From b0c6943121f186c79d2152694d209f82904ff1e1 Mon Sep 17 00:00:00 2001
From: Andreas Baumann <mail@andreasbaumann.cc>
Date: Thu, 30 Sep 2021 17:03:17 +0200
Subject: cc: rearanged for a pseudo-main

---
 miniany/cc.c | 77 ++++++++++++++++++++++++++++++++++++++++--------------------
 1 file changed, 52 insertions(+), 25 deletions(-)

(limited to 'miniany/cc.c')

diff --git a/miniany/cc.c b/miniany/cc.c
index cef1af2..5cf2f9c 100644
--- a/miniany/cc.c
+++ b/miniany/cc.c
@@ -487,6 +487,7 @@ struct Parser {
 	int token;
 	struct Scanner *scanner;
 	struct Scope *global_scope;
+	int debug;
 };
 
 struct Generator {
@@ -940,6 +941,10 @@ int generateFromAST( struct Generator *generator, struct ASTnode *node, int inre
 
 void genPrologue( struct Compiler *compiler )
 {
+	if( compiler->parser->debug ) {
+		putstring( "; prologue" );
+		putnl( );
+	}
 	putstring( "format binary" ); putnl( );
 	putstring( "use32" ); putnl( );
 	putstring( "org $1000000" ); putnl( );
@@ -968,15 +973,19 @@ void genPrologue( struct Compiler *compiler )
 	putstring( "mov edx, 11" ); putnl( );
 	putstring( "int 0x80" ); putnl( );
 	putstring( "ret" ); putnl( );
-	putstring( "_start:" ); putnl( );
 }
 
 void genEpilogue( struct Compiler *compiler )
 {
 	struct Symbol *sym;
 	
-	putstring( "hlt" );
-	putnl( );
+	if( compiler->parser->debug ) {
+		putstring( "; entry point" );
+		putnl( );
+	}
+	putstring( "_start:" ); putnl( );
+	putstring( "call main" ); putnl( );
+	putstring( "hlt" ); putnl( );
 	sym = compiler->parser->global_scope->sym;
 	while( sym != NULL ) {
 		genAddGlob( compiler->generator, sym->name );
@@ -995,6 +1004,7 @@ struct Parser *createParser( )
 	parser = (struct Parser *)malloc( sizeof( struct Parser ) );
 	parser->scanner = createScanner( );
 	parser->global_scope = createScope( "global" );
+	parser->debug = 0;
 	
 	return parser;
 }
@@ -1269,22 +1279,22 @@ void parseIf( struct Compiler *compiler )
 	parserExpect( parser, S_IF, "if" );
 	parserExpect( parser, S_LPAREN, "(" );
 	node = parseExpression( parser, 0 );
-	if( compiler->generator->debug ) {
+	if( parser->debug ) {
 		putstring( "; if <cond> then" ); putnl( );
 	}
 	generateFromAST( compiler->generator, node, NOREG );
 	/* TODO: this should be condensed and optimized for the normal path
 	 *       (rare ifs, invert the condition, jmpXX directly */
 	putstring( "cmp al, 0" ); putnl( );
+	genFreeAllRegs( compiler->generator );
 	label1 = genGetLabel( compiler, compiler->parser->global_scope );
 	putstring( "je " ); putstring( label1 ); putnl( );
-	genFreeAllRegs( compiler->generator );
 	parserExpect( parser, S_RPAREN, ")" );
 	parseStatementBlock( compiler );
 	if( parser->token == S_ELSE ) {
 		label2 = genGetLabel( compiler, compiler->parser->global_scope );
 		putstring( "jmp " ); putstring( label2 ); putnl( );
-		if( compiler->generator->debug ) {
+		if( parser->debug ) {
 			putstring( "; else" ); putnl( );
 		}
 		putstring( label1 ); putchar( ':' ); putnl( );
@@ -1296,7 +1306,7 @@ void parseIf( struct Compiler *compiler )
 		putstring( label1 ); putchar( ':' ); putnl( );
 	}
 		
