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Re: [PATCH: ARM] PR 45335 Use ldrd and strd to access two consecutive words


The patterns in original patch conflict with ldm2/stm2 patterns. In thumb2
ldrd/strd instructions are more flexible than ldm2/stm2, we don't have any
reason to continue to use ldm2/stm2. In this new patch I removed the thumb2
support of ldm2/stm2. The ldm2/stm2 with update patterns are not affected.

It passed testing on arm qemu.

thanks
Wei Guozhi


ChangeLog:
2010-08-24  Wei Guozhi  <carrot@google.com>

        PR target/45335
        * gcc/config/arm/thumb2.md (thumb2_ldrd, thumb2_ldrd_reg1,
        thumb2_ldrd_reg2 and peephole2): New insn pattern and related
        peephole2.
        (thumb2_strd, thumb2_strd_reg1, thumb2_strd_reg2 and peephole2):
        New insn pattern and related peephole2.
        * gcc/config/arm/arm.c (thumb2_legitimate_ldrd_p): New function.
        (thumb2_check_ldrd_operands): New function.
        * gcc/config/arm/arm-protos.h (thumb2_legitimate_ldrd_p): New prototype.
        (thumb2_check_ldrd_operands): New prototype.
        * gcc/config/arm/ldmstm.md (ldm2_ia, stm2_ia, ldm2_db, stm2_db):
        Change the ldm/stm patterns with 2 words to ARM only.
        * gcc/config/arm/constraints.md (Py): New thumb2 constant constraint
        suitable to ldrd/strd instructions.


2010-08-24  Wei Guozhi  <carrot@google.com>

        PR target/45335
        * gcc.target/arm/pr45335.c: New test.
        * gcc.target/arm/pr40457-1.c: Changed to load 3 words.
        * gcc.target/arm/pr40457-2.c: Changed to store 3 words.


