Set SIL stage to lowered at the *start* of address lowering

SIL is not in a consistent state during the lowering pass. We just make sure it is correct at the end of the pass. This broke PR #13283 (verifying convert_function instructions in the builder)

To workaround this issue we will be running the builder’s verifier when the SIL stage != SILStage::Lowered

The SIL stage is set to lowered at the end of the module pass. This means that if this is the first lowering pass said workaround would not work.

This commit sets the SIL stage to lowered at the beginning of the module pass instead

Author: Joe Shajrawi

lib/IRGen/LoadableByAddress.cpp

@@ -2499,11 +2499,14 @@ void LoadableByAddress::updateLoweredTypes(SILFunction *F) {
 
 /// The entry point to this function transformation.
 void LoadableByAddress::run() {
+  // Set the SIL state before the PassManager has a chance to run
+  // verification.
+  getModule()->setStage(SILStage::Lowered);
+
   for (auto &F : *getModule())
     runOnFunction(&F);
 
   if (modFuncs.empty()) {
-    getModule()->setStage(SILStage::Lowered);
     return;
   }
 
@@ -2643,10 +2646,6 @@ void LoadableByAddress::run() {
   // Fix all instructions that rely on block storage type
   fixStoreToBlockStorageInstrs();
 
-  // Set the SIL state before the PassManager has a chance to run
-  // verification.
-  getModule()->setStage(SILStage::Lowered);
-
   // Clean up the data structs:
   modFuncs.clear();
   conversionInstrs.clear();