[llvm] [LoongArch] Add patterns for vstelm instructions (PR #139201)

[via llvm-commits]

================
@@ -140,7 +140,48 @@ bool LoongArchRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
 
   bool FrameRegIsKill = false;
 
-  if (!isInt<12>(Offset.getFixed())) {
+  int FixedOffset = Offset.getFixed();
+  bool OffsetLegal = true;
+
+  // Handle offsets that exceed the immediate range of the instruction.
+  switch (MIOpc) {
+  case LoongArch::VSTELM_B:
+  case LoongArch::XVSTELM_B: {
+    OffsetLegal = isInt<8>(FixedOffset);
+    break;
+  }
----------------
heiher wrote:

We prefer to omit the inner braces to avoid unnecessary line noise.

https://github.com/llvm/llvm-project/pull/139201