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

[Michael Maitland via llvm-commits]

================
@@ -44,10 +45,50 @@ 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;
 
   getActionDefinitionsBuilder({G_ADD, G_SUB, G_AND, G_OR, G_XOR})
       .legalFor({s32, sXLen})
+      .legalFor(ST.hasVInstructions()
+                    ? std::initializer_list<LLT>{nxv2s8, nxv4s8, nxv8s8,
----------------
michaelmaitland wrote:

I think you can drop `std::initializer_list<LLT>` in this case. We only need it in the empty case because we cannot have {} on the right side of a :

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