Add variable pointer support to IsValidBasePointer

Fixes #1729

* Adds supported opcodes to IsValidBasePointer() enable by
VariablePointers and VariablePointersStorageBuffer capabilities
 * Added tests

2 files changed, 27 insertions, 7 deletions

diff --git a/source/opt/instruction.cpp b/source/opt/instruction.cpp
index af61bf19..12026846 100644
--- a/source/opt/instruction.cpp
+++ b/source/opt/instruction.cpp
@@ -419,7 +419,8 @@ bool Instruction::IsValidBasePointer() const {
     return false;
   }
 
-  if (context()->get_feature_mgr()->HasCapability(SpvCapabilityAddresses)) {
+  auto feature_mgr = context()->get_feature_mgr();
+  if (feature_mgr->HasCapability(SpvCapabilityAddresses)) {
     // TODO: The rules here could be more restrictive.
     return true;
   }
@@ -428,6 +429,25 @@ bool Instruction::IsValidBasePointer() const {
     return true;
   }
 
+  // With variable pointers, there are more valid base pointer objects.
+  // Variable pointers implicitly declares Variable pointers storage buffer.
+  SpvStorageClass storage_class =
+      static_cast<SpvStorageClass>(type->GetSingleWordInOperand(0));
+  if ((feature_mgr->HasCapability(SpvCapabilityVariablePointersStorageBuffer) &&
+       storage_class == SpvStorageClassStorageBuffer) ||
+      (feature_mgr->HasCapability(SpvCapabilityVariablePointers) &&
+       storage_class == SpvStorageClassWorkgroup)) {
+    switch (opcode()) {
+      case SpvOpPhi:
+      case SpvOpSelect:
+      case SpvOpFunctionCall:
+      case SpvOpConstantNull:
+        return true;
+      default:
+        break;
+    }
+  }
+
   uint32_t pointee_type_id = type->GetSingleWordInOperand(1);
   Instruction* pointee_type_inst =
       context()->get_def_use_mgr()->GetDef(pointee_type_id);
diff --git a/source/opt/instruction.h b/source/opt/instruction.h
index 812c4831..e6528ee5 100644
--- a/source/opt/instruction.h
+++ b/source/opt/instruction.h
@@ -415,6 +415,12 @@ class Instruction : public utils::IntrusiveNodeBase<Instruction> {
   // Return true if the only effect of this instructions is the result.
   bool IsOpcodeSafeToDelete() const;
 
+  // Returns true if it is valid to use the result of |inst| as the base
+  // pointer for a load or store.  In this case, valid is defined by the relaxed
+  // logical addressing rules when using logical addressing.  Normal validation
+  // rules for physical addressing.
+  bool IsValidBasePointer() const;
+
  private:
   // Returns the total count of result type id and result id.
   uint32_t TypeResultIdCount() const {
@@ -427,12 +433,6 @@ class Instruction : public utils::IntrusiveNodeBase<Instruction> {
   bool IsReadOnlyVariableShaders() const;
   bool IsReadOnlyVariableKernel() const;
 
-  // Returns true if it is valid to use the result of |inst| as the base
-  // pointer for a load or store.  In this case, valid is defined by the relaxed
-  // logical addressing rules when using logical addressing.  Normal validation
-  // rules for physical addressing.
-  bool IsValidBasePointer() const;
-
   // Returns true if the result of |inst| can be used as the base image for an
   // instruction that samples a image, reads an image, or writes to an image.
   bool IsValidBaseImage() const;