From eb49bbb886ef374eddb93e866c9c9f5f314c8014 Mon Sep 17 00:00:00 2001
From: Richard Sandiford <richard.sandiford@arm.com>
Date: Tue, 18 Jun 2024 12:22:31 +0100
Subject: [PATCH 13/16] aarch64: Add some uses of force_lowpart_subreg

This patch makes more use of force_lowpart_subreg, similarly
to the recent patch for force_subreg.  The criteria were:

(1) The code is obviously specific to expand (where new pseudos
    can be created).

(2) The value is obviously an rvalue rather than an lvalue.

gcc/
	PR target/115464
	* config/aarch64/aarch64-builtins.cc (aarch64_expand_fcmla_builtin)
	(aarch64_expand_rwsr_builtin): Use force_lowpart_subreg instead of
	simplify_gen_subreg and lowpart_subreg.
	* config/aarch64/aarch64-sve-builtins-base.cc
	(svset_neonq_impl::expand): Likewise.
	* config/aarch64/aarch64-sve-builtins-sme.cc
	(add_load_store_slice_operand): Likewise.
	* config/aarch64/aarch64.cc (aarch64_sve_reinterpret): Likewise.
	(aarch64_addti_scratch_regs, aarch64_subvti_scratch_regs): Likewise.

gcc/testsuite/
	PR target/115464
	* gcc.target/aarch64/sve/acle/general/pr115464_2.c: New test.

(cherry picked from commit 6bd4fbae45d11795a9a6f54b866308d4d7134def)
---
 gcc/config/aarch64/aarch64-builtins.cc             | 11 +++++------
 gcc/config/aarch64/aarch64-sve-builtins-base.cc    |  2 +-
 gcc/config/aarch64/aarch64-sve-builtins-sme.cc     |  2 +-
 gcc/config/aarch64/aarch64.cc                      | 14 +++++---------
 .../aarch64/sve/acle/general/pr115464_2.c          | 11 +++++++++++
 5 files changed, 23 insertions(+), 17 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/aarch64/sve/acle/general/pr115464_2.c

diff --git a/gcc/config/aarch64/aarch64-builtins.cc b/gcc/config/aarch64/aarch64-builtins.cc
index b2e46a073a8..264b9560709 100644
--- a/gcc/config/aarch64/aarch64-builtins.cc
+++ b/gcc/config/aarch64/aarch64-builtins.cc
@@ -2497,8 +2497,7 @@ aarch64_expand_fcmla_builtin (tree exp, rtx target, int fcode)
   int lane = INTVAL (lane_idx);
 
