[llvm] [Matrix] Don't update Changed based on Visit* return value (NFC). (PR #142417)

[Jon Roelofs via llvm-commits]

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@@ -2105,29 +2108,27 @@ class LowerMatrixIntrinsics {
   }
 
   /// Lower load instructions, if shape information is available.
-  bool VisitLoad(LoadInst *Inst, Value *Ptr, IRBuilder<> &Builder) {
+  void VisitLoad(LoadInst *Inst, Value *Ptr, IRBuilder<> &Builder) {
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jroelofs wrote:

All of these visitors need to `auto I = ShapeMap.find(Inst);` and `assert` it was found, so maybe that ought to be hoisted into the caller and passed as an argument, WDYT?

https://github.com/llvm/llvm-project/pull/142417