Remove .parameter directive from vISA assembly.

Remove .parameter directive from vISA assembly as vISA stack functions are not
allowed to have parameters. Assert in CreateVISAInputVars if it's called by
a non-kenrel function.

Also add comments to describe vISA assembly structure and the meanings for each
directive.

Author: Wei-Chen-Intel

visa/CISA.l

@@ -171,7 +171,6 @@ static void                    appendStringLiteralChar(char c, char *buf, size_t
         CISAlval.string[yyleng] = '\0';
         return DIRECTIVE_IMPLICIT;
     }
-".parameter"        {TRACE("** PARAMETER"); return DIRECTIVE_PARAMETER;}
 ".function"         {TRACE("** FUNCTION"); return DIRECTIVE_FUNC;}
 ".global_function"  {TRACE("** GLOBAL FUNCTION"); return DIRECTIVE_GLOBAL_FUNC;}
 ".kernel"           {TRACE("** KERNEL NAME DIRECTIVE"); return DIRECTIVE_KERNEL;}

visa/CISA.y

@@ -26,7 +26,6 @@ static int lscCheckExecSize(
     LSC_DATA_ORDER data_order,
     int exec_size);
 
-//VISA_Type variable_declaration_and_type_check(char *var, Common_ISA_Var_Class type);
 void CISAerror(CISA_IR_Builder* builder, char const* msg);
 int yylex(CISA_IR_Builder *pBuilder);
 extern int CISAlineno;
@@ -37,9 +36,6 @@ static VISA_Align AlignBytesToVisaAlignment(int bytes);
 static int DataTypeSizeOf(VISA_Type type);
 static bool ParseEMask(const char* sym, VISA_EMask_Ctrl &emask);
 
-
-
-
 //
 // check if the cond is true.
 // if cond is false, then print errorMessage (syntax error) and YYABORT
@@ -64,9 +60,7 @@ static bool ParseEMask(const char* sym, VISA_EMask_Ctrl &emask);
     } while (0)
 
 std::deque<const char*> switchLabels;
-char * switch_label_array[32];
 std::vector<VISA_opnd*> RTRWOperandsVec;
-int num_parameters;
 
 VISA_RawOpnd* rawOperandArray[16];
 
@@ -300,8 +294,7 @@ std::vector<attr_gen_struct*> AttrOptVar;
 %token          DIRECTIVE_INPUT       // .input
 %token          DIRECTIVE_KERNEL      // .kernel
 %token          DIRECTIVE_KERNEL_ATTR // .kernel_attr
-%token          DIRECTIVE_PARAMETER   // .parameter
-%token          DIRECTIVE_VERSION     // .verions
+%token          DIRECTIVE_VERSION     // .version
 
 // tokens to support .decl and .input
 %token ALIAS_EQ             // .decl ... alias=...
@@ -675,7 +668,6 @@ Statement:
     | DirectiveGlobalFunction
     | DirectiveImplicitInput
     | DirectiveInput
-    | DirectiveParameter
     | DirectiveFunc
     | DirectiveAttr
     | Instruction
@@ -816,13 +808,6 @@ InputOffset: %empty {$$ = 0;} | OFFSET_EQ IntExp {$$ = $2;}
 InputSize: SIZE_EQ IntExp {$$ = $2;}
 
 ///////////////////////////////////////////////////////////
-// ----- .parameter ------
-
-DirectiveParameter:
-    //      1            2       3        4
-    DIRECTIVE_PARAMETER IDENT InputSize GenAttrOpt {
-        ABORT_ON_FAIL(pBuilder->CISA_input_directive($2, 0, (unsigned short)$3, CISAlineno));
-    }
 // ----- .attribute ------
 
