[PATCH] D140569: [AVR] Custom lower 32-bit shift instructions

[Ben Shi via Phabricator via llvm-commits]

benshi001 added inline comments.


================
Comment at: llvm/lib/Target/AVR/AVRISelLowering.cpp:291
+      // 32-bit shifts are converted to a loop in IR.
+      llvm_unreachable("Expected a constant shift!");
+    }
----------------
`"Expected a constant shift amount!"`


================
Comment at: llvm/lib/Target/AVR/AVRISelLowering.cpp:1847
+    // Shift one to the left.
+    for (size_t i = 0; i < Regs.size(); i++) {
+      size_t Idx = Regs.size() - i - 1;
----------------
Would it be better to be 
```
for (ssize_t i = Regs.size() - 1; i >= 0; i--) {
 ...
 if (i == Regs.size() - 1) {
   ...
  } else {
   ...
  }
}
```


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D140569/new/

https://reviews.llvm.org/D140569