https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115654
Bug ID: 115654
Summary: __builtin_cpu_supports should accept specific CPU
names
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: alexhenrie24 at gmail dot com
Target Milestone: ---
I'd like to have a specific minimum supported CPU for some particular software,
but also allow the software to run on newer CPUs that support a superset of the
minimum CPU's features. For example, I could say that the compiled binary will
run on an AMD Zen 3 processor or any other compatible processor, including any
future Intel CPUs that support all of the Zen 3's features. If the software is
run on an unsupported CPU, it needs to print a user-friendly error message. I
can see two ways to do that:
1. Check for every possible CPU: __builtin_cpu_is("znver3") ||
__builtin_cpu_is("znver4") || __builtin_cpu_is("znver5"). This is tedious
because I'd have to add to the list whenever new CPUs are added to GCC and it's
easy to miss one.
2. Check for all of the required CPU features:
__builtin_cpu_supports("x86-64-v3") && __builtin_cpu_supports("pclmul") &&
__builtin_cpu_supports("vpclmulqdq"). This is tedious because I have to look up
all of the features that are enabled by -march=znver3 and it's easy to miss
one.
For my use case, it would be very helpful if I could just write
__builtin_cpu_supports("znver3") to know, regardless of whether the CPU really
_is_ a Zen 3, whether it is fully _compatible_ with a Zen 3.
