[PATCH] D87148: [ImplicitNullCheck] Handle Nonzero faulting pages and complex addressing

[Denis Antrushin via Phabricator via llvm-commits]

dantrushin added inline comments.


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Comment at: llvm/include/llvm/CodeGen/TargetInstrInfo.h:1287
+      std::pair<Register, bool> &BaseRegUsedInConstAddr,
+      std::pair<Register, bool> &IndexRegUsedInConstAddr,
+      const TargetRegisterInfo *TRI,
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These names are confusing. I've been scrolling back and forth for several minutes :)
Why not to pass and name them separately?


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Comment at: llvm/lib/CodeGen/ImplicitNullChecks.cpp:421
+      Scale != 0 && IndexRegUsedInConstAddr.first &&
+      IndexRegUsedInConstAddr.first != PointerReg;
 
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Do you really need to check that `BaseRegUsedInConstAddr.first` is not zero?
Would simple `BaseRegUsedInConstAddr.first != PointerReg` work here?

I also found positive names more readable, e.g. `bool BaseRegIsNullChecked = BaseRegUsedInConstAddr.first == PointerReg`

I think it is reasonable to assert `Scale !=0 || IndexRegUsedInConstAddr.first == 0` and remove Scale check.


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Comment at: llvm/lib/Target/X86/X86InstrInfo.cpp:3680
+
+  auto *BaseOp = &MemI.getOperand(MemRefBegin + X86::AddrBaseReg);
+  if (!BaseOp->isReg()) // Can be an MO_FrameIndex
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Any reason to use `auto *` instead of `auto &` ?
If I read it correctly, `BaseOp` is used to get base register only. Using reference you'd have less characters to type :)


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Comment at: llvm/lib/Target/X86/X86InstrInfo.cpp:3693
+  Scale = MemI.getOperand(MemRefBegin + X86::AddrScaleAmt).getImm();
+  auto *IndexOp = &MemI.getOperand(MemRefBegin + X86::AddrIndexReg);
+  auto IndexOpReg = IndexOp->getReg();
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ditto. `auto &IndexOp = MI.getOperand()` ?


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  https://reviews.llvm.org/D87148/new/

https://reviews.llvm.org/D87148