[PATCH] D94645: [AMDGPU] Fix llvm.amdgcn.init.exec and frame materialization

[Ruiling, Song via Phabricator via llvm-commits]

ruiling added inline comments.


================
Comment at: llvm/lib/Target/AMDGPU/SILowerControlFlow.cpp:689-714
+  MachineInstr *FirstMI = &*MBB->begin();
+  Register InputReg = MI.getOperand(0).getReg();
+  bool IsEntryBlock = &*MF.begin() == MBB;
+
+  if (IsEntryBlock) {
+    // Move COPY to beginning of block.
+    bool Found = false;
----------------
critson wrote:
> ruiling wrote:
> > I think this piece of code can be simplified something like below:
> > 
> > ```
> >         Register InputReg = MI.getOperand(0).getReg();
> >         MachineInstr *FirstMI = &*MBB->begin();
> >         if (InputReg.isVirtual()) {
> >           MachineInstr *DefInstr = MRI->getVRegDef(InputReg);
> >           assert(DefInstr && DefInstr->isCopy());
> >           if (DefInstr->getParent() == MBB && DefInstr != FirstMI) {
> >             // If the `InputReg` is defined in current block, we also need to
> >             // move that instruction to the beginning of the block.
> >             DefInstr->removeFromParent();
> >             MBB->insert(FirstMI, DefInstr);
> >             if (LIS)
> >               LIS->handleMove(*DefInstr);
> >           }
> >         }
> > 
> > ```
> Sure.  Although I had to update the code to handle the case the definition is the first instruction.
Yes, that need to be fixed. I have not tested the code.


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https://reviews.llvm.org/D94645