[llvm] [clang] [clang-tools-extra] [llvm] Support IFuncs on Darwin platforms (PR #73686)

[Ahmed Bougacha via cfe-commits]

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@@ -144,7 +144,12 @@ bool CallLowering::lowerCall(MachineIRBuilder &MIRBuilder, const CallBase &CB,
   // Try looking through a bitcast from one function type to another.
   // Commonly happens with calls to objc_msgSend().
   const Value *CalleeV = CB.getCalledOperand()->stripPointerCasts();
-  if (const Function *F = dyn_cast<Function>(CalleeV))
+  if (const GlobalIFunc *IF = dyn_cast<GlobalIFunc>(CalleeV);
+      IF && MF.getTarget().getTargetTriple().isOSBinFormatMachO()) {
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ahmedbougacha wrote:

Heh, I did a double-take on the nesting; maybe embrace the dumber `isa<>`/`cast<>`? ;)

https://github.com/llvm/llvm-project/pull/73686