[llvm] [AMDGPU] Relax VOPD constraints for gfx12+ with data deps (PR #191264)

[Matt Arsenault via llvm-commits]

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@@ -34,9 +34,38 @@ using namespace llvm;
 
 #define DEBUG_TYPE "gcn-vopd-utils"
 
+static bool isMulticycleOp(const MachineInstr &MI) {
+  unsigned Opc = MI.getOpcode();
+  return AMDGPU::isDPMACCInstruction(Opc);
+}
+
+bool llvm::dataDependency(const MachineInstr &FirstMI,
+                          const MachineInstr &SecondMI) {
+  const GCNSubtarget &ST = FirstMI.getMF()->getSubtarget<GCNSubtarget>();
+  const SIRegisterInfo *TRI = dyn_cast<SIRegisterInfo>(ST.getRegisterInfo());
+  for (const auto &Use : SecondMI.all_uses()) {
+    if (Use.isReg() && FirstMI.modifiesRegister(Use.getReg(), TRI))
+      return true;
+  }
+  return false;
+}
+
+// If SecondMI writes a source of FirstMI, we can
+// still form VOPD as SecondMI::FirstMI in cases where VOPD reads all sources
+// before writing any destination.
+bool llvm::isAntidependencyAllowed(const MachineInstr &OpX) {
+  const GCNSubtarget &ST = OpX.getMF()->getSubtarget<GCNSubtarget>();
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arsenm wrote:

This kind of thing belongs in SIInstrInfo?

https://github.com/llvm/llvm-project/pull/191264