[llvm] [AMDGPU] Mitigate GFX12 VALU read SGPR hazard (PR #100067)

[Carl Ritson via llvm-commits]

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@@ -2759,6 +2762,36 @@ bool GCNHazardRecognizer::ShouldPreferAnother(SUnit *SU) {
   return false;
 }
 
+// Adjust global offsets for instructions bundled with S_GETPC_B64 after
+// insertion of a new instruction.
+static void updateGetPCBundle(MachineInstr *NewMI) {
+  if (!NewMI->isBundled())
+    return;
+
+  // Find start of bundle.
+  auto I = NewMI->getIterator();
+  while (I->isBundledWithPred())
+    I--;
+  if (I->isBundle())
+    I++;
+
+  // Bail if this is not an S_GETPC bundle.
+  if (I->getOpcode() != AMDGPU::S_GETPC_B64)
+    return;
+
+  // Update offsets of any references in the bundle.
+  const unsigned NewBytes = NewMI->getDesc().getSize();
+  auto NextMI = std::next(NewMI->getIterator());
+  auto End = NewMI->getParent()->end();
+  while (NextMI != End && NextMI->isBundledWithPred()) {
+    for (auto &Operand : NextMI->operands()) {
+      if (Operand.isGlobal())
+        Operand.setOffset(Operand.getOffset() + NewBytes);
+    }
+    NextMI++;
+  }
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perlfu wrote:

Done

https://github.com/llvm/llvm-project/pull/100067