[gcc r12-7138] aarch64: Remove redundant vec_concat patterns

[gcc r12-7138] aarch64: Remove redundant vec_concat patterns

[Richard Sandiford]

https://gcc.gnu.org/g:aeef5c57f161ad0258c5ab066ade2274bef3271a

commit r12-7138-gaeef5c57f161ad0258c5ab066ade2274bef3271a
Author: Richard Sandiford <richard.sandiford@arm.com>
Date:   Wed Feb 9 16:57:04 2022 +0000

    aarch64: Remove redundant vec_concat patterns
    
    move_lo_quad_internal_<mode> and move_lo_quad_internal_be_<mode>
    partially duplicate the later aarch64_combinez{,_be}<mode> patterns.
    The duplication itself is a regression.
    
    The only substantive differences between the two are:
    
    * combinez uses vector MOV (ORR) instead of element MOV (DUP).
      The former seems more likely to be handled via renaming.
    
    * combinez disparages the GPR->FPR alternative whereas move_lo_quad
      gave it equal cost.  The new test gives a token example of when
      the combinez behaviour helps.
    
    gcc/
            * config/aarch64/aarch64-simd.md (move_lo_quad_internal_<mode>)
            (move_lo_quad_internal_be_<mode>): Delete.
            (move_lo_quad_<mode>): Use aarch64_combine<Vhalf> instead of the above.
    
    gcc/testsuite/
            * gcc.target/aarch64/vec-init-8.c: New test.

Diff:
---
 gcc/config/aarch64/aarch64-simd.md            | 37 ++-------------------------
 gcc/testsuite/gcc.target/aarch64/vec-init-8.c | 15 +++++++++++
 2 files changed, 17 insertions(+), 35 deletions(-)

diff --git a/gcc/config/aarch64/aarch64-simd.md b/gcc/config/aarch64/aarch64-simd.md
index c5bc2ea658b..d6cd4c70fe7 100644
--- a/gcc/config/aarch64/aarch64-simd.md
+++ b/gcc/config/aarch64/aarch64-simd.md
@@ -1584,46 +1584,13 @@
 ;; On little-endian this is { operand, zeroes }
 ;; On big-endian this is { zeroes, operand }
 
-(define_insn "move_lo_quad_internal_<mode>"
-  [(set (match_operand:VQMOV 0 "register_operand" "=w,w,w")
-	(vec_concat:VQMOV
-	  (match_operand:<VHALF> 1 "register_operand" "w,r,r")
-	  (match_operand:<VHALF> 2 "aarch64_simd_or_scalar_imm_zero")))]
-  "TARGET_SIMD && !BYTES_BIG_ENDIAN"
-  "@
-   dup\\t%d0, %1.d[0]
-   fmov\\t%d0, %1
-   dup\\t%d0, %1"
-  [(set_attr "type" "neon_dup<q>,f_mcr,neon_dup<q>")
-   (set_attr "length" "4")
-   (set_attr "arch" "simd,fp,simd")]
-)
-
-(define_insn "move_lo_quad_internal_be_<mode>"
-  [(set (match_operand:VQMOV 0 "register_operand" "=w,w,w")
-	(vec_concat:VQMOV
-	  (match_operand:<VHALF> 2 "aarch64_simd_or_scalar_imm_zero")
-	  (match_operand:<VHALF> 1 "register_operand" "w,r,r")))]
-  "TARGET_SIMD && BYTES_BIG_ENDIAN"
-  "@
-   dup\\t%d0, %1.d[0]
-   fmov\\t%d0, %1
-   dup\\t%d0, %1"
-  [(set_attr "type" "neon_dup<q>,f_mcr,neon_dup<q>")
-   (set_attr "length" "4")
-   (set_attr "arch" "simd,fp,simd")]
-)
-
 (define_expand "move_lo_quad_<mode>"
   [(match_operand:VQMOV 0 "register_operand")
    (match_operand:<VHALF> 1 "register_operand")]
   "TARGET_SIMD"
 {
-  rtx zs = CONST0_RTX (<VHALF>mode);
-  if (BYTES_BIG_ENDIAN)
-    emit_insn (gen_move_lo_quad_internal_be_<mode> (operands[0], operands[1], zs));
-  else
-    emit_insn (gen_move_lo_quad_internal_<mode> (operands[0], operands[1], zs));
+  emit_insn (gen_aarch64_combine<Vhalf> (operands[0], operands[1],
+					 CONST0_RTX (<VHALF>mode)));
   DONE;
 }
 )
diff --git a/gcc/testsuite/gcc.target/aarch64/vec-init-8.c b/gcc/testsuite/gcc.target/aarch64/vec-init-8.c
new file mode 100644
index 00000000000..18f8afe10f5
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/vec-init-8.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+#include <arm_neon.h>
+
+int64x2_t f1(int64_t *ptr) {
+  int64_t x = *ptr;
+  asm volatile ("" ::: "memory");
+  if (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
+    return (int64x2_t) { 0, x };
+  else
+    return (int64x2_t) { x, 0 };
+}
+
+/* { dg-final { scan-assembler {\tldr\td0, \[x0\]\n} } } */