[PATCH] D86578: [TargetLowering] Combine known bits for icmp in SimplifySetCC (PR41182)

[Craig Topper via Phabricator via llvm-commits]

craig.topper added inline comments.


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Comment at: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:14059
+      // unconditionally take the branch, remove all other successors of CurBB
+      auto SuccMBB = CurMBB->succ_begin();
+      while (SuccMBB != CurMBB->succ_end()) {
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darcangelo.matthew wrote:
> craig.topper wrote:
> > I'm not sure if we can really do this from SelectionDAG. Is there anywhere else that does this in tree?
> > I'm not sure if we can really do this from SelectionDAG. Is there anywhere else that does this in tree?
> 
> I found the UnreachableMachineBlockElim pass which may be able to be enhanced for this, but I'm still looking
Sorry, I meant is there anywhere else that does something like this while SelectionDAG exists?


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Comment at: llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp:3998
           C1 == APInt::getSignedMinValue(OperandBitSize)) {
-        SDValue ConstMinusOne =
-            DAG.getConstant(APInt::getAllOnesValue(OperandBitSize), dl,
-                            N1.getValueType());
+        SDValue ConstMinusOne = DAG.getConstant(
+            APInt::getAllOnesValue(OperandBitSize), dl, N1.getValueType());
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Is this just a formatting change?


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Comment at: llvm/test/CodeGen/X86/test-shrink.ll:574
   ret void
 no:
   ret void
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darcangelo.matthew wrote:
> craig.topper wrote:
> > Can we pre-commit the IR changes here?
> Thank you for taking a look at the changes. 
> 
> > Can we pre-commit the IR changes here?
> 
> Sorry, would you be able to elaborate what you mean here? Do you mean separate these out into another pre-commit review?
I went ahead and modified the tests in trunk. Can you rebase this patch?


Repository:
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  https://reviews.llvm.org/D86578/new/

https://reviews.llvm.org/D86578