SILOptimzer: add a workaround to repair the Windows builds

The current implementation of `InstModCallbacks` seems to fail to invoke
the `eraseFromParent` on the instruction when performing GlobalOpt.  As
a result, we end up with undefined references that are preserved.  This
workaround ensures that the instruction is removed.  This should allow
us to finally refresh the Windows toolchain.

Author: compnerd

lib/SILOptimizer/IPO/GlobalOpt.cpp

@@ -399,8 +399,12 @@ replaceLoadsByKnownValue(SILFunction *InitF, SILGlobalVariable *SILG,
     replaceLoadsFromGlobal(initCall, initVal, cloner);
 
     // Remove all instructions which are dead now.
-    InstructionDeleter deleter;
+    InstructionDeleter deleter(
+        InstModCallbacks()
+            .onDelete([](SILInstruction *I) { I->eraseFromParent(); })
+    );
     deleter.recursivelyDeleteUsersIfDead(initCall);
+
     if (initCall->use_empty()) {
       // The call to the addressor is dead as well and can be removed.
       auto *callee = dyn_cast<FunctionRefInst>(initCall->getCallee());

lib/SILOptimizer/Transforms/CSE.cpp

@@ -725,7 +725,10 @@ bool CSE::processLazyPropertyGetters() {
     SILBasicBlock *callBlock = ai->getParent();
 
     // Inline the getter...
-    InstructionDeleter deleter;
+    InstructionDeleter deleter(
+        InstModCallbacks()
+            .onDelete([](SILInstruction *I) { I->eraseFromParent(); })
+    );
     SILInliner::inlineFullApply(ai, SILInliner::InlineKind::PerformanceInline,
                                 FuncBuilder, deleter);
     deleter.cleanupDeadInstructions();