Index: thumb2.md
===================================================================
--- thumb2.md   (revision 163363)
+++ thumb2.md   (working copy)
@@ -1257,3 +1257,147 @@
   "
   operands[2] = GEN_INT (32 - INTVAL (operands[2]));
   ")
+
+(define_insn "*thumb2_ldrd"
+  [(parallel [(set (match_operand:SI 0 "s_register_operand" "")
+                  (mem:SI (plus:SI
+                               (match_operand:SI 2 "s_register_operand" "rk")
+                               (match_operand:SI 3 "const_int_operand" "Py"))))
+             (set (match_operand:SI 1 "s_register_operand" "")
+                  (mem:SI (plus:SI (match_dup 2)
+                            (match_operand:SI 4 "const_int_operand" "Py"))))])]
+  "TARGET_THUMB2 && thumb2_check_ldrd_operands (operands[0], operands[1],
+                               operands[2], operands[3], operands[4], 1)"
+  "*
+  {
+    HOST_WIDE_INT offset1 = INTVAL (operands[3]);
+    HOST_WIDE_INT offset2 = INTVAL (operands[4]);
+    if (offset1 < offset2 )
+      return \"ldrd\\t%0, %1, [%2, %3]\";
+    else
+      return \"ldrd\\t%1, %0, [%2, %4]\";
+  }"
+)
+
+(define_insn "*thumb2_ldrd_reg1"
+  [(parallel [(set (match_operand:SI 0 "s_register_operand" "")
+                  (mem:SI (match_operand:SI 2 "s_register_operand" "rk")))
+             (set (match_operand:SI 1 "s_register_operand" "")
+                  (mem:SI (plus:SI (match_dup 2)
+                            (match_operand:SI 3 "const_int_operand" "Py"))))])]
+  "TARGET_THUMB2 && thumb2_check_ldrd_operands (operands[0], operands[1],
+                                               operands[2], 0, operands[3], 1)"
+  "*
+  {
+    HOST_WIDE_INT offset2 = INTVAL (operands[3]);
+    if (offset2 == 4)
+      return \"ldrd\\t%0, %1, [%2]\";
+    else
+      return \"ldrd\\t%1, %0, [%2, %3]\";
+  }"
+)
+
+(define_insn "*thumb2_ldrd_reg2"
+  [(parallel [(set (match_operand:SI 0 "s_register_operand" "")
+                  (mem:SI (plus:SI
+                               (match_operand:SI 2 "s_register_operand" "rk")
+                               (match_operand:SI 3 "const_int_operand" "Py"))))
+             (set (match_operand:SI 1 "s_register_operand" "")
+                  (mem:SI (match_dup 2)))])]
+  "TARGET_THUMB2 && thumb2_check_ldrd_operands (operands[0], operands[1],
+                                               operands[2], operands[3], 0, 1)"
+  "*
+  {
+    HOST_WIDE_INT offset1 = INTVAL (operands[3]);
+    if (offset1 == -4)
+      return \"ldrd\\t%0, %1, [%2, %3]\";
+    else
+      return \"ldrd\\t%1, %0, [%2]\";
+  }"
+)
+
+(define_peephole2
+  [(set (match_operand:SI 0 "s_register_operand" "")
+       (match_operand:SI 2 "memory_operand" ""))
+   (set (match_operand:SI 1 "s_register_operand" "")
+       (match_operand:SI 3 "memory_operand" ""))]
+  "TARGET_THUMB2 && thumb2_legitimate_ldrd_p (operands[0], operands[1],
+                                             operands[2], operands[3], 1)"
+  [(parallel [(set (match_operand:SI 0 "s_register_operand" "")
+                  (match_operand:SI 2 "memory_operand" ""))
+             (set (match_operand:SI 1 "s_register_operand" "")
+                  (match_operand:SI 3 "memory_operand" ""))])]
+  ""
+)
+
+(define_insn "*thumb2_strd"
+  [(parallel [(set (mem:SI
+                       (plus:SI (match_operand:SI 2 "s_register_operand" "rk")
+                                (match_operand:SI 3 "const_int_operand" "Py")))
+                  (match_operand:SI 0 "s_register_operand" ""))
+             (set (mem:SI (plus:SI (match_dup 2)
+                               (match_operand:SI 4 "const_int_operand" "Py")))
+                  (match_operand:SI 1 "s_register_operand" ""))])]
+  "TARGET_THUMB2 && thumb2_check_ldrd_operands (operands[0], operands[1],
+                               operands[2], operands[3], operands[4], 0)"
+  "*
+  {
+    HOST_WIDE_INT offset1 = INTVAL (operands[3]);
+    HOST_WIDE_INT offset2 = INTVAL (operands[4]);
+    if (offset1 < offset2 )
+      return \"strd\\t%0, %1, [%2, %3]\";
+    else
+      return \"strd\\t%1, %0, [%2, %4]\";
+  }"
+)
+
+(define_insn "*thumb2_strd_reg1"
+  [(parallel [(set (mem:SI (match_operand:SI 2 "s_register_operand" "rk"))
+                  (match_operand:SI 0 "s_register_operand" ""))
+             (set (mem:SI (plus:SI (match_dup 2)
+                               (match_operand:SI 3 "const_int_operand" "Py")))
+                  (match_operand:SI 1 "s_register_operand" ""))])]
+  "TARGET_THUMB2 && thumb2_check_ldrd_operands (operands[0], operands[1],
+                                               operands[2], 0, operands[3], 0)"
+  "*
+  {
+    HOST_WIDE_INT offset2 = INTVAL (operands[3]);
+    if (offset2 == 4)
+      return \"strd\\t%0, %1, [%2]\";
+    else
+      return \"strd\\t%1, %0, [%2, %3]\";
+  }"
+)
+
+(define_insn "*thumb2_strd_reg2"
+  [(parallel [(set (mem:SI (plus:SI
+                               (match_operand:SI 2 "s_register_operand" "rk")
+                               (match_operand:SI 3 "const_int_operand" "Py")))
+                  (match_operand:SI 0 "s_register_operand" ""))
+             (set (mem:SI (match_dup 2))
+                  (match_operand:SI 1 "s_register_operand" ""))])]
+  "TARGET_THUMB2 && thumb2_check_ldrd_operands (operands[0], operands[1],
+                                               operands[2], operands[3], 0, 0)"
+  "*
+  {
+    HOST_WIDE_INT offset1 = INTVAL (operands[3]);
+    if (offset1 == -4)
+      return \"strd\\t%0, %1, [%2, %3]\";
+    else
+      return \"strd\\t%1, %0, [%2]\";
+  }"
+)
+
+(define_peephole2
+  [(set (match_operand:SI 2 "memory_operand" "")
+       (match_operand:SI 0 "s_register_operand" ""))
+   (set (match_operand:SI 3 "memory_operand" "")
+       (match_operand:SI 1 "s_register_operand" ""))]
+  "TARGET_THUMB2 && thumb2_legitimate_ldrd_p (operands[0], operands[1],
+                                             operands[2], operands[3], 0)"
+  [(parallel [(set (match_operand:SI 2 "memory_operand" "")
+                  (match_operand:SI 0 "s_register_operand" ""))
+             (set (match_operand:SI 3 "memory_operand" "")
+                  (match_operand:SI 1 "s_register_operand" ""))])]
+  ""
+)
Index: arm.c
===================================================================
--- arm.c       (revision 163363)
+++ arm.c       (working copy)
@@ -22959,4 +22959,85 @@ arm_expand_sync (enum machine_mode mode,
     }
 }

