[PATCHv5] Fix not 8-byte aligned ldrd/strd on ARMv5 (PR 89544)

[Bernd Edlinger <bernd.edlinger@hotmail.de>]

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On 8/15/19 6:29 PM, Richard Biener wrote:
>>>
>>> Please split it into the parts for the PR and parts making the
>>> asserts not trigger.
>>>
>>
>> Yes, will do.
>>

Okay, here is the rest of the PR 89544 fix,
actually just an optimization, making the larger stack alignment
known to the middle-end, and the test cases.


Boot-strapped and reg-tested on x86_64-pc-linux-gnu and arm-linux-gnueabihf.
Is it OK for trunk?


Thanks
Bernd.

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2019-08-15  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	PR middle-end/89544
	* function.c (assign_parm_find_stack_rtl): Use larger alignment
	when possible.

testsuite:
2019-08-15  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 274531)
+++ gcc/function.c	(Arbeitskopie)
@@ -2697,8 +2697,23 @@ 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 the argument offset is actually more aligned than the nominal
+	 stack slot boundary, take advantage of that excess alignment.
+	 Don't make any assumptions if STACK_POINTER_OFFSET is in use.  */
+      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	(Arbeitskopie)
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target arm_arm_ok } */
+/* { dg-require-effective-target arm_ldrd_strd_ok } */
+/* { dg-options "-marm -mno-unaligned-access -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 "ldrd" 1 } } */
+/* { dg-final { scan-assembler-times "strd" 1 } } */
+/* { dg-final { scan-assembler-times "stm" 0 } } */
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	(Arbeitskopie)
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target arm_arm_ok } */
+/* { dg-require-effective-target arm_ldrd_strd_ok } */
+/* { dg-options "-marm -mno-unaligned-access -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 "ldrd" 0 } } */
+/* { dg-final { scan-assembler-times "strd" 0 } } */
+/* { dg-final { scan-assembler-times "stm" 1 } } */