[llvm] [AMDGPU][True16][CodeGen] update waitcnt for true16 (PR #128927)

[Jay Foad via llvm-commits]

================
@@ -748,27 +748,32 @@ RegInterval WaitcntBrackets::getRegInterval(const MachineInstr *MI,
 
   RegInterval Result;
 
-  unsigned Reg = TRI->getEncodingValue(AMDGPU::getMCReg(Op.getReg(), *ST)) &
-                 AMDGPU::HWEncoding::REG_IDX_MASK;
+  MCRegister MCReg = AMDGPU::getMCReg(Op.getReg(), *ST);
+  unsigned RegIdx = TRI->getHWRegIndex(MCReg);
+  assert(isUInt<8>(RegIdx));
 
+  const TargetRegisterClass *RC = TRI->getPhysRegBaseClass(Op.getReg());
+  unsigned Size = TRI->getRegSizeInBits(*RC);
+
+  // AGPRs/VGPRs are tracked every 16 bits, SGPRs by 32 bits
   if (TRI->isVectorRegister(*MRI, Op.getReg())) {
-    assert(Reg <= SQ_MAX_PGM_VGPRS);
+    unsigned Reg = (RegIdx << 1) | (AMDGPU::isHi16Reg(MCReg, *TRI) ? 1 : 0);
+    assert(Reg <= AGPR_OFFSET);
----------------
jayfoad wrote:

```suggestion
    unsigned Reg = RegIdx << 1 | (AMDGPU::isHi16Reg(MCReg, *TRI) ? 1 : 0);
    assert(Reg < AGPR_OFFSET);
```

https://github.com/llvm/llvm-project/pull/128927