[PATCH v1] RISC-V: Make full-vec-move1.c test robust for optimization

[pan2 . li]

From: Pan Li <pan2...@intel.com>

During investigate the support of early break autovec, we notice
the test full-vec-move1.c will be optimized to 'return 0;' in main
function body.  Because somehow the value of V type is compiler
time constant,  and then the second loop will be considered as
assert (true).

Thus,  the ccp4 pass will eliminate these stmt and just return 0.

typedef int16_t V __attribute__((vector_size (128)));

int main ()
{
  V v;
  for (int i = 0; i < sizeof (v) / sizeof (v[0]); i++)
    (v)[i] = i;

  V res = v;
  for (int i = 0; i < sizeof (v) / sizeof (v[0]); i++)
    assert (res[i] == i); // will be optimized to assert (true)
}

This patch would like to introduce a extern function to use the res[i]
that get rid of the ccp4 optimization.

gcc/testsuite/ChangeLog:

        * gcc.target/riscv/rvv/autovec/vls-vlmax/full-vec-move1.c:
        Introduce extern func use to get rid of ccp4 optimization.

Signed-off-by: Pan Li <pan2...@intel.com>
---
 .../gcc.target/riscv/rvv/autovec/vls-vlmax/full-vec-move1.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git 
a/gcc/testsuite/gcc.target/riscv/rvv/autovec/vls-vlmax/full-vec-move1.c 
b/gcc/testsuite/gcc.target/riscv/rvv/autovec/vls-vlmax/full-vec-move1.c
index d73bad4af6f..fae2ae91572 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/autovec/vls-vlmax/full-vec-move1.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/vls-vlmax/full-vec-move1.c
@@ -2,11 +2,12 @@
 /* { dg-additional-options "-std=c99 -O3 -march=rv64gcv_zvl128b -mabi=lp64d 
-fno-vect-cost-model -mrvv-vector-bits=zvl" } */
 
 #include <stdint-gcc.h>
-#include <assert.h>
 
 /* This would cause us to emit a vl1r.v for VNx4HImode even when
    the hardware vector size vl > 64.  */
 
+extern int16_t test_element (int16_t);
+
 typedef int16_t V __attribute__((vector_size (128)));
 
 int main ()
@@ -14,9 +15,10 @@ int main ()
   V v;
   for (int i = 0; i < sizeof (v) / sizeof (v[0]); i++)
     (v)[i] = i;
+
   V res = v;
   for (int i = 0; i < sizeof (v) / sizeof (v[0]); i++)
-    assert (res[i] == i);
+    test_element (res[i]);
 }
 
 /* { dg-final { scan-assembler-not {vl[1248]r.v} } }  */
-- 
2.34.1