Gate legalize SSA rewrite separately

Author: AnastaZIuk

include/spirv-tools/optimizer.hpp

@@ -126,7 +126,8 @@ class SPIRV_TOOLS_EXPORT Optimizer {
   Optimizer& RegisterLegalizationPasses();
   Optimizer& RegisterLegalizationPasses(bool preserve_interface);
   Optimizer& RegisterLegalizationPasses(bool preserve_interface,
-                                        bool include_loop_unroll);
+                                        bool include_loop_unroll,
+                                        bool include_ssa_rewrite);
 
   // Register passes specified in the list of |flags|.  Each flag must be a
   // string of a form accepted by Optimizer::FlagHasValidForm().

source/opt/optimizer.cpp

@@ -121,7 +121,8 @@ Optimizer& Optimizer::RegisterPass(PassToken&& p) {
 // problem.  The optimization we use are all used to either do copy propagation
 // or enable more copy propagation.
 Optimizer& Optimizer::RegisterLegalizationPasses(bool preserve_interface,
-                                                 bool include_loop_unroll) {
+                                                 bool include_loop_unroll,
+                                                 bool include_ssa_rewrite) {
   auto& optimizer =
       // Wrap OpKill instructions so all other code can be inlined.
       RegisterPass(CreateWrapOpKillPass())
@@ -148,11 +149,15 @@ Optimizer& Optimizer::RegisterLegalizationPasses(bool preserve_interface,
           // Takes care of copy propagation of non-members.
           .RegisterPass(CreateLocalSingleBlockLoadStoreElimPass())
           .RegisterPass(CreateLocalSingleStoreElimPass())
-          .RegisterPass(CreateAggressiveDCEPass(preserve_interface))
-          .RegisterPass(CreateLocalMultiStoreElimPass())
-          .RegisterPass(CreateCombineAccessChainsPass())
-          .RegisterPass(CreateAggressiveDCEPass(preserve_interface))
-          .RegisterPass(CreateLegalizeMultidimArrayPass())
+          .RegisterPass(CreateAggressiveDCEPass(preserve_interface));
+  if (include_ssa_rewrite) {
+    optimizer.RegisterPass(CreateLocalMultiStoreElimPass());
+  }
+  optimizer.RegisterPass(CreateCombineAccessChainsPass());
+  if (include_ssa_rewrite) {
+    optimizer.RegisterPass(CreateAggressiveDCEPass(preserve_interface));
+  }
+  optimizer.RegisterPass(CreateLegalizeMultidimArrayPass())
           // Propagate constants to get as many constant conditions on branches
           // as possible.
           .RegisterPass(CreateCCPPass());
@@ -181,11 +186,11 @@ Optimizer& Optimizer::RegisterLegalizationPasses(bool preserve_interface,
 }
 
 Optimizer& Optimizer::RegisterLegalizationPasses() {
-  return RegisterLegalizationPasses(false, true);
+  return RegisterLegalizationPasses(false, true, true);
 }
 
 Optimizer& Optimizer::RegisterLegalizationPasses(bool preserve_interface) {
-  return RegisterLegalizationPasses(preserve_interface, true);
+  return RegisterLegalizationPasses(preserve_interface, true, true);
 }
 
 Optimizer& Optimizer::RegisterPerformancePasses(bool preserve_interface) {