[PATCH v2] RISC-V: Fix ICE in riscv vector costs

[demin.han]

The following code can result in ICE:
-march=rv64gcv --param riscv-autovec-lmul=dynamic -O3

char *jpeg_difference7_input_buf;
void jpeg_difference7(int *diff_buf) {
  unsigned width;
  int samp, Rb;
  while (--width) {
    Rb = samp = *jpeg_difference7_input_buf;
    *diff_buf++ = -(int)(samp + (long)Rb >> 1);
  }
}

One biggest_mode update missed in one branch and trigger assertion fail.
gcc_assert (biggest_size >= mode_size);

Tested On RV64 and no regression.

        PR 114264

gcc/ChangeLog:

        * config/riscv/riscv-vector-costs.cc: Fix ICE

gcc/testsuite/ChangeLog:

        * gcc.dg/vect/costmodel/riscv/rvv/pr114264.c: New test.

Signed-off-by: demin.han <demin....@starfivetech.com>
---
 gcc/config/riscv/riscv-vector-costs.cc            |  2 ++
 .../gcc.dg/vect/costmodel/riscv/rvv/pr114264.c    | 15 +++++++++++++++
 2 files changed, 17 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/pr114264.c

diff --git a/gcc/config/riscv/riscv-vector-costs.cc 
b/gcc/config/riscv/riscv-vector-costs.cc
index 7c9840df4e9..f13a1296b31 100644
--- a/gcc/config/riscv/riscv-vector-costs.cc
+++ b/gcc/config/riscv/riscv-vector-costs.cc
@@ -413,6 +413,8 @@ compute_local_live_ranges (
                                  auto *r = get_live_range (live_ranges, arg);
                                  gcc_assert (r);
                                  (*r).second = MAX (point, (*r).second);
+                                 biggest_mode = get_biggest_mode (
+                                   biggest_mode, TYPE_MODE (TREE_TYPE (arg)));
                                }
                            }
                          else
diff --git a/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/pr114264.c 
b/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/pr114264.c
new file mode 100644
index 00000000000..7853f292af7
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/pr114264.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64gcv -mabi=lp64d -O3 -ftree-vectorize 
--param=riscv-autovec-lmul=dynamic" } */
+
+char *jpeg_difference7_input_buf;
+void
+jpeg_difference7 (int *diff_buf)
+{
+  unsigned width;
+  int samp, Rb;
+  while (--width)
+    {
+      Rb = samp = *jpeg_difference7_input_buf;
+      *diff_buf++ = -(int) (samp + (long) Rb >> 1);
+    }
+}
-- 
2.44.0