Merge pull request #62453 from nate-chandler/opaque-values/2/20221207

[AddressLowering] Omit dealloc_stack in dead ends.

Author: nate-chandler

lib/SILOptimizer/Mandatory/AddressLowering.cpp

@@ -149,6 +149,7 @@
 #include "swift/SIL/SILInstruction.h"
 #include "swift/SIL/SILValue.h"
 #include "swift/SIL/SILVisitor.h"
+#include "swift/SILOptimizer/Analysis/DeadEndBlocksAnalysis.h"
 #include "swift/SILOptimizer/Analysis/PostOrderAnalysis.h"
 #include "swift/SILOptimizer/PassManager/Transforms.h"
 #include "swift/SILOptimizer/Utils/BasicBlockOptUtils.h"
@@ -413,6 +414,9 @@ struct AddressLoweringState {
   // Dominators remain valid throughout this pass.
   DominanceInfo *domInfo;
 
+  // Dead-end blocks remain valid through this pass.
+  DeadEndBlocks *deBlocks;
+
   InstructionDeleter deleter;
 
   // All opaque values mapped to their associated storage.
@@ -441,9 +445,10 @@ struct AddressLoweringState {
   // Handle moves from a phi's operand storage to the phi storage.
   std::unique_ptr<PhiRewriter> phiRewriter;
 
-  AddressLoweringState(SILFunction *function, DominanceInfo *domInfo)
+  AddressLoweringState(SILFunction *function, DominanceInfo *domInfo,
+                       DeadEndBlocks *deBlocks)
       : function(function), loweredFnConv(getLoweredFnConv(function)),
-        domInfo(domInfo) {
+        domInfo(domInfo), deBlocks(deBlocks) {
     for (auto &block : *function) {
       if (block.getTerminator()->isFunctionExiting())
         exitingInsts.push_back(block.getTerminator());
@@ -1332,6 +1337,8 @@ void OpaqueStorageAllocation::finalizeOpaqueStorage() {
     // a use projection.
     computeDominatedBoundaryBlocks(alloc->getParent(), pass.domInfo, boundary);
     for (SILBasicBlock *deallocBlock : boundary) {
+      if (pass.deBlocks->isDeadEnd(deallocBlock))
+        continue;
       auto deallocBuilder = pass.getBuilder(deallocBlock->back().getIterator());
       deallocBuilder.createDeallocStack(pass.genLoc(), alloc);
     }
@@ -3859,8 +3866,10 @@ void AddressLowering::runOnFunction(SILFunction *function) {
   removeUnreachableBlocks(*function);
 
   auto *dominance = PM->getAnalysis<DominanceAnalysis>();
+  auto *deadEnds = PM->getAnalysis<DeadEndBlocksAnalysis>();
 
-  AddressLoweringState pass(function, dominance->get(function));
+  AddressLoweringState pass(function, dominance->get(function),
+                            deadEnds->get(function));
 
   // ## Step #1: Map opaque values
   //

test/SILOptimizer/address_lowering.sil

@@ -1740,6 +1740,19 @@ bb2:
   unwind
 }
 
+// CHECK-LABEL: sil [ossa] @testUnreachable1NoDestroy : {{.*}} {
+// CHECK:         [[STORAGE:%[^,]+]] = alloc_stack $T                             
+// CHECK:         apply undef<T>([[STORAGE]])
+// CHECK:         apply undef<T>([[STORAGE]])
+// CHECK:         unreachable                                     
+// CHECK-LABEL: } // end sil function 'testUnreachable1NoDestroy'
+sil [ossa] @testUnreachable1NoDestroy : $@convention(thin) <T> () -> () {
+bb0:
+    %instance = apply undef<T>() : $@convention(thin) <τ> () -> @out τ
+    apply undef<T>(%instance) : $@convention(thin) <τ> (@in_guaranteed τ) -> ()
+    unreachable
+}
+
 sil [ossa] @use_T : $@convention(thin) <T> (@in T) -> ()
 
 // CHECK-LABEL: sil [ossa] @test_checked_cast_br1 : $@convention(method) <T> (@in Any) -> () {