Merge pull request #21 from kito-cheng/v-ext-marco

Add misc macro for vector extensions.

Author: kito-cheng

riscv-c-api.md

@@ -40,6 +40,60 @@ https://creativecommons.org/licenses/by/4.0/.
 | __riscv_flen        | <ul><li>32 if the F extension is available **or**</li><li>64 if `D` extension available **or**</li><li>128 if `Q` extension available</li></ul> | `F` extension is available. |
 | __riscv_32e         | 1     | `E` extension is available.   |
 | __riscv_vector      | 1     | Implies that any of the vector extensions (`v` or `zve*`) is available |
+| __riscv_v_min_vlen    | <N> (see [__riscv_v_min_vlen](#__riscv_v_min_vlen)) | The `V` extension or one of the `Zve*` extensions is available. |
+| __riscv_v_elen     | <N> (see [__riscv_v_elen](#__riscv_v_elen)) | The `V` extension or one of the `Zve*` extensions is available. |
+| __riscv_v_elen_fp  | <N> (see [__riscv_v_elen_fp](#__riscv_v_elen_fp)) | The `V` extension or one of the `Zve*` extensions is available. |
+
+### __riscv_v_min_vlen
+
+The `__riscv_v_min_vlen` macro expands to the minimal VLEN, in bits, mandated
+by the available vector extension, if any.
+
+The value of `__riscv_v_min_vlen` is defined by the following rules:
+- 128, if the `V` extension is present;
+- 32, if one of the `Zve32{x,f}` extensions is present;
+- 64, if one of the `Zve64{x,f,d}` extensions is present;
+- `N`, if one of the `Zvl<N>b` extensions, `N` in `{32,64,128,256,512,1024}`,
+is present.
+
+If multiple rules apply, the maximum value is taken.
+If none of the rules apply, `__riscv_v_min_vlen` is undefined.
+
+Examples:
+
+- `__riscv_v_min_vlen` is 128 for `rv64gcv`
+- `__riscv_v_min_vlen` is 512 for `rv32gcv_zvl512b`
+- `__riscv_v_min_vlen` is 256 for `rv32gcv_zvl32b_zvl256b`
+- `__riscv_v_min_vlen` is 128 for `rv64gcv_zvl32b`
+
+### __riscv_v_elen
+
+The `__riscv_v_elen` macro expands to the supported element length, in bits,
+of any non-floating-point vector operand of any vector instruction in the
+available vector extension, if any. (Stricter upper bounds may apply to
+particular operands of particular instructions.)
+
+
+The value of `__riscv_v_elen` is defined by the following rules:
+- 64, if the `V` extension or one of the `Zve64{x,f,d}` extensions is present; and
+- 32, if one of the `Zve32{x,f}` extensions is present.
+If multiple rules apply, the maximum value is taken.
+If none of the rules apply, `__riscv_v_elen` is undefined.
+
+### __riscv_v_elen_fp
+
+The `__riscv_v_elen_fp` macro expands to the supported element length, in bits,
+of any floating-point vector operand of any vector instruction in the available
+vector extension, if any. (Stricter upper bounds may apply to particular
+operands of particular instructions.)
+
+The value of `__riscv_v_elen_fp` is defined by the following rules:
+- 64, if one of the `V` or `Zve64d` extensions is present;
+- 32, if one of the `Zve{32,64}f` extensions is present; and
+- 0, if one of the `Zve{32,64}x` extensions is present.
+If multiple rules apply, the maximum value is taken.
+If none of the rules apply, `__riscv_v_elen_fp` is undefined.
+
 
 ### Architecture Extension Test Macro