RISC-V: Fix vsetvl compatibility predicate [PR118154].

In PR118154 we emit strided stores but the first of those does not
always have the proper VTYPE.  That's because we erroneously delete
a necessary vsetvl.

In order to determine whether to elide

(1)
      Expr[7]: VALID (insn 116, bb 17)
        Demand fields: demand_ratio_and_ge_sew demand_avl
        SEW=8, VLMUL=mf2, RATIO=16, MAX_SEW=64
        TAIL_POLICY=agnostic, MASK_POLICY=agnostic
        AVL=(reg:DI 0 zero)

when e.g.

(2)
      Expr[3]: VALID (insn 360, bb 15)
        Demand fields: demand_sew_lmul demand_avl
        SEW=64, VLMUL=m1, RATIO=64, MAX_SEW=64
        TAIL_POLICY=agnostic, MASK_POLICY=agnostic
        AVL=(reg:DI 0 zero)
        VL=(reg:DI 13 a3 [345])

is already available, we use
sew_ge_and_prev_sew_le_next_max_sew_and_next_ratio_valid_for_prev_sew_p.

(1) requires RATIO = SEW/LMUL = 16 and an SEW >= 8.  (2) has ratio = 64,
though, so we cannot directly elide (1).

This patch uses ratio_eq_p instead of next_ratio_valid_for_prev_sew_p.

	PR target/118154

gcc/ChangeLog:

	* config/riscv/riscv-vsetvl.cc (MAX_LMUL): New define.
	(pre_vsetvl::earliest_fuse_vsetvl_info): Use.
	(pre_vsetvl::pre_global_vsetvl_info): New predicate with equal
	ratio.
	* config/riscv/riscv-vsetvl.def: Use.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/pr118154-1.c: New test.
	* gcc.target/riscv/rvv/autovec/pr118154-2.c: New test.

2 files changed, 54 insertions, 0 deletions

diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr118154-1.c b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr118154-1.c
new file mode 100644
index 0000000..5538656
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr118154-1.c
@@ -0,0 +1,23 @@
+/* { dg-do run } */
+/* { dg-require-effective-target riscv_v_ok } */
+/* { dg-add-options riscv_v } */
+/* { dg-additional-options "-std=gnu99 -Wno-pedantic" } */
+
+long a;
+char b;
+char c[22][484];
+int main() {
+  for (int e = 4; e < 33; e++) {
+    for (int f = 0; f < 3; f++)
+      for (int g = 0; g < 18; g++) {
+        c[f][g * 22] = 1;
+        a = ({ a > 1 ? a : 1; });
+      }
+    for (int i = 0; i < 33; i++)
+      for (int h = 0; h < 6; h++)
+        for (int j = 0; j < 17; j++)
+          b = ({ b > 17 ? b : 17; });
+  }
+  if (c[1][44] != 1)
+    __builtin_abort ();
+}
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr118154-2.c b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr118154-2.c
new file mode 100644
index 0000000..4172f29
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr118154-2.c
@@ -0,0 +1,31 @@
+/* { dg-do run } */
+/* { dg-require-effective-target riscv_v_ok } */
+/* { dg-add-options riscv_v } */
+/* { dg-additional-options "-std=gnu99 -Wno-pedantic" } */
+
+long a;
+signed char b;
+long long d;
+signed char c[22][22][484];
+void m(long long *l, int n) { *l ^= n + (*l >> 2); }
+int main() {
+  signed char l = 35;
+  for (signed char f = 4; f; f++) {
+    for (signed g = 0; g < 022; g += 4)
+      for (signed char h = 0; h < 022; h++) {
+        c[9][g][h * 22 + h] = l;
+        a = ({ a > 4095 ? a : 4095; });
+      }
+    for (int i = 0; i < 22; i += 3)
+      for (signed char j = 1; j; j++)
+        for (signed char k = 0; k < 022; k++)
+          b = ({ b > 19 ? b : 19; });
+  }
+  for (long f = 0; f < 22; ++f)
+    for (long g = 0; g < 22; ++g)
+      for (long h = 0; h < 22; ++h)
+        for (long i = 0; i < 22; ++i)
+          m(&d, c[f][g][h * 2 + i]);
+  if (d != 38)
+    __builtin_abort ();
+}