On Fri, 14 Feb 2025 05:04:20 PST (-0800), ji...@linux.alibaba.com wrote:
> According to the definition in gcc/config/riscv/t-linux, after obtaining
> the reused multilib_dir result using TARGET_COMPUTE_MULTILIB, we should
> set multilib_os_dir to its parent directory.
>
> For example, when building GCC with the options "--enable-multilib
> --with-arch=rv64gc --with-abi=lp64d" and using GCC to compile RV32GC
> programs, the current multilib_dir is set to "lib32/ilp32d", and
> multilib_os_dir is also "lib32/ilp32d". This results in an inability to
> locate the path "lib/lib32/ilp32d" during the linking process(as it does
> not exist); the actual path should be "lib/../lib32/ilp32d".
>
> Library Search Order Before Applying This Patch (Incorrect):
>
> 1. lib/gcc/riscv64-unknown-linux-gnu/15.0.1/lib32/ilp32d/
> 2. lib/gcc/riscv64-unknown-linux-gnu/15.0.1/
> 3.
> lib/gcc/riscv64-unknown-linux-gnu/15.0.1/../../../../riscv64-unknown-linux-gnu/lib/
> 4. sysroot/lib32/ilp32d/
> 5. sysroot/usr/lib32/ilp32d/
> 6. sysroot/lib/
>
> Library Search Order After Applying This Patch:
>
> 1. lib/gcc/riscv64-unknown-linux-gnu/15.0.1/lib32/ilp32d/
> 2.
> lib/gcc/riscv64-unknown-linux-gnu/15.0.1/../../../../riscv64-unknown-linux-gnu/lib/../lib32/ilp32d/
> 3. sysroot/lib/../lib32/ilp32d/
> 4. lib/gcc/riscv64-unknown-linux-gnu/15.0.1/
> 5.
> lib/gcc/riscv64-unknown-linux-gnu/15.0.1/../../../../riscv64-unknown-linux-gnu/lib/
> 6. sysroot/lib32/ilp32d/
> 7. sysroot/usr/lib32/ilp32d/
> 8. sysroot/lib/
>
> Clearly, two valid paths (2 and 3) have been added, which is the correct
> behavior.
We were talking about this in the patchwork meeting this morning, and
nobody could figure out why these paths are the desired behavior here.
Unless I'm reading something wrong, this just adds two new paths:
lib/gcc/riscv64-unknown-linux-gnu/15.0.1/../../../../riscv64-unknown-linux-gnu/lib/../lib32/ilp32d/
sysroot/lib/../lib32/ilp32d/
For the first one, if I remove all the ".." that resolves to
"riscv64-unknown-linux-gnu/lib32/ilp32d/". That looks odd to me, as I'd
expect that to be a sysroot-based path.
For the second one, I get "sysroot/lib32/ilp32d/", which is already in
the list.
So I'm not quite sure what's going on here.
> gcc/ChangeLog:
>
> * common/config/riscv/riscv-common.cc (riscv_compute_multilib_os):
> Implement TARGET_COMPUTE_MULTILIB_OS
> (TARGET_COMPUTE_MULTILIB_OS): Defined.
> * config/riscv/linux.h (RISCV_USE_CUSTOMISED_MULTI_LIB_OS): New.
> ---
> gcc/common/config/riscv/riscv-common.cc | 32 +++++++++++++++++++++++++
> gcc/config/riscv/linux.h | 1 +
> 2 files changed, 33 insertions(+)
>
> diff --git a/gcc/common/config/riscv/riscv-common.cc
> b/gcc/common/config/riscv/riscv-common.cc
> index 5038f0eb959..526d1fb9ca2 100644
> --- a/gcc/common/config/riscv/riscv-common.cc
> +++ b/gcc/common/config/riscv/riscv-common.cc
> @@ -2426,9 +2426,41 @@ riscv_compute_multilib (
> }
> }
>
> +#ifndef RISCV_USE_CUSTOMISED_MULTI_LIB_OS
> +#define RISCV_USE_CUSTOMISED_MULTI_LIB_OS 0
> +#endif
> +
> +/* Implement TARGET_COMPUTE_MULTILIB_OS. */
> +static const char *
> +riscv_compute_multilib_os (
> + const char *multilib_os_dir,
> + const char *multilib_dir)
> +{
> + if (!RISCV_USE_CUSTOMISED_MULTI_LIB_OS)
> + return multilib_os_dir;
> +
> + /* We don't need to do anything if we don't get multilib_dir. */
> + if (multilib_dir == NULL)
> + return multilib_os_dir;
> +
> + /* If multilib_dir is the default, multilib_os_dir should also be the
> + default. */
> + if (strcmp (multilib_dir, ".") == 0 || multilib_os_dir != NULL)
> + return multilib_os_dir;
> +
> + /* According to the definition in gcc/config/riscv/t-linux, We need to use
> the
> + multilib_dir's upper level directory instead of a simple copy. In order
> + to maintain the original logic, we need to use the multilib_dir upper
> + level directory. */
> + return concat ("../", multilib_dir , NULL);
> +}
> +
> #undef TARGET_COMPUTE_MULTILIB
> #define TARGET_COMPUTE_MULTILIB riscv_compute_multilib
>
> +#undef TARGET_COMPUTE_MULTILIB_OS
> +#define TARGET_COMPUTE_MULTILIB_OS riscv_compute_multilib_os
> +
> vec<const char *>
> riscv_get_valid_option_values (int option_code,
> const char *prefix ATTRIBUTE_UNUSED)
> diff --git a/gcc/config/riscv/linux.h b/gcc/config/riscv/linux.h
> index 9060c940a44..4ac7477bdf4 100644
> --- a/gcc/config/riscv/linux.h
> +++ b/gcc/config/riscv/linux.h
> @@ -68,3 +68,4 @@ along with GCC; see the file COPYING3. If not see
> "/usr/lib/ "
>
> #define RISCV_USE_CUSTOMISED_MULTI_LIB select_by_abi
> +#define RISCV_USE_CUSTOMISED_MULTI_LIB_OS 1
