[RISC-V] attribute target arch=+zvfh doesn't add builtins

[antonblanchard]

This fails when building with -march=rv64gc:

#include <riscv_vector.h>

__attribute__((target("arch=+v,+zvfh")))
void testcase(_Float16 *src, _Float16 *dst, int len)
{
        size_t nr = __riscv_vsetvl_e16m2(len);
        vfloat16m2_t a = __riscv_vle16_v_f16m2(src, nr);
        __riscv_vse16_v_f16m2(dst, a, nr);
}

with:

testcase.c:7:19: error: call to undeclared function '__riscv_vle16_v_f16m2'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]

It works with -march=rv64gcv_zvfh

[llvmbot]

@llvm/issue-subscribers-backend-risc-v

Author: Anton Blanchard (antonblanchard)

This fails when building with `-march=rv64gc`:

#include <riscv_vector.h>

__attribute__((target("arch=+v,+zvfh")))
void testcase(_Float16 *src, _Float16 *dst, int len)
{
        size_t nr = __riscv_vsetvl_e16m2(len);
        vfloat16m2_t a = __riscv_vle16_v_f16m2(src, nr);
        __riscv_vse16_v_f16m2(dst, a, nr);
}

with:

testcase.c:7:19: error: call to undeclared function '__riscv_vle16_v_f16m2'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]

It works with -march=rv64gcv_zvfh

[llvmbot]

@llvm/issue-subscribers-clang-driver

Author: Anton Blanchard (antonblanchard)

This fails when building with `-march=rv64gc`:

#include <riscv_vector.h>

__attribute__((target("arch=+v,+zvfh")))
void testcase(_Float16 *src, _Float16 *dst, int len)
{
        size_t nr = __riscv_vsetvl_e16m2(len);
        vfloat16m2_t a = __riscv_vle16_v_f16m2(src, nr);
        __riscv_vse16_v_f16m2(dst, a, nr);
}

with:

testcase.c:7:19: error: call to undeclared function '__riscv_vle16_v_f16m2'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]

It works with -march=rv64gcv_zvfh

[topperc]

@4vtomat can you take a look?

[tclin914]

Fixed by : #115436