Minor refactoring[NFC]

Preparing for turning store combining for other APIs (
the existing code is for OCL only).

This change has no functional change.

Author: jgu222

IGC/Compiler/CISACodeGen/MemOpt.cpp

@@ -2586,6 +2586,10 @@ const BundleSize_t BundleConfig::m_d32VecSizes_u = { 2,3,4,8,16,32,64 };
 const BundleSize_t BundleConfig::m_d8VecSizes_u = { 2,4,8,16,32 };
 
 bool IGC::doLdStCombine(const CodeGenContext* CGC) {
+    // start with OCL, will apply to others.
+    if (CGC->type != ShaderType::OPENCL_SHADER)
+        return false;
+
     if (CGC->type == ShaderType::OPENCL_SHADER) {
        auto oclCtx = (const OpenCLProgramContext*)CGC;
        // internal flag overrides IGC key

IGC/Compiler/CISACodeGen/ShaderCodeGen.cpp

@@ -668,11 +668,8 @@ void AddLegalizationPasses(CodeGenContext& ctx, IGCPassManager& mpm, PSSignature
         if (IGC_IS_FLAG_ENABLED(EnableAdvMemOpt))
             mpm.add(createAdvMemOptPass());
 
-        if (doLdStCombine(&ctx) &&
-            ctx.type == ShaderType::OPENCL_SHADER)
-        {
-            // start with OCL, will apply to others.
-            //   Once it is stable, no split 64bit store/load anymore.
+        if (doLdStCombine(&ctx)) {
+            // Once it is stable, no split 64bit store/load anymore.
             mpm.add(createLdStCombinePass());
         }