Update max private mem used by each function group while having VLA

Update max private mem used by each function group when function group has VariableLengthAlloca.

(cherry picked from commit 25cda17)

Author: kcyganik1

IGC/Compiler/Optimizer/OpenCLPasses/PrivateMemory/PrivateMemoryResolution.cpp

@@ -291,8 +291,13 @@ bool PrivateMemoryResolution::runOnModule(llvm::Module& M)
             }
             if (FG->hasVariableLengthAlloca())
             {
-                // Add another 1KB if there are VLAs
-                maxPrivateMem += 1024;
+                // Add another 4KB if there are VLAs
+                maxPrivateMem += 4096;
+                std::string maxPrivateMemValue = std::to_string(maxPrivateMem);
+                std::string fullWarningMessage = "VLA has been detected, the private memory size is set to " + maxPrivateMemValue + "B. You can change the size by setting flag ForcePerThreadPrivateMemorySize to a value from [1024:20480]. Greater values can affect performance, and lower ones may lead to incorrect results of your program";
+
+                // Now, you can pass the concatenated warning message (const char*) to the EmitWarning function
+                getAnalysis<CodeGenContextWrapper>().getCodeGenContext()->EmitWarning(fullWarningMessage.c_str());
             }
             maxPrivateMem = std::max(maxPrivateMem, Ctx.getPrivateMemoryMinimalSizePerThread());
             maxPrivateMem = std::max(maxPrivateMem, (uint32_t)(IGC_GET_FLAG_VALUE(ForcePerThreadPrivateMemorySize)));