+/* Check the legality of operands in an ldrd/strd instruction.  */
+bool
+thumb2_check_ldrd_operands (rtx reg1, rtx reg2, rtx base,
+                           rtx off1, rtx off2, bool ldrd)
+{
+  HOST_WIDE_INT offset1 = 0;
+  HOST_WIDE_INT offset2 = 0;
+
+  if (off1 != NULL)
+    offset1 = INTVAL (off1);
+  if (off2 != NULL)
+    offset2 = INTVAL (off2);
+
+  if (ldrd && (reg1 == reg2))
+    return false;
+
+  if ((offset1 + 4) == offset2)
+    return true;
+  if ((offset2 + 4) == offset1)
+    return true;
+
+  return false;
+}
+
+/* Check if the two memory accesses can be merged to an ldrd/strd instruction.
+   That is they use the same base register, and the gap between constant
+   offsets should be 4.  */
+bool
+thumb2_legitimate_ldrd_p (rtx reg1, rtx reg2, rtx mem1, rtx mem2, bool ldrd)
+{
+  rtx base1, base2, op1;
+  rtx addr1 = XEXP (mem1, 0);
+  rtx addr2 = XEXP (mem2, 0);
+  HOST_WIDE_INT offset1 = 0;
+  HOST_WIDE_INT offset2 = 0;
+
+  if (REG_P (addr1))
+    base1 = addr1;
+  else if (GET_CODE (addr1) == PLUS)
+    {
+      base1 = XEXP (addr1, 0);
+      op1 = XEXP (addr1, 1);
+      if (!REG_P (base1) || (GET_CODE (op1) != CONST_INT))
+        return false;
+      offset1 = INTVAL (op1);
+    }
+  else
+    return false;
+
+  if (REG_P (addr2))
+    base2 = addr2;
+  else if (GET_CODE (addr2) == PLUS)
+    {
+      base2 = XEXP (addr2, 0);
+      op1 = XEXP (addr2, 1);
+      if (!REG_P (base2) || (GET_CODE (op1) != CONST_INT))
+        return false;
+      offset2 = INTVAL (op1);
+    }
+  else
+    return false;
+
+  if (base1 != base2)
+    return false;
+
+  if ((offset1 > 1024) || (offset1 < -1020) || ((offset1 & 3) != 0))
+    return false;
+  if ((offset2 > 1024) || (offset2 < -1020) || ((offset2 & 3) != 0))
+    return false;
+
+  if (ldrd && ((reg1 == reg2) || (reg1 == base1)))
+    return false;
+
+  if ((offset1 + 4) == offset2)
+    return true;
+  if ((offset2 + 4) == offset1)
+    return true;
+
+  return false;
+}
+
 #include "gt-arm.h"
Index: arm-protos.h
===================================================================
--- arm-protos.h        (revision 163363)
+++ arm-protos.h        (working copy)
@@ -149,7 +149,8 @@ extern void arm_expand_sync (enum machin
 extern const char *arm_output_memory_barrier (rtx *);
 extern const char *arm_output_sync_insn (rtx, rtx *);
 extern unsigned int arm_sync_loop_insns (rtx , rtx *);
-
+extern bool thumb2_check_ldrd_operands (rtx, rtx, rtx, rtx, rtx, bool);
+extern bool thumb2_legitimate_ldrd_p (rtx, rtx, rtx, rtx, bool);
 extern bool arm_output_addr_const_extra (FILE *, rtx);