   if (lane < nunits / 4)
-    op2 = simplify_gen_subreg (d->mode, op2, quadmode,
-			       subreg_lowpart_offset (d->mode, quadmode));
+    op2 = force_lowpart_subreg (d->mode, op2, quadmode);
   else
     {
       /* Select the upper 64 bits, either a V2SF or V4HF, this however
@@ -2508,8 +2507,7 @@ aarch64_expand_fcmla_builtin (tree exp, rtx target, int fcode)
 	 gen_highpart_mode generates code that isn't optimal.  */
       rtx temp1 = gen_reg_rtx (d->mode);
       rtx temp2 = gen_reg_rtx (DImode);
-      temp1 = simplify_gen_subreg (d->mode, op2, quadmode,
-				   subreg_lowpart_offset (d->mode, quadmode));
+      temp1 = force_lowpart_subreg (d->mode, op2, quadmode);
       temp1 = force_subreg (V2DImode, temp1, d->mode, 0);
       if (BYTES_BIG_ENDIAN)
 	emit_insn (gen_aarch64_get_lanev2di (temp2, temp1, const0_rtx));
@@ -2754,7 +2752,7 @@ aarch64_expand_rwsr_builtin (tree exp, rtx target, int fcode)
 	case AARCH64_WSR64:
 	case AARCH64_WSRF64:
 	case AARCH64_WSR128:
-	  subreg = lowpart_subreg (sysreg_mode, input_val, mode);
+	  subreg = force_lowpart_subreg (sysreg_mode, input_val, mode);
 	  break;
 	case AARCH64_WSRF:
 	  subreg = gen_lowpart_SUBREG (SImode, input_val);
@@ -2789,7 +2787,8 @@ aarch64_expand_rwsr_builtin (tree exp, rtx target, int fcode)
     case AARCH64_RSR64:
     case AARCH64_RSRF64:
     case AARCH64_RSR128:
-      return lowpart_subreg (TYPE_MODE (TREE_TYPE (exp)), target, sysreg_mode);
+      return force_lowpart_subreg (TYPE_MODE (TREE_TYPE (exp)),
+				   target, sysreg_mode);
     case AARCH64_RSRF:
       subreg = gen_lowpart_SUBREG (SImode, target);
       return gen_lowpart_SUBREG (SFmode, subreg);
diff --git a/gcc/config/aarch64/aarch64-sve-builtins-base.cc b/gcc/config/aarch64/aarch64-sve-builtins-base.cc
index 2c95da79572..3c970e9c5f8 100644
--- a/gcc/config/aarch64/aarch64-sve-builtins-base.cc
+++ b/gcc/config/aarch64/aarch64-sve-builtins-base.cc
@@ -1183,7 +1183,7 @@ public:
     if (BYTES_BIG_ENDIAN)
       return e.use_exact_insn (code_for_aarch64_sve_set_neonq (mode));
     insn_code icode = code_for_vcond_mask (mode, mode);
-    e.args[1] = lowpart_subreg (mode, e.args[1], GET_MODE (e.args[1]));
+    e.args[1] = force_lowpart_subreg (mode, e.args[1], GET_MODE (e.args[1]));
     e.add_output_operand (icode);
     e.add_input_operand (icode, e.args[1]);
     e.add_input_operand (icode, e.args[0]);
diff --git a/gcc/config/aarch64/aarch64-sve-builtins-sme.cc b/gcc/config/aarch64/aarch64-sve-builtins-sme.cc
index f4c91bcbb95..b66b35ae60b 100644
--- a/gcc/config/aarch64/aarch64-sve-builtins-sme.cc
+++ b/gcc/config/aarch64/aarch64-sve-builtins-sme.cc
@@ -112,7 +112,7 @@ add_load_store_slice_operand (function_expander &e, insn_code icode,
   rtx base = e.args[argno];
   if (e.mode_suffix_id == MODE_vnum)
     {
-      rtx vnum = lowpart_subreg (SImode, e.args[vnum_argno], DImode);
+      rtx vnum = force_lowpart_subreg (SImode, e.args[vnum_argno], DImode);
       base = simplify_gen_binary (PLUS, SImode, base, vnum);
     }
   e.add_input_operand (icode, base);
diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
index 1beec94629d..a064aeecbc0 100644
--- a/gcc/config/aarch64/aarch64.cc
+++ b/gcc/config/aarch64/aarch64.cc
@@ -3284,7 +3284,7 @@ aarch64_sve_reinterpret (machine_mode mode, rtx x)
   /* can_change_mode_class must only return true if subregs and svreinterprets
      have the same semantics.  */
   if (targetm.can_change_mode_class (GET_MODE (x), mode, FP_REGS))
-    return lowpart_subreg (mode, x, GET_MODE (x));
+    return force_lowpart_subreg (mode, x, GET_MODE (x));
 
   rtx res = gen_reg_rtx (mode);
   x = force_reg (GET_MODE (x), x);
@@ -26979,9 +26979,8 @@ aarch64_addti_scratch_regs (rtx op1, rtx op2, rtx *low_dest,
 			    rtx *high_in2)
 {
   *low_dest = gen_reg_rtx (DImode);
-  *low_in1 = gen_lowpart (DImode, op1);
-  *low_in2 = simplify_gen_subreg (DImode, op2, TImode,
-				  subreg_lowpart_offset (DImode, TImode));
+  *low_in1 = force_lowpart_subreg (DImode, op1, TImode);
+  *low_in2 = force_lowpart_subreg (DImode, op2, TImode);
   *high_dest = gen_reg_rtx (DImode);
   *high_in1 = gen_highpart (DImode, op1);
   *high_in2 = simplify_gen_subreg (DImode, op2, TImode,
@@ -27013,11 +27012,8 @@ aarch64_subvti_scratch_regs (rtx op1, rtx op2, rtx *low_dest,
 			     rtx *high_in2)
 {
   *low_dest = gen_reg_rtx (DImode);
-  *low_in1 = simplify_gen_subreg (DImode, op1, TImode,
-				  subreg_lowpart_offset (DImode, TImode));
-
-  *low_in2 = simplify_gen_subreg (DImode, op2, TImode,
-				  subreg_lowpart_offset (DImode, TImode));
+  *low_in1 = force_lowpart_subreg (DImode, op1, TImode);
+  *low_in2 = force_lowpart_subreg (DImode, op2, TImode);
   *high_dest = gen_reg_rtx (DImode);
 
   *high_in1 = simplify_gen_subreg (DImode, op1, TImode,
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general/pr115464_2.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general/pr115464_2.c
new file mode 100644
index 00000000000..f561c34f732
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general/pr115464_2.c
@@ -0,0 +1,11 @@
+/* { dg-options "-O2" } */
+
+#include <arm_neon.h>
+#include <arm_sve.h>
+#include <arm_neon_sve_bridge.h>
+
+svuint16_t
+convolve4_4_x (uint16x8x2_t permute_tbl, svuint16_t a)
+{
+    return svset_neonq_u16 (a, permute_tbl.val[1]);
+}
-- 
2.44.2