Add a feature for allowing LocalSizeId (#4492)

Allow LocalSizeId as a way of sizing compute workgroups where the
environment allows it. A command-line switch is also added to force
acceptance even where the environment would not otherwise allow it.

include/spirv-tools/libspirv.h

@@ -659,6 +659,11 @@ SPIRV_TOOLS_EXPORT void spvValidatorOptionsSetWorkgroupScalarBlockLayout(
 SPIRV_TOOLS_EXPORT void spvValidatorOptionsSetSkipBlockLayout(
     spv_validator_options options, bool val);
 
+// Records whether or not the validator should allow the LocalSizeId
+// decoration where the environment otherwise would not allow it.
+SPIRV_TOOLS_EXPORT void spvValidatorOptionsSetAllowLocalSizeId(
+    spv_validator_options options, bool val);
+
 // Creates an optimizer options object with default options. Returns a valid
 // options object. The object remains valid until it is passed into
 // |spvOptimizerOptionsDestroy|.

include/spirv-tools/libspirv.hpp

@@ -115,6 +115,12 @@ class ValidatorOptions {
     spvValidatorOptionsSetSkipBlockLayout(options_, val);
   }
 
+  // Enables LocalSizeId decorations where the environment would not otherwise
+  // allow them.
+  void SetAllowLocalSizeId(bool val) {
+    spvValidatorOptionsSetAllowLocalSizeId(options_, val);
+  }
+
   // Records whether or not the validator should relax the rules on pointer
   // usage in logical addressing mode.
   //

source/spirv_validator_options.cpp

@@ -120,3 +120,8 @@ void spvValidatorOptionsSetSkipBlockLayout(spv_validator_options options,
                                            bool val) {
   options->skip_block_layout = val;
 }
+
+void spvValidatorOptionsSetAllowLocalSizeId(spv_validator_options options,
+                                            bool val) {
+  options->allow_localsizeid = val;
+}

source/spirv_validator_options.h

@@ -47,6 +47,7 @@ struct spv_validator_options_t {
         scalar_block_layout(false),
         workgroup_scalar_block_layout(false),
         skip_block_layout(false),
+        allow_localsizeid(false),
         before_hlsl_legalization(false) {}
 
   validator_universal_limits_t universal_limits_;
@@ -57,6 +58,7 @@ struct spv_validator_options_t {
   bool scalar_block_layout;
   bool workgroup_scalar_block_layout;
   bool skip_block_layout;
+  bool allow_localsizeid;
   bool before_hlsl_legalization;
 };
 

source/val/validate_mode_setting.cpp

@@ -225,6 +225,13 @@ spv_result_t ValidateEntryPoint(ValidationState_t& _, const Instruction* inst) {
                 }
               }
             }
+            if (i.opcode() == SpvOpExecutionModeId) {
+              const auto mode = i.GetOperandAs<SpvExecutionMode>(1);
+              if (mode == SpvExecutionModeLocalSizeId) {
+                ok = true;
+                break;
+              }
+            }
           }
           if (!ok) {
             return _.diag(SPV_ERROR_INVALID_DATA, inst)
@@ -429,6 +436,10 @@ spv_result_t ValidateExecutionMode(ValidationState_t& _,
       break;
     case SpvExecutionModeLocalSize:
     case SpvExecutionModeLocalSizeId:
+      if (mode == SpvExecutionModeLocalSizeId && !_.IsLocalSizeIdAllowed())
+        return _.diag(SPV_ERROR_INVALID_DATA, inst)
+               << "LocalSizeId mode is not allowed by the current environment.";
+
       if (!std::all_of(models->begin(), models->end(),
                        [&_](const SpvExecutionModel& model) {
                          switch (model) {

source/val/validation_state.cpp

@@ -175,6 +175,9 @@ ValidationState_t::ValidationState_t(const spv_const_context ctx,
     }
   }
 
+  // LocalSizeId is always allowed in non-Vulkan environments.
+  features_.env_allow_localsizeid = !spvIsVulkanEnv(env);
+
   // Only attempt to count if we have words, otherwise let the other validation
   // fail and generate an error.
   if (num_words > 0) {

source/val/validation_state.h

@@ -121,6 +121,9 @@ class ValidationState_t {
 
     // SPIR-V 1.4 allows Function and Private variables to be NonWritable
     bool nonwritable_var_in_function_or_private = false;
+
+    // Whether LocalSizeId execution mode is allowed by the environment.
+    bool env_allow_localsizeid = false;
   };
 
   ValidationState_t(const spv_const_context context,
@@ -493,6 +496,12 @@ class ValidationState_t {
     return features_.env_relaxed_block_layout || options()->relax_block_layout;
   }
 
+  // Returns true if allowing localsizeid, either because the environment always
+  // allows it, or because it is enabled from the command-line.
+  bool IsLocalSizeIdAllowed() const {
+    return features_.env_allow_localsizeid || options()->allow_localsizeid;
+  }
+
   /// Sets the struct nesting depth for a given struct ID
   void set_struct_nesting_depth(uint32_t id, uint32_t depth) {
     struct_nesting_depth_[id] = depth;

tools/val/val.cpp

@@ -64,6 +64,8 @@ Options:
   --relax-struct-store             Allow store from one struct type to a
                                    different type with compatible layout and
                                    members.
+  --allow-localsizeid              Allow use of the LocalSizeId decoration where it would otherwise not
+                                   be allowed by the target environment.
   --before-hlsl-legalization       Allows code patterns that are intended to be
                                    fixed by spirv-opt's legalization passes.
   --version                        Display validator version information.
@@ -153,6 +155,8 @@ int main(int argc, char** argv) {
         options.SetWorkgroupScalarBlockLayout(true);
       } else if (0 == strcmp(cur_arg, "--skip-block-layout")) {
         options.SetSkipBlockLayout(true);
+      } else if (0 == strcmp(cur_arg, "--allow-localsizeid")) {
+        options.SetAllowLocalSizeId(true);
       } else if (0 == strcmp(cur_arg, "--relax-struct-store")) {
         options.SetRelaxStructStore(true);
       } else if (0 == cur_arg[1]) {