[spirv] separate triggering legalization and passing before-legalize-hlsl (#3816)

`--before-legalize-hlsl` option for spirv-val must be used when the
SPIR-V code has to be legalized by spirv-opt but it is not legalized
i.e., "SPIR-V generated from HLSL before legalize". Therefore, we have
to run the legalization or pass the `--before-legalize-hlsl` option to
spirv-val but we do not need to do both. This CL lets DXC does not pass
`--before-legalize-hlsl` option when it legalizes the SPIR-V code.

Author: jaebaek

tools/clang/lib/SPIRV/SpirvEmitter.cpp

@@ -664,14 +664,16 @@ void SpirvEmitter::HandleTranslationUnit(ASTContext &context) {
   // Output the constructed module.
   std::vector<uint32_t> m = spvBuilder.takeModule();
 
-  if (!spirvOptions.codeGenHighLevel) {
-    // In order to flatten composite resources, we must also unroll loops.
-    // Therefore we should run legalization before optimization.
-    needsLegalization = needsLegalization ||
-                        declIdMapper.requiresLegalization() ||
-                        spirvOptions.flattenResourceArrays ||
-                        declIdMapper.requiresFlatteningCompositeResources();
-
+  // In order to flatten composite resources, we must also unroll loops.
+  // Therefore we should run legalization before optimization.
+  needsLegalization = needsLegalization ||
+                      declIdMapper.requiresLegalization() ||
+                      spirvOptions.flattenResourceArrays ||
+                      declIdMapper.requiresFlatteningCompositeResources();
+
+  if (spirvOptions.codeGenHighLevel) {
+    beforeHlslLegalization = needsLegalization;
+  } else {
     // Run legalization passes
     if (needsLegalization) {
       std::string messages;
@@ -2320,7 +2322,7 @@ SpirvInstruction *SpirvEmitter::processCall(const CallExpr *callExpr) {
         // the legalization.
         if (objInstr->getStorageClass() != spv::StorageClass::Function ||
             !isMemoryObjectDeclaration(objInstr))
-          beforeHlslLegalization = true;
+          needsLegalization = true;
 
         args.push_back(objInstr);
       }
@@ -2372,7 +2374,7 @@ SpirvInstruction *SpirvEmitter::processCall(const CallExpr *callExpr) {
       // to function. If we pass an argument that is not function scope
       // or not memory object declaration, we need the legalization.
       if (!argInfo || argInfo->getStorageClass() != spv::StorageClass::Function)
-        beforeHlslLegalization = true;
+        needsLegalization = true;
 
       isTempVar.push_back(false);
       args.push_back(argInst);
@@ -2423,9 +2425,6 @@ SpirvInstruction *SpirvEmitter::processCall(const CallExpr *callExpr) {
     }
   }
 
-  if (beforeHlslLegalization)
-    needsLegalization = true;
-
   assert(vars.size() == isTempVar.size());
   assert(vars.size() == args.size());
 
@@ -12305,8 +12304,7 @@ bool SpirvEmitter::spirvToolsValidate(std::vector<uint32_t> *mod,
                  const char *message) { *messages += message; });
 
   spvtools::ValidatorOptions options;
-  options.SetBeforeHlslLegalization(needsLegalization ||
-                                    declIdMapper.requiresLegalization());
+  options.SetBeforeHlslLegalization(beforeHlslLegalization);
   // GL: strict block layout rules
   // VK: relaxed block layout rules
   // DX: Skip block layout rules