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Re: [PATCHv3] Fix not 8-byte aligned ldrd/strd on ARMv5 (PR 89544)


On 7/31/19 3:16 PM, Richard Earnshaw (lists) wrote:
> 
> 
> On 30/07/2019 21:51, Bernd Edlinger wrote:
>> +/* { dg-options "-marm -march=armv6 -mno-unaligned-access -mfloat-abi=soft -mabi=aapcs -O3" } */
> 
> This isn't going to work as-is, we test many combinations of the compiler, either with explicit dejagnu settings or with the compiler defaults and the dejagnu settings can't generally be overridden this way.
> 
> For -marm you require an effective-target of arm_arm_ok.  For ldrd, it should be enough to just require an effective-target of arm_ldrd_strd_ok, then you can .
> 
> I don't think we really care about any ABIs other than aapcs, so I'd just leave that off.  And as for setting the float-abi, I don't see anything in the tests that would require that, so that can probably be omitted as well.
> 
> I think with all this, you can then write something like
> 
> /* { dg-require-effective-target arm_arm_ok && arm_ldrd_strd_ok } */
> /* { dg-options "-marm -mno-unaligned-access -O3 } */
> 
> But I haven't tested that, so you might need to fiddle with it a bit, especially the effective-target rule.
> 

Okay, it seems we need two dg-require-effective-target rules for this to work,
as in the attached new version of the patch which I am currently boot-strapping.

Is it OK for trunk after successful boot-strap and reg-testing?


Thanks
Bernd.
2019-07-30  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	PR middle-end/89544
	* function.c (assign_param_data_one): Remove unused data members.
	(assign_parm_find_stack_rtl): Use larger alignment when possible.
	(assign_parm_adjust_stack_rtl): Revise STRICT_ALIGNMENT check.
	(assign_parm_setup_reg): Handle misaligned stack arguments.

testsuite:
2019-07-30  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 273767)
+++ gcc/function.c	(working copy)
@@ -2274,8 +2274,6 @@ struct assign_parm_data_one
   int partial;
   BOOL_BITFIELD named_arg : 1;
   BOOL_BITFIELD passed_pointer : 1;
-  BOOL_BITFIELD on_stack : 1;
-  BOOL_BITFIELD loaded_in_reg : 1;
 };
 
 /* A subroutine of assign_parms.  Initialize ALL.  */
@@ -2699,8 +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);
@@ -2813,8 +2826,9 @@ assign_parm_adjust_stack_rtl (struct assign_parm_d
      ultimate type, don't use that slot after entry.  We'll make another
      stack slot, if we need one.  */
   if (stack_parm
-      && ((STRICT_ALIGNMENT
-	   && GET_MODE_ALIGNMENT (data->nominal_mode) > MEM_ALIGN (stack_parm))
+      && ((GET_MODE_ALIGNMENT (data->nominal_mode) > MEM_ALIGN (stack_parm)
+	   && targetm.slow_unaligned_access (data->nominal_mode,
+					     MEM_ALIGN (stack_parm)))
 	  || (data->nominal_type
 	      && TYPE_ALIGN (data->nominal_type) > MEM_ALIGN (stack_parm)
 	      && MEM_ALIGN (stack_parm) < PREFERRED_STACK_BOUNDARY)))
@@ -3292,6 +3306,23 @@ assign_parm_setup_reg (struct assign_parm_data_all
 
       did_conversion = true;
     }
+  else if (MEM_P (data->entry_parm)
+	   && GET_MODE_ALIGNMENT (promoted_nominal_mode)
+	      > MEM_ALIGN (data->entry_parm)
+	   && targetm.slow_unaligned_access (promoted_nominal_mode,
+					     MEM_ALIGN (data->entry_parm)))
+    {
+      enum insn_code icode = optab_handler (movmisalign_optab,
+					    promoted_nominal_mode);
+
+      if (icode != CODE_FOR_nothing)
+	emit_insn (GEN_FCN (icode) (parmreg, validated_mem));
+      else
+	rtl = parmreg = extract_bit_field (validated_mem,
+			GET_MODE_BITSIZE (promoted_nominal_mode), 0,
+			unsignedp, parmreg,
+			promoted_nominal_mode, VOIDmode, false, NULL);
+    }
   else
     emit_move_insn (parmreg, validated_mem);
 
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 +1,19 @@
+/* { 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	(working copy)
@@ -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 } } */

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