Narrow loop unroll in SPIR-V passes

Author: AnastaZIuk

include/spirv-tools/optimizer.hpp

@@ -125,6 +125,8 @@ class SPIRV_TOOLS_EXPORT Optimizer {
   // interface are considered live and are not eliminated.
   Optimizer& RegisterLegalizationPasses();
   Optimizer& RegisterLegalizationPasses(bool preserve_interface);
+  Optimizer& RegisterLegalizationPasses(bool preserve_interface,
+                                        bool include_loop_unroll);
 
   // 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

@@ -120,8 +120,9 @@ Optimizer& Optimizer::RegisterPass(PassToken&& p) {
 // The legalization problem is essentially a very general copy propagation
 // problem.  The optimization we use are all used to either do copy propagation
 // or enable more copy propagation.
-Optimizer& Optimizer::RegisterLegalizationPasses(bool preserve_interface) {
-  return
+Optimizer& Optimizer::RegisterLegalizationPasses(bool preserve_interface,
+                                                 bool include_loop_unroll) {
+  auto& optimizer =
       // Wrap OpKill instructions so all other code can be inlined.
       RegisterPass(CreateWrapOpKillPass())
           // Remove unreachable block so that merge return works.
@@ -154,34 +155,41 @@ Optimizer& Optimizer::RegisterLegalizationPasses(bool preserve_interface) {
           .RegisterPass(CreateLegalizeMultidimArrayPass())
           // Propagate constants to get as many constant conditions on branches
           // as possible.
-          .RegisterPass(CreateCCPPass())
-          .RegisterPass(CreateLoopUnrollPass(true))
-          .RegisterPass(CreateDeadBranchElimPass())
-          // Copy propagate members.  Cleans up code sequences generated by
-          // scalar replacement.  Also important for removing OpPhi nodes.
-          .RegisterPass(CreateSimplificationPass())
-          .RegisterPass(CreateAggressiveDCEPass(preserve_interface))
-          .RegisterPass(CreateCopyPropagateArraysPass())
-          // May need loop unrolling here see
-          // https://github.com/Microsoft/DirectXShaderCompiler/pull/930
-          // Get rid of unused code that contain traces of illegal code
-          // or unused references to unbound external objects
-          .RegisterPass(CreateVectorDCEPass())
-          .RegisterPass(CreateDeadInsertElimPass())
-          .RegisterPass(CreateReduceLoadSizePass())
-          .RegisterPass(CreateAggressiveDCEPass(preserve_interface))
-          .RegisterPass(CreateRemoveUnusedInterfaceVariablesPass())
-          .RegisterPass(CreateInterpolateFixupPass())
-          .RegisterPass(CreateInvocationInterlockPlacementPass())
-          .RegisterPass(CreateOpExtInstWithForwardReferenceFixupPass());
+          .RegisterPass(CreateCCPPass());
+  if (include_loop_unroll) {
+    optimizer.RegisterPass(CreateLoopUnrollPass(true));
+  }
+  return optimizer
+      .RegisterPass(CreateDeadBranchElimPass())
+      // Copy propagate members.  Cleans up code sequences generated by
+      // scalar replacement.  Also important for removing OpPhi nodes.
+      .RegisterPass(CreateSimplificationPass())
+      .RegisterPass(CreateAggressiveDCEPass(preserve_interface))
+      .RegisterPass(CreateCopyPropagateArraysPass())
+      // May need loop unrolling here see
+      // https://github.com/Microsoft/DirectXShaderCompiler/pull/930
+      // Get rid of unused code that contain traces of illegal code
+      // or unused references to unbound external objects
+      .RegisterPass(CreateVectorDCEPass())
+      .RegisterPass(CreateDeadInsertElimPass())
+      .RegisterPass(CreateReduceLoadSizePass())
+      .RegisterPass(CreateAggressiveDCEPass(preserve_interface))
+      .RegisterPass(CreateRemoveUnusedInterfaceVariablesPass())
+      .RegisterPass(CreateInterpolateFixupPass())
+      .RegisterPass(CreateInvocationInterlockPlacementPass())
+      .RegisterPass(CreateOpExtInstWithForwardReferenceFixupPass());
 }
 
 Optimizer& Optimizer::RegisterLegalizationPasses() {
-  return RegisterLegalizationPasses(false);
+  return RegisterLegalizationPasses(false, true);
+}
+
+Optimizer& Optimizer::RegisterLegalizationPasses(bool preserve_interface) {
+  return RegisterLegalizationPasses(preserve_interface, true);
 }
 
 Optimizer& Optimizer::RegisterPerformancePasses(bool preserve_interface) {
-  return RegisterPass(CreateWrapOpKillPass())
+  auto& optimizer = RegisterPass(CreateWrapOpKillPass())
       .RegisterPass(CreateDeadBranchElimPass())
       .RegisterPass(CreateMergeReturnPass())
       .RegisterPass(CreateInlineExhaustivePass())
@@ -199,11 +207,10 @@ Optimizer& Optimizer::RegisterPerformancePasses(bool preserve_interface) {
       .RegisterPass(CreateLocalMultiStoreElimPass())
       .RegisterPass(CreateAggressiveDCEPass(preserve_interface))
       .RegisterPass(CreateCCPPass())
-      .RegisterPass(CreateAggressiveDCEPass(preserve_interface))
-      .RegisterPass(CreateLoopUnrollPass(true))
-      .RegisterPass(CreateDeadBranchElimPass())
-      .RegisterPass(CreateRedundancyEliminationPass())
-      .RegisterPass(CreateCombineAccessChainsPass())
+      .RegisterPass(CreateAggressiveDCEPass(preserve_interface));
+  optimizer.RegisterPass(CreateDeadBranchElimPass());
+  optimizer.RegisterPass(CreateLocalRedundancyEliminationPass());
+  optimizer.RegisterPass(CreateCombineAccessChainsPass())
       .RegisterPass(CreateSimplificationPass())
       .RegisterPass(CreateScalarReplacementPass(0))
       .RegisterPass(CreateLocalAccessChainConvertPass())
@@ -220,9 +227,9 @@ Optimizer& Optimizer::RegisterPerformancePasses(bool preserve_interface) {
       .RegisterPass(CreateCopyPropagateArraysPass())
       .RegisterPass(CreateReduceLoadSizePass())
       .RegisterPass(CreateAggressiveDCEPass(preserve_interface))
-      .RegisterPass(CreateBlockMergePass())
-      .RegisterPass(CreateRedundancyEliminationPass())
-      .RegisterPass(CreateDeadBranchElimPass())
+      .RegisterPass(CreateBlockMergePass());
+  optimizer.RegisterPass(CreateLocalRedundancyEliminationPass());
+  return optimizer.RegisterPass(CreateDeadBranchElimPass())
       .RegisterPass(CreateBlockMergePass())
       .RegisterPass(CreateSimplificationPass());
 }