[llvm] [RISCV][GlobalISel] Legalize G_ADD, G_SUB, G_AND, G_OR, G_XOR on RISC-V Vector Extension (PR #71400)

[Craig Topper via llvm-commits]

================
@@ -31,15 +31,55 @@ RISCVLegalizerInfo::RISCVLegalizerInfo(const RISCVSubtarget &ST) {
   const LLT s32 = LLT::scalar(32);
   const LLT s64 = LLT::scalar(64);
 
+  const LLT nxv1s8 = LLT::scalable_vector(1, s8);
+  const LLT nxv2s8 = LLT::scalable_vector(2, s8);
+  const LLT nxv4s8 = LLT::scalable_vector(4, s8);
+  const LLT nxv8s8 = LLT::scalable_vector(8, s8);
+  const LLT nxv16s8 = LLT::scalable_vector(16, s8);
+  const LLT nxv32s8 = LLT::scalable_vector(32, s8);
+  const LLT nxv64s8 = LLT::scalable_vector(64, s8);
+
+  const LLT nxv1s16 = LLT::scalable_vector(1, s16);
+  const LLT nxv2s16 = LLT::scalable_vector(2, s16);
+  const LLT nxv4s16 = LLT::scalable_vector(4, s16);
+  const LLT nxv8s16 = LLT::scalable_vector(8, s16);
+  const LLT nxv16s16 = LLT::scalable_vector(16, s16);
+  const LLT nxv32s16 = LLT::scalable_vector(32, s16);
+
+  const LLT nxv1s32 = LLT::scalable_vector(1, s32);
+  const LLT nxv2s32 = LLT::scalable_vector(2, s32);
+  const LLT nxv4s32 = LLT::scalable_vector(4, s32);
+  const LLT nxv8s32 = LLT::scalable_vector(8, s32);
+  const LLT nxv16s32 = LLT::scalable_vector(16, s32);
+
+  const LLT nxv1s64 = LLT::scalable_vector(1, s64);
+  const LLT nxv2s64 = LLT::scalable_vector(2, s64);
+  const LLT nxv4s64 = LLT::scalable_vector(4, s64);
+  const LLT nxv8s64 = LLT::scalable_vector(8, s64);
+
   using namespace TargetOpcode;
 
+  const std::initializer_list<LLT> scalarLegalTypes = {s32, sXLen};
----------------
topperc wrote:

Ok maybe C++14 changed initializer_list behavior so that the underlying array lifetime gets extended.

```
The underlying array is a temporary array, in which each element is copy-initialized (except that narrowing conversions are invalid) from the corresponding element of the original initializer list. The lifetime of the underlying array is the same as any other [temporary object](https://www.enseignement.polytechnique.fr/informatique/INF478/docs/Cpp/en/cpp/language/lifetime.html%23Temporary_object_lifetime), except that initializing an initializer_list object from the array extends the lifetime of the array exactly like [binding a reference to a temporary](https://www.enseignement.polytechnique.fr/informatique/INF478/docs/Cpp/en/cpp/language/reference_initialization.html%23Lifetime_of_a_temporary) (with the same exceptions, such as for initializing a non-static class member). The underlying array may be allocated in read-only memory.
```

https://github.com/llvm/llvm-project/pull/71400