-	if( compiler->generator->debug ) {
+	if( parser->debug ) {
 		putstring( "; fi" ); putnl( );
 	}
 	free( label1 );
@@ -1313,21 +1323,21 @@ void parseWhile( struct Compiler *compiler )
 	parserExpect( parser, S_WHILE, "while" );
 	parserExpect( parser, S_LPAREN, "(" );
 	node = parseExpression( parser, 0 );
-	if( compiler->generator->debug ) {
+	if( parser->debug ) {
 		putstring( "; while <cond>" ); putnl( );
 	}
 	label2 = genGetLabel( compiler, compiler->parser->global_scope );
 	putstring( label2 ); putchar( ':' ); putnl( );
 	generateFromAST( compiler->generator, node, NOREG );
 	putstring( "cmp al, 0" ); putnl( );
+	genFreeAllRegs( compiler->generator );
 	label1 = genGetLabel( compiler, compiler->parser->global_scope );
 	putstring( "je " ); putstring( label1 ); putnl( );
-	genFreeAllRegs( compiler->generator );
 	parserExpect( parser, S_RPAREN, ")" );
 	parseStatementBlock( compiler );
 	putstring( "jmp " ); putstring( label2 ); putnl( );
 	putstring( label1 ); putchar( ':' ); putnl( );
-	if( compiler->generator->debug ) {
+	if( parser->debug ) {
 		putstring( "; fi" ); putnl( );
 	}
 	free( label2 );
@@ -1342,7 +1352,7 @@ void parseDo( struct Compiler *compiler )
 
 	parser = compiler->parser;
 	parserExpect( parser, S_DO, "do" );
-	if( compiler->generator->debug ) {
+	if( parser->debug ) {
 		putstring( "; do" ); putnl( );
 	}
 	label1 = genGetLabel( compiler, compiler->parser->global_scope );
@@ -1353,25 +1363,13 @@ void parseDo( struct Compiler *compiler )
 	node = parseExpression( parser, 0 );
 	generateFromAST( compiler->generator, node, NOREG );
 	putstring( "cmp al, 0" ); putnl( );
-	putstring( "jne " ); putstring( label1 ); putnl( );
 	genFreeAllRegs( compiler->generator );
+	putstring( "jne " ); putstring( label1 ); putnl( );
 	parserExpect( parser, S_RPAREN, ")" );
 	parserExpect( parser, S_SEMICOLON, ";" );
 	free( label1 );
 }
 
-/*
-
-
-	putstring( "jmp " ); putstring( label2 ); putnl( );
-	putstring( label1 ); putchar( ':' ); putnl( );
-	if( compiler->generator->debug ) {
-		putstring( "; fi" ); putnl( );
-	}
-	free( label2 );
-	free( label1 );
-}
- */
 void parseStatement( struct Compiler *compiler )
 {
 	struct Parser *parser;
@@ -1413,6 +1411,34 @@ void parseStatementBlock( struct Compiler *compiler )
 	parserExpect( parser, S_RBRACE, "}" );
 }
 
+void parseFunctionDeclaraion( struct Compiler *compiler )
+{
+	struct Parser *parser;
+
+	parser = compiler->parser;
+	if( parser->token == S_IDENT ) {
+		if( strcmp( parser->scanner->ident, "void" ) != 0 ) {
+			scannerPrintErrorHeader( parser->scanner );
+			putstring( "expected void as return value of a function declaration" );
+			putnl( );
+			exit( EXIT_FAILURE );		
+		}
+	}
+	parser->token = getToken( parser->scanner );
+	if( parser->debug ) {
+		putstring( "; function declaration '" );
+		putstring( parser->scanner->ident );
+		putstring( "'" );
+		putnl( );
+	}
+	putstring( parser->scanner->ident ); putchar( ':' ); putnl( );
+	parser->token = getToken( compiler->parser->scanner );
+	parserExpect( parser, S_LPAREN, "(" );
+	parserExpect( parser, S_RPAREN, ")" );
+	parseStatementBlock( compiler );
+	putstring( "ret" ); putnl( );
+}
+
 /* compiler */
 
 struct Compiler *createCompiler( )
@@ -1441,10 +1467,11 @@ int main( int argc, char **argv )
 
 	compiler = createCompiler( );
 	/* compiler->parser->scanner->debug = 1; */
+	/* compiler->parser->debug = 1; */
 	/* compiler->generator->debug = 1; */
 	genPrologue( compiler );
 	compiler->parser->token = getToken( compiler->parser->scanner );
-	parseStatementBlock( compiler );
+	parseFunctionDeclaraion( compiler );
 	genEpilogue( compiler );
 	freeCompiler( compiler );
 	
-- 
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