 DirectiveAttr:

visa/IsaDisassembly.cpp

@@ -6,10 +6,36 @@ SPDX-License-Identifier: MIT
 
 ============================= end_copyright_notice ===========================*/
 
-/*
- * vISA IR Disassembler
- *
- */
+//
+// vISA IR Disassembler
+//
+// A vISA assembly file (.visaasm) has one or more kernels and global functions.
+//
+// A kernel (.kernel) represents an entry point of GPU execution. It may only be
+// invoked from the host program.
+//
+// A global function (.global_function) may be invoked by a kernel or another
+// function through the FCALL/IFCALL instruction.
+//
+// Each kernel or function contains a number of variables (.decl). By default
+// the declares are printed at the top of the kernel/function (i.e., they are
+// visible everywhere inside the function), though they can also be interleaved
+// with the instructions so long as each variable is declared before its use.
+// C-style block scope support also exists with the {} operator.
+//
+// A kernel may declare input variables via the .input directive, which also
+// binds the variable to a fixed GRF location. Input variables are considered
+// live-in to the kernel.
+//
+// Each kernel/function may declare a number of attributes (.kernel_attr
+// directive) to communicate additional information about the function. They
+// have to be declared before any instructions in the function.
+//
+// A kernel/function's instructions are organized into subroutines (.function)
+// that are invoked through the CALL instruction. By convention the first
+// subroutine represents the entry point of the kernel/function, and it may not
+// be the target of a CALL.
+//
 
 #include "IGC/common/StringMacros.hpp"
 #include <algorithm>
@@ -478,16 +504,13 @@ std::string printSurfaceDecl(const print_format_provider_t *header,
 }
 
 std::string printFuncInput(const print_format_provider_t *header,
-                           unsigned declID, bool isKernel,
-                           const Options *options) {
+                           unsigned declID, const Options *options) {
   vISA_ASSERT_INPUT(header, "Argument Exception: argument header is NULL.");
   std::stringstream sstr;
 
   const input_info_t *input = header->getInput(declID);
-  if (!isKernel) {
-    sstr << ".parameter " /* function */;
-  } else if (!input->getImplicitKind()) {
-    sstr << ".input " /* kernel */;
+  if (!input->getImplicitKind()) {
+    sstr << ".input ";
   } else {
     sstr << input->getImplicitKindString() << " ";
   }
@@ -499,9 +522,7 @@ std::string printFuncInput(const print_format_provider_t *header,
     sstr << Input_Class_String[input->getInputClass()] << input->index;
   }
 
-  if (isKernel)
-    sstr << " offset=" << input->offset;
-
+  sstr << " offset=" << input->offset;
   sstr << " size=" << input->size;
 
   return sstr.str();
@@ -3287,7 +3308,7 @@ std::string VISAKernel_format_provider::printKernelHeader(bool printVersion) {
   }
   // inputs to kernel
   for (unsigned i = 0; i < getInputCount(); i++) {
-    sstr << "\n" << printFuncInput(this, i, isKernel, options);
+    sstr << "\n" << printFuncInput(this, i, options);
   }
 
   bool isTargetSet = false;

visa/IsaDisassembly.h

@@ -32,8 +32,7 @@ std::string printSamplerDecl(const print_format_provider_t *header,
 std::string printSurfaceDecl(const print_format_provider_t *header,
                              unsigned declID, unsigned numPredefinedSurfaces);
 std::string printFuncInput(const print_format_provider_t *header,
-                           unsigned declID, bool isKernel,
-                           const Options *options);
+                           unsigned declID, const Options *options);
 std::string printOneAttribute(const print_format_provider_t *kernel,
                               const attribute_info_t *attr);
 // Used for printing non-kernel attributes

visa/VISAKernelImpl.cpp

@@ -1659,6 +1659,11 @@ int VISAKernelImpl::CreateVISAInputVar(CISA_GEN_VAR *decl, uint16_t offset,
                                        uint16_t size, uint8_t implicitKind) {
   TIME_SCOPE(VISA_BUILDER_CREATE_VAR);
 
+  if (!getIsKernel()) {
+    vISA_ASSERT(false, "only kernels may have input variables");
+    return VISA_FAILURE;
+  }
+
   unsigned int status = VISA_SUCCESS;
   input_info_t *input = (input_info_t *)m_mem.alloc(sizeof(input_info_t));
   input->kind = GetInputClass(decl->type);
@@ -1708,7 +1713,7 @@ int VISAKernelImpl::CreateVISAInputVar(CISA_GEN_VAR *decl, uint16_t offset,
         VISAKernel_format_provider fmt(this);
         m_CISABuilder->m_ssIsaAsm
             << printFuncInput(&fmt, m_printDeclIndex.input_index++,
-                              getIsKernel(), getOptions())
+                              getOptions())
             << "\n";
       }
     }