[llvm] [GlobalISel] Add a getTargetLowering method to IRTranslator. NFC (PR #83009)

[Matt Arsenault via llvm-commits]

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@@ -624,6 +624,10 @@ class IRTranslator : public MachineFunctionPass {
 
   StackProtectorDescriptor SPDescriptor;
 
+  const TargetLowering &getTargetLowering() {
+    return *MF->getSubtarget().getTargetLowering();
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arsenm wrote:

this can just be a simple member in IRTranslator, no need to query through the subtarget every time 

https://github.com/llvm/llvm-project/pull/83009