From 4e2a2d6ad2d1bfe1269bc78da4251814505eb42e Mon Sep 17 00:00:00 2001
From: Pan Li <pan2.li@intel.com>
Date: Fri, 26 Sep 2025 23:08:20 +0800
Subject: [PATCH] RISC-V: Combine vec_duplicate + vwaddu.wv to vwaddu.wx on
 GR2VR cost

This patch would like to combine the vec_duplicate + vwaddu.wv to the
vwaddu.wx.  From example as below code.  The related pattern will depend
on the cost of vec_duplicate from GR2VR.  Then the late-combine will
take action if the cost of GR2VR is zero, and reject the combination
if the GR2VR cost is greater than zero.

Assume we have asm code like below, GR2VR cost is 0.

Before this patch:
  11       beq a3,zero,.L8
  12       vsetvli a5,zero,e32,m1,ta,ma
  13       vmv.v.x v2,a2
  ...
  16   .L3:
  17       vsetvli a5,a3,e32,m1,ta,ma
  ...
  22       vwaddu.wv v1,v2,v3
  ...
  25       bne a3,zero,.L3

After this patch:
  11       beq a3,zero,.L8
  ...
  14    .L3:
  15       vsetvli a5,a3,e32,m1,ta,ma
  ...
  20       vwaddu.wx v1,a2,v3
  ...
  23       bne a3,zero,.L3

Unfortunately, and similar as vwaddu.vv, only widening from uint32_t to
uint64_t has the necessary zero-extend during combine, we loss the extend
op after expand for any other types.

gcc/ChangeLog:

	* config/riscv/autovec-opt.md (*widen_waddu_wx_<mode>): Add new
	pattern to match vwaddu.wx.

Signed-off-by: Pan Li <pan2.li@intel.com>
---
 gcc/config/riscv/autovec-opt.md | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/gcc/config/riscv/autovec-opt.md b/gcc/config/riscv/autovec-opt.md
index a5eb49cc81e..d5950ebe3b6 100644
--- a/gcc/config/riscv/autovec-opt.md
+++ b/gcc/config/riscv/autovec-opt.md
@@ -1911,6 +1911,26 @@
   }
   [(set_attr "type" "viwalu")])
 
+(define_insn_and_split "*widen_waddu_wx_<mode>"
+ [(set (match_operand:VWEXTI_D       0 "register_operand")
+       (any_widen_binop:VWEXTI_D
+	 (vec_duplicate:VWEXTI_D
+	   (any_extend:<VEL>
+	     (match_operand:<VSUBEL> 2 "register_operand")))
+	   (match_operand:VWEXTI_D   1 "register_operand")))]
+  "TARGET_VECTOR && TARGET_64BIT && can_create_pseudo_p ()"
+  "#"
+  "&& 1"
+  [(const_int 0)]
+  {
+    insn_code icode = code_for_pred_single_widen_scalar (PLUS, ZERO_EXTEND,
+							 <MODE>mode);
+    riscv_vector::emit_vlmax_insn (icode, riscv_vector::BINARY_OP, operands);
+
+    DONE;
+  }
+  [(set_attr "type" "viwalu")])
+
 ;; =============================================================================
 ;; Combine vec_duplicate + op.vv to op.vf
 ;; Include
-- 
2.47.3