Add a flag to turn off analysis of function calls in AllocBoxToStack

Author: meg-gupta

lib/SILOptimizer/Transforms/AllocBoxToStack.cpp

@@ -44,6 +44,10 @@ static llvm::cl::opt<unsigned> MaxLocalApplyRecurDepth(
     "max-local-apply-recur-depth", llvm::cl::init(4),
     llvm::cl::desc("Max recursive depth for analyzing local functions"));
 
+static llvm::cl::opt<bool> AllocBoxToStackAnalyzeApply(
+    "allocbox-to-stack-analyze-apply", llvm::cl::init(true),
+    llvm::cl::desc("Analyze functions into while alloc_box is passed"));
+
 //===-----------------------------------------------------------------------===//
 //                 SIL Utilities for alloc_box Promotion
 //===----------------------------------------------------------------------===//
@@ -320,6 +324,10 @@ static bool checkLocalApplyBody(Operand *O,
 // AllocBoxToStack opt. We don't want to increase code size, so this is
 // restricted only for private local functions currently.
 static bool isOptimizableApplySite(ApplySite Apply) {
+  if (!AllocBoxToStackAnalyzeApply) {
+    // turned off explicitly
+    return false;
+  }
   auto callee = Apply.getReferencedFunctionOrNull();
   if (!callee) {
     return false;

test/SILOptimizer/allocboxtostack_localapply_ossa.sil

@@ -414,10 +414,10 @@ bb0(%0 : @guaranteed ${ var Int64 }):
 // Order of function calls constructed in PromotedOperands: bar innercommon local1 bas innercommon local2
 // AppliesToSpecialize should have the order: bar bas innercommon local1 local2
 // Since we don't maintain any tree like data structure with more info on the call tree, this is not possible to contruct today 
-// CHECK-LABEL: sil [noinline] @$s26allocboxtostack_localapply8testdfs2SiyF :
+// CHECK-LABEL: sil [noinline] [ossa] @$testdfs2 :
 // CHECK: alloc_box ${ var Int }, var, name "x"
 // CHECK: alloc_box ${ var Int }, var, name "y"
-// CHECK-LABEL:} // end sil function '$s26allocboxtostack_localapply8testdfs2SiyF'
+// CHECK-LABEL:} // end sil function '$testdfs2'
 sil [noinline] [ossa] @$testdfs2 : $@convention(thin) () -> Int {
 bb0:
   %0 = alloc_box ${ var Int }, var, name "x"