 #if defined TREE_CODE
Index: ldmstm.md
===================================================================
--- ldmstm.md   (revision 163363)
+++ ldmstm.md   (working copy)
@@ -852,7 +852,7 @@
      (set (match_operand:SI 2 "arm_hard_register_operand" "")
           (mem:SI (plus:SI (match_dup 3)
                   (const_int 4))))])]
-  "TARGET_32BIT && XVECLEN (operands[0], 0) == 2"
+  "TARGET_ARM && XVECLEN (operands[0], 0) == 2"
   "ldm%(ia%)\t%3, {%1, %2}"
   [(set_attr "type" "load2")
    (set_attr "predicable" "yes")])
@@ -901,7 +901,7 @@
           (match_operand:SI 1 "arm_hard_register_operand" ""))
      (set (mem:SI (plus:SI (match_dup 3) (const_int 4)))
           (match_operand:SI 2 "arm_hard_register_operand" ""))])]
-  "TARGET_32BIT && XVECLEN (operands[0], 0) == 2"
+  "TARGET_ARM && XVECLEN (operands[0], 0) == 2"
   "stm%(ia%)\t%3, {%1, %2}"
   [(set_attr "type" "store2")
    (set_attr "predicable" "yes")])
@@ -1041,7 +1041,7 @@
      (set (match_operand:SI 2 "arm_hard_register_operand" "")
           (mem:SI (plus:SI (match_dup 3)
                   (const_int -4))))])]
-  "TARGET_32BIT && XVECLEN (operands[0], 0) == 2"
+  "TARGET_ARM && XVECLEN (operands[0], 0) == 2"
   "ldm%(db%)\t%3, {%1, %2}"
   [(set_attr "type" "load2")
    (set_attr "predicable" "yes")])
@@ -1067,7 +1067,7 @@
           (match_operand:SI 1 "arm_hard_register_operand" ""))
      (set (mem:SI (plus:SI (match_dup 3) (const_int -4)))
           (match_operand:SI 2 "arm_hard_register_operand" ""))])]
-  "TARGET_32BIT && XVECLEN (operands[0], 0) == 2"
+  "TARGET_ARM && XVECLEN (operands[0], 0) == 2"
   "stm%(db%)\t%3, {%1, %2}"
   [(set_attr "type" "store2")
    (set_attr "predicable" "yes")])
Index: constraints.md
===================================================================
--- constraints.md      (revision 163363)
+++ constraints.md      (working copy)
@@ -31,7 +31,7 @@
 ;; The following multi-letter normal constraints have been used:
 ;; in ARM/Thumb-2 state: Da, Db, Dc, Dn, Dl, DL, Dv, Dy, Di
 ;; in Thumb-1 state: Pa, Pb, Pc, Pd
-;; in Thumb-2 state: Ps, Pt, Pu, Pv, Pw, Px
+;; in Thumb-2 state: Ps, Pt, Pu, Pv, Pw, Px, Py

 ;; The following memory constraints have been used:
 ;; in ARM/Thumb-2 state: Q, Ut, Uv, Uy, Un, Um, Us
@@ -189,6 +189,13 @@
   (and (match_code "const_int")
        (match_test "TARGET_THUMB2 && ival >= -7 && ival <= -1")))

+(define_constraint "Py"
+  "@internal In Thumb-2 state a constant that is a multiple of 4 in the
+   range -1020 to 1024"
+  (and (match_code "const_int")
+       (match_test "TARGET_THUMB2 && ival >= -1020 && ival <= 1024
+                   && (ival & 3) == 0")))
+
 (define_constraint "G"
  "In ARM/Thumb-2 state a valid FPA immediate constant."
  (and (match_code "const_double")



Index: pr40457-1.c
===================================================================
--- pr40457-1.c (revision 163363)
+++ pr40457-1.c (working copy)
@@ -1,9 +1,9 @@
-/* { dg-options "-Os" }  */
+/* { dg-options "-O2" }  */
 /* { dg-do compile } */

 int bar(int* p)
 {
-  int x = p[0] + p[1];
+  int x = p[0] + p[1] + p[2];
   return x;
 }

Index: pr40457-2.c
===================================================================
--- pr40457-2.c (revision 163363)
+++ pr40457-2.c (working copy)
@@ -5,6 +5,7 @@ void foo(int* p)
 {
   p[0] = 1;
   p[1] = 0;
+  p[2] = 2;
 }

 /* { dg-final { scan-assembler "stm" } } */
Index: pr45335.c
===================================================================
--- pr45335.c   (revision 0)
+++ pr45335.c   (revision 0)
@@ -0,0 +1,20 @@
+/* { dg-options "-mthumb -O2" } */
+/* { dg-require-effective-target arm_thumb2_ok } */
+/* { dg-final { scan-assembler "ldrd" } } */
+/* { dg-final { scan-assembler "strd" } } */
+
+struct S
+{
+    void* p1;
+    void* p2;
+    void* p3;
+    void* p4;
+};
+
+void foo1(struct S* fp, struct S* otherSaveArea)
+{
+    struct S* saveA = fp - 1;
+    printf("StackSaveArea for fp %p [%p/%p]:\n", fp, saveA, otherSaveArea);
+    printf("prevFrame=%p savedPc=%p meth=%p curPc=%p fp[0]=0x%08x\n",
+        saveA->p1, saveA->p2, saveA->p3, saveA->p4, *(unsigned int*)fp);
+}


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