[Patch PR target/67366 1/2] [ARM] - Add movmisalignhi / si patterns

[Ramana Radhakrishnan]

This adds movmisalignhi and movmisalignsi expanders when unaligned
access is allowed by the architecture. This allows the mid-end
to expand to misaligned loads and stored.

Compared code generated for the Linux kernel and
it changes code generation for a handful of files all for the better
basically by reducing the stack usage.

Tested by :

1. armhf bootstrap and regression test - no regressions.
2.. arm-none-eabi cross build and regression test for

    {-marm/-march=armv7-a/-mfpu=vfpv3-d16/-mfloat-abi=softfp}
    {-mthumb/-march=armv8-a/-mfpu=crypto-neon-fp-armv8/-mfloat-abi=hard}
    {-marm/-mcpu=arm7tdmi/-mfloat-abi=soft}
    {-mthumb/-mcpu=arm7tdmi/-mfloat-abi=soft}

Will apply to trunk once 2/2 is approved.

regards
Ramana

2015-09-15  Ramana Radhakrishnan  <ramana.radhakrish...@arm.com>

        PR target/67366
        * config/arm/arm.md (movmisalign<mode>): New.
        * config/arm/iterators.md (HSI): New.
---
 gcc/config/arm/arm.md       | 35 +++++++++++++++++++++++++++++++++++
 gcc/config/arm/iterators.md |  3 +++
 2 files changed, 38 insertions(+)

diff --git a/gcc/config/arm/arm.md b/gcc/config/arm/arm.md
index b4c555b..9a3f7bd 100644
--- a/gcc/config/arm/arm.md
+++ b/gcc/config/arm/arm.md
@@ -11506,6 +11506,41 @@
   }"
 )
 
+;; movmisalign patterns for HImode and SImode.
+(define_expand "movmisalign<mode>"
+  [(match_operand:HSI 0 "general_operand")
+   (match_operand:HSI 1 "general_operand")]
+  "unaligned_access"
+{
+  /* This pattern is not permitted to fail during expansion: if both arguments
+     are non-registers (e.g. memory := constant), force operand 1 into a
+     register.  */
+  rtx (* gen_unaligned_load)(rtx, rtx);
+  rtx tmp_dest = operands[0];
+  if (!s_register_operand (operands[0], <MODE>mode)
+      && !s_register_operand (operands[1], <MODE>mode))
+    operands[1] = force_reg (<MODE>mode, operands[1]);
+
+  if (<MODE>mode == HImode)
+   {
+    gen_unaligned_load = gen_unaligned_loadhiu;
+    tmp_dest = gen_reg_rtx (SImode);
+   }
+  else
+    gen_unaligned_load = gen_unaligned_loadsi;
+
+  if (MEM_P (operands[1]))
+   {
+    emit_insn (gen_unaligned_load (tmp_dest, operands[1]));
+    if (<MODE>mode == HImode)
+      emit_move_insn (operands[0], gen_lowpart (HImode, tmp_dest));
+   }
+  else
+    emit_insn (gen_unaligned_store<mode> (operands[0], operands[1]));
+
+  DONE;
+})
+
 ;; Vector bits common to IWMMXT and Neon
 (include "vec-common.md")
 ;; Load the Intel Wireless Multimedia Extension patterns
diff --git a/gcc/config/arm/iterators.md b/gcc/config/arm/iterators.md
index 47cc1ee..6a54125 100644
--- a/gcc/config/arm/iterators.md
+++ b/gcc/config/arm/iterators.md
@@ -33,6 +33,9 @@
 ;; A list of integer modes that are up to one word long
 (define_mode_iterator QHSI [QI HI SI])
 
+;; A list of integer modes that are half and one word long
+(define_mode_iterator HSI [HI SI])
+
 ;; A list of integer modes that are less than a word
 (define_mode_iterator NARROW [QI HI])
 
-- 
1.9.1