Add a SILOption to control whether we should use an aggressive form of

keeping large values indirect

lib/Frontend/CompilerInvocation.cpp

@@ -3738,6 +3738,7 @@ bool CompilerInvocation::parseArgs(
     SILOpts.SkipFunctionBodies = FunctionBodySkipping::None;
     SILOpts.CMOMode = CrossModuleOptimizationMode::Everything;
     SILOpts.EmbeddedSwift = true;
+    SILOpts.UseAggressiveReg2MemForCodeSize = true;
     // OSSA modules are required for deinit de-virtualization.
     SILOpts.EnableOSSAModules = true;
     // -g is promoted to -gdwarf-types in embedded Swift
@@ -3751,6 +3752,11 @@ bool CompilerInvocation::parseArgs(
     }
   }
 
+  SILOpts.UseAggressiveReg2MemForCodeSize =
+    ParsedArgs.hasFlag(OPT_enable_aggressive_reg2mem,
+                       OPT_disable_aggressive_reg2mem,
+                       SILOpts.UseAggressiveReg2MemForCodeSize);
+
   // With Swift 6, enable @_spiOnly by default. This also enables proper error
   // reporting of ioi references from spi decls.
   if (LangOpts.EffectiveLanguageVersion.isVersionAtLeast(6)) {