spirv-fuzz: Implement MaybeApplyTransformation helper function (#3540)

This function can be used to apply a transformation only if it is
applicable and use it wherever this pattern is used.

Fixes #3530.

source/fuzz/fuzzer_pass.h

@@ -103,6 +103,17 @@ class FuzzerPass {
     *GetTransformations()->add_transformation() = transformation.ToMessage();
   }
 
+  // A generic helper for applying a transformation only if it is applicable.
+  // If it is applicable, the transformation is applied and then added to the
+  // sequence of applied transformations. Otherwise, nothing happens.
+  void MaybeApplyTransformation(const Transformation& transformation) {
+    if (transformation.IsApplicable(GetIRContext(),
+                                    *GetTransformationContext())) {
+      transformation.Apply(GetIRContext(), GetTransformationContext());
+      *GetTransformations()->add_transformation() = transformation.ToMessage();
+    }
+  }
+
   // Returns the id of an OpTypeBool instruction.  If such an instruction does
   // not exist, a transformation is applied to add it.
   uint32_t FindOrCreateBoolType();

source/fuzz/fuzzer_pass_add_dead_blocks.cpp

@@ -59,11 +59,7 @@ void FuzzerPassAddDeadBlocks::Apply() {
   }
   // Apply all those transformations that are in fact applicable.
   for (auto& transformation : candidate_transformations) {
-    if (transformation.IsApplicable(GetIRContext(),
+    MaybeApplyTransformation(transformation);
-                                    *GetTransformationContext())) {
-      transformation.Apply(GetIRContext(), GetTransformationContext());
-      *GetTransformations()->add_transformation() = transformation.ToMessage();
-    }
   }
 }
 

source/fuzz/fuzzer_pass_add_dead_breaks.cpp

@@ -114,12 +114,9 @@ void FuzzerPassAddDeadBreaks::Apply() {
     candidate_transformations.erase(candidate_transformations.begin() + index);
     // Probabilistically decide whether to try to apply it vs. ignore it, in the
     // case that it is applicable.
-    if (transformation.IsApplicable(GetIRContext(),
+    if (GetFuzzerContext()->ChoosePercentage(
-                                    *GetTransformationContext()) &&
-        GetFuzzerContext()->ChoosePercentage(
             GetFuzzerContext()->GetChanceOfAddingDeadBreak())) {
-      transformation.Apply(GetIRContext(), GetTransformationContext());
+      MaybeApplyTransformation(transformation);
-      *GetTransformations()->add_transformation() = transformation.ToMessage();
     }
   }
 }

source/fuzz/fuzzer_pass_add_dead_continues.cpp

@@ -80,14 +80,9 @@ void FuzzerPassAddDeadContinues::Apply() {
           block.id(), condition_value, std::move(phi_ids));
       // Probabilistically decide whether to apply the transformation in the
       // case that it is applicable.
-      if (candidate_transformation.IsApplicable(GetIRContext(),
+      if (GetFuzzerContext()->ChoosePercentage(
-                                                *GetTransformationContext()) &&
-          GetFuzzerContext()->ChoosePercentage(
               GetFuzzerContext()->GetChanceOfAddingDeadContinue())) {
-        candidate_transformation.Apply(GetIRContext(),
+        MaybeApplyTransformation(candidate_transformation);
-                                       GetTransformationContext());
-        *GetTransformations()->add_transformation() =
-            candidate_transformation.ToMessage();
       }
     }
   }

source/fuzz/fuzzer_pass_interchange_zero_like_constants.cpp

@@ -111,13 +111,8 @@ void FuzzerPassInterchangeZeroLikeConstants::Apply() {
 
   // Replace the ids
   for (auto use_to_replace : uses_to_replace) {
-    auto transformation = TransformationReplaceIdWithSynonym(
+    MaybeApplyTransformation(TransformationReplaceIdWithSynonym(
-        use_to_replace.first, use_to_replace.second);
+        use_to_replace.first, use_to_replace.second));
-    if (transformation.IsApplicable(GetIRContext(),
-                                    *GetTransformationContext())) {
-      transformation.Apply(GetIRContext(), GetTransformationContext());
-      *GetTransformations()->add_transformation() = transformation.ToMessage();
-    }
   }
 }
 }  // namespace fuzz

source/fuzz/fuzzer_pass_merge_blocks.cpp

@@ -56,11 +56,7 @@ void FuzzerPassMergeBlocks::Apply() {
     uint32_t index = GetFuzzerContext()->RandomIndex(potential_transformations);
     auto transformation = potential_transformations.at(index);
     potential_transformations.erase(potential_transformations.begin() + index);
-    if (transformation.IsApplicable(GetIRContext(),
+    MaybeApplyTransformation(transformation);
-                                    *GetTransformationContext())) {
-      transformation.Apply(GetIRContext(), GetTransformationContext());
-      *GetTransformations()->add_transformation() = transformation.ToMessage();
-    }
   }
 }
 

source/fuzz/fuzzer_pass_outline_functions.cpp

@@ -89,11 +89,7 @@ void FuzzerPassOutlineFunctions::Apply() {
         /*new_callee_result_id*/ GetFuzzerContext()->GetFreshId(),
         /*input_id_to_fresh_id*/ std::move(input_id_to_fresh_id),
         /*output_id_to_fresh_id*/ std::move(output_id_to_fresh_id));
-    if (transformation.IsApplicable(GetIRContext(),
+    MaybeApplyTransformation(transformation);
-                                    *GetTransformationContext())) {
-      transformation.Apply(GetIRContext(), GetTransformationContext());
-      *GetTransformations()->add_transformation() = transformation.ToMessage();
-    }
   }
 }
 

source/fuzz/fuzzer_pass_split_blocks.cpp

@@ -96,11 +96,7 @@ void FuzzerPassSplitBlocks::Apply() {
     // If the position we have chosen turns out to be a valid place to split
     // the block, we apply the split. Otherwise the block just doesn't get
     // split.
-    if (transformation.IsApplicable(GetIRContext(),
+    MaybeApplyTransformation(transformation);
-                                    *GetTransformationContext())) {
-      transformation.Apply(GetIRContext(), GetTransformationContext());
-      *GetTransformations()->add_transformation() = transformation.ToMessage();
-    }
   }
 }