[Mesa-dev] [PATCH] configure.ac: Rework LLVM dependency handling

[Emil Velikov]

Hi Tobias,

On 8 October 2016 at 16:55, Tobias Droste <tdroste at gmx.de> wrote:
> After this change each driver can request LLVM with a specific version
> and specific targets/components anywhere.
>
> For gallium "--enable-gallium-llvm" is only needed if at least one
> driver calls "gallium_require_llvm()".
> If the flag is set to auto it will default to no now if no driver with
> "gallium_require_llvm()" is included.
>
> If gallium swrast driver is selected and LLVM is installed and
> "--enable-gallium-llvm" is yes or auto, it defaults to llvmpipe,
> otherwise to softpipe.
>
> Signed-off-by: Tobias Droste <tdroste at gmx.de>
> ---
>  configure.ac | 451 +++++++++++++++++++++++++++++++++--------------------------
>  1 file changed, 249 insertions(+), 202 deletions(-)
>
Huge thanks for starting to unwravel this.

Since the configure code is quite picky, please split out the code
movement from the functionality changes.


> +llvm_add_component() {
> +    new_llvm_component=$1
> +    fail_if_not_present=$2
> +    driver_name=$3
> +
> +    if test -z "$LLVM_COMPONENTS"; then
> +        # Make the string non zero length
> +        LLVM_COMPONENTS=" "
> +
I'm not sure that this will work. For example
$unset FOO && export FOO=" " && test -z $FOO && echo A
A

> +        # Required default components
> +        llvm_add_component "engine" "yes" $driver_name
> +        llvm_add_component "bitwriter" "yes" $driver_name
> +        llvm_add_component "mcjit" "yes" $driver_name
> +        llvm_add_component "mcdisassembler" "yes" $driver_name
> +
At the same time I'm not sure that calling a function recursively will
end up well, in the long run.

That said using add_compulsory (mandatory/other) and add_optional
helpers would be better than the current "yes" "no", wouldn't it ?

Thanks
Emil