offset_rtx, &offset)
+	  && STACK_POINTER_OFFSET == 0)
+	{
+	  unsigned int offset_align = known_alignment (offset) * BITS_PER_UNIT;
+	  if (offset_align == 0 || offset_align > STACK_BOUNDARY)
+	    offset_align = STACK_BOUNDARY;
+	  align = MAX (align, offset_align);
+	}
+    }
   else if (poly_int_rtx_p (offset_rtx, &offset))
     {
       align = least_bit_hwi (boundary);
Index: gcc/testsuite/gcc.target/arm/unaligned-argument-1.c
===================================================================
--- gcc/testsuite/gcc.target/arm/unaligned-argument-1.c	(revision 0)
+++ gcc/testsuite/gcc.target/arm/unaligned-argument-1.c	(working copy)
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-marm -march=armv6 -mno-unaligned-access -mfloat-abi=soft -mabi=aapcs -O3" } */
+
+struct s {
+  int a, b;
+} __attribute__((aligned(8)));
+
+struct s f0;
+
+void f(int a, int b, int c, int d, struct s f)
+{
+  f0 = f;
+}
+
+/* { dg-final { scan-assembler-times "stmdb" 0 } } */
+/* { dg-final { scan-assembler-times "ldrd\[^\\n\]*\\\[sp\\\]" 1 } } */
+/* { dg-final { scan-assembler-times "ldrd" 1 } } */
+/* { dg-final { scan-assembler-times "strd" 1 } } */
Index: gcc/testsuite/gcc.target/arm/unaligned-argument-2.c
===================================================================
--- gcc/testsuite/gcc.target/arm/unaligned-argument-2.c	(revision 0)
+++ gcc/testsuite/gcc.target/arm/unaligned-argument-2.c	(working copy)
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-marm -march=armv6 -mno-unaligned-access -mfloat-abi=soft -mabi=aapcs -O3" } */
+
+struct s {
+  int a, b;
+} __attribute__((aligned(8)));
+
+struct s f0;
+
+void f(int a, int b, int c, int d, int e, struct s f)
+{
+  f0 = f;
+}
+
+/* { dg-final { scan-assembler-times "stmdb" 1 } } */
+/* { dg-final { scan-assembler-times "ldrd\[^\\n\]*\\\[sp\\\]" 1 } } */
+/* { dg-final { scan-assembler-times "ldrd" 1 } } */
+/* { dg-final { scan-assembler-times "strd" 1 } } */