Fix ldrd offsets

Fix the ldrd offsets of Thumb-2 - for TARGET_LDRD the range is +-1020,
without -252..4096.  This reduces the number of addressing instructions
when using DI mode operations (such as in PR77308).

    gcc/
	* config/arm/arm.c (arm_legitimate_index_p): Add comment.
	(thumb2_legitimate_index_p): Use correct range for DI/DF mode.

From-SVN: r251681

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6f93a4b57b3bd9fcc5524396b5ad73db241af0c0..74bf4a07f98e89b922375d3fabff731312dd8c60 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2017-09-04  Wilco Dijkstra  <wdijkstr@arm.com>
+
+       * config/arm/arm.c (arm_legitimate_index_p): Add comment.
+       (thumb2_legitimate_index_p): Use correct range for DI/DF mode.
+
 2017-09-04  Bernd Edlinger  <bernd.edlinger@hotmail.de>
 
        PR target/77308

diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index e31ab608dd346d7bfd4e90b6cc8c9d5c03636808..487095785414531c3e3302932e5d17848b07a8c6 100644 (file)
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -7932,6 +7932,8 @@ arm_legitimate_index_p (machine_mode mode, rtx index, RTX_CODE outer,
        {
          HOST_WIDE_INT val = INTVAL (index);
 
+         /* Assume we emit ldrd or 2x ldr if !TARGET_LDRD.
+            If vldr is selected it uses arm_coproc_mem_operand.  */
          if (TARGET_LDRD)
            return val > -256 && val < 256;
          else
@@ -8059,11 +8061,13 @@ thumb2_legitimate_index_p (machine_mode mode, rtx index, int strict_p)
       if (code == CONST_INT)
        {
          HOST_WIDE_INT val = INTVAL (index);
-         /* ??? Can we assume ldrd for thumb2?  */
-         /* Thumb-2 ldrd only has reg+const addressing modes.  */
-         /* ldrd supports offsets of +-1020.
-            However the ldr fallback does not.  */
-         return val > -256 && val < 256 && (val & 3) == 0;
+         /* Thumb-2 ldrd only has reg+const addressing modes.
+            Assume we emit ldrd or 2x ldr if !TARGET_LDRD.
+            If vldr is selected it uses arm_coproc_mem_operand.  */
+         if (TARGET_LDRD)
+           return IN_RANGE (val, -1020, 1020) && (val & 3) == 0;
+         else
+           return IN_RANGE (val, -255, 4095 - 4);
        }
       else
        return 0;