Base LexicalLifetimes dflt on SILOpts::CopyProp.

Previously, the default value for SILOptions::LexicalLifetimes was based
on a copy propagation behavior (which can then be overridden by the
flags for lexical lifetimems) only when the copy propagation was
explicitly specified.  Instead, set base the default value for this
option (SILOptions::LexicalLifetimes) on the effective copy propagation
behavior (i.e. SILOptions::CopyPropagation) regardless of whether an
explicit behavior has been specified.

Doing so will ensure that the desired behavior occurs as the default
behavior for copy-propagation changes, but for now this change is NFC.

Author: nate-chandler

lib/Frontend/CompilerInvocation.cpp

@@ -1522,13 +1522,14 @@ static bool ParseSILArgs(SILOptions &Opts, ArgList &Args,
     return true;
   }
 
-  // -enable-copy-propagation implies -enable-lexical-lifetimes unless
-  // otherwise specified.
-  if (Args.hasArg(OPT_enable_copy_propagation))
+  // Unless overridden below, enabling copy propagation means enabling lexical
+  // lifetimes.
+  if (Opts.CopyPropagation == CopyPropagationOption::On)
     Opts.LexicalLifetimes = LexicalLifetimesOption::On;
 
-  // -disable-copy-propagation implies -enable-lexical-lifetimes=false
-  if (Args.hasArg(OPT_disable_copy_propagation))
+  // Unless overridden below, disable copy propagation means disabling lexical
+  // lifetimes.
+  if (Opts.CopyPropagation == CopyPropagationOption::Off)
     Opts.LexicalLifetimes = LexicalLifetimesOption::DiagnosticMarkersOnly;
 
   // If move-only is enabled, always enable lexical lifetime as well.  Move-only

tools/sil-opt/SILOpt.cpp

@@ -537,9 +537,14 @@ int main(int argc, char **argv) {
     SILOpts.CopyPropagation = CopyPropagationOption::RequestedPassesOnly;
   }
 
-  if (EnableCopyPropagation)
+  // Unless overridden below, enabling copy propagation means enabling lexical
+  // lifetimes.
+  if (SILOpts.CopyPropagation == CopyPropagationOption::On)
     SILOpts.LexicalLifetimes = LexicalLifetimesOption::On;
-  if (DisableCopyPropagation)
+
+  // Unless overridden below, disable copy propagation means disabling lexical
+  // lifetimes.
+  if (SILOpts.CopyPropagation == CopyPropagationOption::Off)
     SILOpts.LexicalLifetimes = LexicalLifetimesOption::DiagnosticMarkersOnly;
 
   // Enable lexical lifetimes if it is set or if experimental move only is