Skip to content

Note Non-Interoperable Macros and Types #129

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 2 commits into
base: main
Choose a base branch
from
Open

Note Non-Interoperable Macros and Types #129

Changes from 1 commit
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
34ad833
Note Unstable Macros and Types
lenary Oct 15, 2025
57dc4cd
Address Feedback
lenary Oct 17, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
47 changes: 47 additions & 0 deletions src/c-api.adoc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -152,6 +152,31 @@ For example:
|`+__riscv_cmodel_large+` |1 |Defined if using `large` code model.
|===

[id=unstable_preprocessor_definitions]
=== Unstable Preprocessor Definitions

The following preprocessor definitions should be treated as unstable, and not
relied upon by the public interfaces in your code. They may be changed by new
compiler versions, compiler options, or on a per-processor basis.

.Unstable Preprocessor Definitions
[cols="30,~"]
|===
|*Name* |*Description*
|`+__GCC_CONSTRUCTIVE_SIZE+` |The maximum recommended size of contiguous memory occupied by two objects accessed with temporal locality by concurrent threads.
|`+__GCC_DESTRUCTIVE_SIZE+` |The minimum recommended offset between two concurrently-accessed objects to avoid additional performance degradation due to contention introduced by the implementation.
|`+INT_FASTN_WIDTH+` |Bit width of an object of type `+int_fastN_t+`
|`+INT_FASTN_MIN+` |Minimum value of an object of type `+int_fastN_t+`
|`+INT_FASTN_MAX+` |Maximum value of an object of type `+int_fastN_t+`
|`+INT_LEASTN_WIDTH+` |Bit width of an object of type `+int_leastN_t+`
|`+INT_LEASTN_MIN+` |Minimum value of an object of type `+int_leastN_t+`
|`+INT_LEASTN_MAX+` |Maximum value of an object of type `+int_leastN_t+`
|`+UINT_FASTN_WIDTH+` |Bit width of an object of type `+uint_fastN_t+`
|`+UINT_FASTN_MAX+` |Maximum value of an object of type `+uint_fastN_t+`
|`+UINT_LEASTN_WIDTH+` |Bit width of an object of type `+uint_leastN_t+`
|`+UINT_LEASTN_MAX+` |Maximum value of an object of type `+uint_leastN_t+`
|===

=== Deprecated Preprocessor Definitions

.fn-1: footnote:[Not all compilers provide `-mno-div` and `-mno-fdiv` option.]
Expand All @@ -170,6 +195,28 @@ For example:
|`+__riscv_compressed+` |1 |`C` extension is available. | `+__riscv_c+`
|===

== C Types

Most C type sizes and alignments are defined by the ABI.

=== Unstable C Type Sizes and Alignments

The following type sizes and alignments should be treated as unstable, and not
relied upon by the public interfaces in your code. They may be changed by new
compiler versions, compiler options, or on a per-processor basis.

.Unstable Type Sizes and Alignments
[cols="30,~"]
|===
|*Type* |*Description*
|`+int_fastN_t+` |Fastest signed integer types with widths of at least `+N+` bits.
|`+int_leastN_t+` |Smallest signed integer types with widths of at least `+N+` bits.
|`+uint_fastN_t+` |Fastest unsigned integer types with widths of at least `+N+` bits.
|`+uint_leastN_t+` |Smallest unsigned integer types with widths of at least `+N+` bits.
|===

The corresponding Macro constants are also unstable (see <<unstable_preprocessor_definitions, Unstable Preprocessor Definitions>>).

== Function Attributes

=== `+__attribute__((naked))+`
Expand Down
Loading