[gcc r14-6099] RISC-V: Robostify the W43, W86, W87 constraint enabled attribute

[Pan Li]

https://gcc.gnu.org/g:d3544cea63d0a642b6357a7be55986f5562beaa0

commit r14-6099-gd3544cea63d0a642b6357a7be55986f5562beaa0
Author: Juzhe-Zhong <juzhe.zhong@rivai.ai>
Date:   Mon Dec 4 06:47:41 2023 +0800

    RISC-V: Robostify the W43, W86, W87 constraint enabled attribute
    
    Committed as it is obvious fix.
    
    gcc/ChangeLog:
    
            * config/riscv/riscv.md: Rostify the constraints.

Diff:
---
 gcc/config/riscv/riscv.md | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/gcc/config/riscv/riscv.md b/gcc/config/riscv/riscv.md
index 4c6f63677df..ff521454876 100644
--- a/gcc/config/riscv/riscv.md
+++ b/gcc/config/riscv/riscv.md
@@ -515,13 +515,28 @@
 	      (match_test "riscv_get_v_regno_alignment (GET_MODE (operands[0])) != 2"))
 	 (const_string "no")
 
-         (and (eq_attr "group_overlap" "W42,W43")
+         (and (eq_attr "group_overlap" "W42")
 	      (match_test "riscv_get_v_regno_alignment (GET_MODE (operands[0])) != 4"))
 	 (const_string "no")
 
-         (and (eq_attr "group_overlap" "W84,W86,W87")
+         (and (eq_attr "group_overlap" "W84")
 	      (match_test "riscv_get_v_regno_alignment (GET_MODE (operands[0])) != 8"))
 	 (const_string "no")
+
+         ;; According to RVV ISA:
+         ;; The destination EEW is greater than the source EEW, the source EMUL is at least 1,
+	 ;; and the overlap is in the highest-numbered part of the destination register group
+	 ;; (e.g., when LMUL=8, vzext.vf4 v0, v6 is legal, but a source of v0, v2, or v4 is not).
+	 ;; So the source operand should have LMUL >= 1.
+         (and (eq_attr "group_overlap" "W43")
+	      (match_test "riscv_get_v_regno_alignment (GET_MODE (operands[0])) != 4
+			   && riscv_get_v_regno_alignment (GET_MODE (operands[3])) >= 1"))
+	 (const_string "no")
+
+         (and (eq_attr "group_overlap" "W86,W87")
+	      (match_test "riscv_get_v_regno_alignment (GET_MODE (operands[0])) != 8
+			   && riscv_get_v_regno_alignment (GET_MODE (operands[3])) >= 1"))
+	 (const_string "no")
         ]
        (const_string "yes")))