[llvm] [AMDGPU] Correctly insert s_nops for dst forwarding hazard (PR #100276)

[Matt Arsenault via llvm-commits]

================
@@ -913,26 +978,14 @@ int GCNHazardRecognizer::checkVALUHazards(MachineInstr *VALU) {
     const int Shift16DefWaitstates = 1;
 
     auto IsShift16BitDefFn = [this, VALU](const MachineInstr &MI) {
-      if (!SIInstrInfo::isVALU(MI))
-        return false;
-      const SIInstrInfo *TII = ST.getInstrInfo();
-      if (SIInstrInfo::isSDWA(MI)) {
-        if (auto *DstSel = TII->getNamedOperand(MI, AMDGPU::OpName::dst_sel))
-          if (DstSel->getImm() == AMDGPU::SDWA::DWORD)
-            return false;
-      } else {
-        if (!AMDGPU::hasNamedOperand(MI.getOpcode(), AMDGPU::OpName::op_sel) ||
-            !(TII->getNamedOperand(MI, AMDGPU::OpName::src0_modifiers)
-                  ->getImm() &
-              SISrcMods::DST_OP_SEL))
-          return false;
-      }
       const SIRegisterInfo *TRI = ST.getRegisterInfo();
-      if (auto *Dst = TII->getNamedOperand(MI, AMDGPU::OpName::vdst)) {
-        Register Def = Dst->getReg();
-
-        for (const MachineOperand &Use : VALU->explicit_uses()) {
-          if (Use.isReg() && TRI->regsOverlap(Def, Use.getReg()))
+      const MachineOperand *ForwardedDst = getDstSelForwardingOperand(MI, ST);
+      if (ForwardedDst) {
+        return consumesDstSelForwardingOperand(VALU, ForwardedDst, TRI);
+      } else if (MI.isInlineAsm()) {
----------------
arsenm wrote:

No else after return 
```suggestion
      }
      
      if (MI.isInlineAsm()) {
```

https://github.com/llvm/llvm-project/pull/100276