[PATCH] D141014: [Support][SelectionDAG][GlobalISel] Hoist PostShift adjustment for IsADd into UnsignedDivideUsingMagic.

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added inline comments.


================
Comment at: llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp:4965-4966
 
-      if (!magics.IsAdd) {
-        assert(magics.ShiftAmount < Divisor.getBitWidth() &&
-               "We shouldn't generate an undefined shift!");
-        PostShift = magics.ShiftAmount;
-        PreShift = magics.PreShift;
-      } else {
-        assert(magics.PreShift == 0 && "Unexpected pre-shift");
-        PostShift = magics.ShiftAmount - 1;
-        SelNPQ = true;
-      }
+      assert(magics.ShiftAmount < Divisor.getBitWidth() &&
+             "We shouldn't generate an undefined shift!");
+      assert((!magics.IsAdd || magics.PreShift == 0) && "Unexpected pre-shift");
----------------
Probably want similar assertion for `PreShift`?


================
Comment at: llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp:6059-6060
 
-      if (!magics.IsAdd) {
-        assert(magics.ShiftAmount < Divisor.getBitWidth() &&
-               "We shouldn't generate an undefined shift!");
-        PostShift = magics.ShiftAmount;
-        PreShift = magics.PreShift;
-      } else {
-        assert(magics.PreShift == 0 && "Unexpected pre-shift");
-        PostShift = magics.ShiftAmount - 1;
-        SelNPQ = true;
-      }
+      assert(magics.ShiftAmount < Divisor.getBitWidth() &&
+             "We shouldn't generate an undefined shift!");
+      assert((!magics.IsAdd || magics.PreShift == 0) &&
----------------
Probably want similar assertion for `PreShift`?


================
Comment at: llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp:6063
+             "Unexpected pre-shift");
+      PostShift = magics.ShiftAmount;
+      PreShift = magics.PreShift;
----------------
The name `PostShift` be propagated into `UnsignedDivisionByConstantInfo` struct?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D141014/new/

https://reviews.llvm.org/D141014