[arm] MVE: Relax addressing modes for full loads and stores

[Andre Vieira (lists) via Gcc-patches]

Hi Christophe,

This patch relaxes the addressing modes for the mve full load and stores 
(by full loads and stores I mean non-widening or narrowing loads and 
stores resp). The code before was requiring a LO_REGNUM for these, where 
this is only a requirement if the load is widening or the store narrowing.

So with this your patch should not be necessary.

Regression tested on arm-none-eabi-gcc.  Can you please confirm this 
fixes the issue you were seeing too?

gcc/ChangeLog:

        * config/arm/arm.h (MVE_STN_LDW_MODE): New MACRO.
        * config/arm/arm.c (mve_vector_mem_operand): Relax constraint on
        base register for non widening loads or narrowing stores.


Kind Regards,
Andre Vieiradiff --git a/gcc/config/arm/arm.h b/gcc/config/arm/arm.h
index 
dacce2b7f086eeffb0cd36b26f102f77130a92fa..f39786d0f9e19e81841a45f6d7e92e408272fe23
 100644
--- a/gcc/config/arm/arm.h
+++ b/gcc/config/arm/arm.h
@@ -1099,6 +1099,10 @@ extern const int arm_arch_cde_coproc_bits[];
   ((MODE) == V2DImode ||(MODE) == V4SImode || (MODE) == V8HImode \
    || (MODE) == V16QImode)
 
+/* Modes used in MVE's narrowing stores or widening loads.  */
+#define MVE_STN_LDW_MODE(MODE) \
+  ((MODE) == V4QImode || (MODE) == V8QImode || (MODE) == V4HImode)
+
 #define VALID_MVE_SF_MODE(MODE) \
   ((MODE) == V8HFmode || (MODE) == V4SFmode || (MODE) == V2DFmode)
 
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index 
bb75921f32df6185711d5304c044ce67a2d5671e..f5e09cb00b5478546d29c05cc885aeaa89501d39
 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -13438,27 +13438,28 @@ mve_vector_mem_operand (machine_mode mode, rtx op, 
bool strict)
          case E_V16QImode:
          case E_V8QImode:
          case E_V4QImode:
-           if (abs (val) <= 127)
-             return (reg_no < LAST_ARM_REGNUM && reg_no != SP_REGNUM)
-               || reg_no >= FIRST_PSEUDO_REGISTER;
-           return FALSE;
+           if (abs (val) > 127)
+             return FALSE;
+           break;
          case E_V8HImode:
          case E_V8HFmode:
          case E_V4HImode:
          case E_V4HFmode:
-           if (val % 2 == 0 && abs (val) <= 254)
-             return reg_no <= LAST_LO_REGNUM
-               || reg_no >= FIRST_PSEUDO_REGISTER;
-           return FALSE;
+           if (val % 2 != 0 || abs (val) > 254)
+             return FALSE;
+           break;
          case E_V4SImode:
          case E_V4SFmode:
-           if (val % 4 == 0 && abs (val) <= 508)
-             return (reg_no < LAST_ARM_REGNUM && reg_no != SP_REGNUM)
-               || reg_no >= FIRST_PSEUDO_REGISTER;
-           return FALSE;
+           if (val % 4 != 0 || abs (val) > 508)
+             return FALSE;
+           break;
          default:
            return FALSE;
        }
+      return reg_no >= FIRST_PSEUDO_REGISTER
+       || (MVE_STN_LDW_MODE (mode)
+           ? reg_no <= LAST_LO_REGNUM
+           : (reg_no < LAST_ARM_REGNUM && reg_no != SP_REGNUM));
     }
   return FALSE;
 }