[PATCH] RISC-V: Fix bug reported by PR109535

[juzhe.zhong@rivai.ai]

From: Ju-Zhe Zhong <juzhe.zhong@rivai.ai>

Fix bug reported by google/highway who is using rvv intrinsic:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109535

        PR 109535

gcc/ChangeLog:

        * config/riscv/riscv-vsetvl.cc (count_regno_occurrences): New function.
        (pass_vsetvl::cleanup_insns): Fix bug.

gcc/testsuite/ChangeLog:

        * gcc.target/riscv/rvv/base/pr109535.c: New test.

---
 gcc/config/riscv/riscv-vsetvl.cc                  | 15 ++++++++++++++-
 .../gcc.target/riscv/rvv/base/pr109535.c          | 11 +++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.target/riscv/rvv/base/pr109535.c

diff --git a/gcc/config/riscv/riscv-vsetvl.cc b/gcc/config/riscv/riscv-vsetvl.cc
index 1b66e3b9eeb..b570b003a1e 100644
--- a/gcc/config/riscv/riscv-vsetvl.cc
+++ b/gcc/config/riscv/riscv-vsetvl.cc
@@ -1592,6 +1592,19 @@ backward_propagate_worthwhile_p (const basic_block cfg_bb,
   return true;
 }
 
+/* Count the number of REGNO in RINSN.  */
+static int
+count_regno_occurrences (rtx_insn *rinsn, unsigned int regno)
+{
+  int count = 0;
+  extract_insn (rinsn);
+  for (int i = 0; i < recog_data.n_operands; i++)
+    if (REG_P (recog_data.operand[i])
+	&& REGNO (recog_data.operand[i]) == regno)
+      count++;
+  return count;
+}
+
 avl_info::avl_info (const avl_info &other)
 {
   m_value = other.get_value ();
@@ -3924,7 +3937,7 @@ pass_vsetvl::cleanup_insns (void) const
 	  if (!has_vl_op (rinsn) || !REG_P (get_vl (rinsn)))
 	    continue;
 	  rtx avl = get_vl (rinsn);
-	  if (count_occurrences (PATTERN (rinsn), avl, 0) == 1)
+	  if (count_regno_occurrences (rinsn, REGNO (avl)) == 1)
 	    {
 	      /* Get the list of uses for the new instruction.  */
 	      auto attempt = crtl->ssa->new_change_attempt ();
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/pr109535.c b/gcc/testsuite/gcc.target/riscv/rvv/base/pr109535.c
new file mode 100644
index 00000000000..7582fe9c392
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/pr109535.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -march=rv32gcv -mabi=ilp32d" } */
+
+#include "riscv_vector.h"
+
+void foo(void *in1, void *in2, void *in3, void *out, size_t vl) {
+  vint8m1_t a = __riscv_vle8_v_i8m1(in1, vl);
+  vint8m1_t b = __riscv_vadd_vx_i8m1 (a, vl, vl);
+  __riscv_vse8_v_i8m1(out, b, vl);
+}
+
-- 
2.36.1