[568]a: precise linenumbers for statements.

R=rsc, ken2, r, rsc1
CC=golang-dev
https://golang.org/cl/2297042

src/cmd/5a/a.h

@@ -148,6 +148,7 @@ EXTERN	int	pass;
 EXTERN	char*	pathname;
 EXTERN	int32	pc;
 EXTERN	int	peekc;
+EXTERN	int32	stmtline;
 EXTERN	int	sym;
 EXTERN	char*	symb;
 EXTERN	int	thechar;

src/cmd/5a/a.y

@@ -63,7 +63,11 @@
 %type	<gen>	imm ximm name oreg ireg nireg ioreg imsr
 %%
 prog:
-|	prog line
+|	prog
+	{
+		stmtline = lineno;
+	}
+	line
 
 line:
 	LLAB ':'

src/cmd/5a/lex.c

@@ -658,10 +658,10 @@ jackpot:
 	Bputc(&obuf, a);
 	Bputc(&obuf, scond);
 	Bputc(&obuf, reg);
-	Bputc(&obuf, lineno);
-	Bputc(&obuf, lineno>>8);
-	Bputc(&obuf, lineno>>16);
-	Bputc(&obuf, lineno>>24);
+	Bputc(&obuf, stmtline);
+	Bputc(&obuf, stmtline>>8);
+	Bputc(&obuf, stmtline>>16);
+	Bputc(&obuf, stmtline>>24);
 	zaddr(g1, sf);
 	zaddr(g2, st);
 

src/cmd/6a/a.h

@@ -161,6 +161,7 @@ EXTERN	int	pass;
 EXTERN	char*	pathname;
 EXTERN	int32	pc;
 EXTERN	int	peekc;
+EXTERN	int32	stmtline;
 EXTERN	int	sym;
 EXTERN	char*	symb;
 EXTERN	int	thechar;

src/cmd/6a/a.y

@@ -60,7 +60,11 @@
 %type	<gen2>	spec1 spec2 spec3 spec4 spec5 spec6 spec7 spec8 spec9
 %%
 prog:
-|	prog line
+|	prog 
+	{
+		stmtline = lineno;
+	}
+	line
 
 line:
 	LLAB ':'

src/cmd/6a/lex.c

@@ -1260,10 +1260,10 @@ jackpot:
 	}
 	Bputc(&obuf, a);
 	Bputc(&obuf, a>>8);
-	Bputc(&obuf, lineno);
-	Bputc(&obuf, lineno>>8);
-	Bputc(&obuf, lineno>>16);
-	Bputc(&obuf, lineno>>24);
+	Bputc(&obuf, stmtline);
+	Bputc(&obuf, stmtline>>8);
+	Bputc(&obuf, stmtline>>16);
+	Bputc(&obuf, stmtline>>24);
 	zaddr(&g2->from, sf);
 	zaddr(&g2->to, st);
 

src/cmd/8a/a.h

@@ -162,6 +162,7 @@ EXTERN	int	pass;
 EXTERN	char*	pathname;
 EXTERN	int32	pc;
 EXTERN	int	peekc;
+EXTERN	int32	stmtline;
 EXTERN	int	sym;
 EXTERN	char*	symb;
 EXTERN	int	thechar;

src/cmd/8a/a.y

@@ -64,7 +64,11 @@
 %type	<gen2>	spec1 spec2 spec3 spec4 spec5 spec6 spec7 spec8
 %%
 prog:
-|	prog line
+|	prog
+	{
+		stmtline = lineno;
+	}
+	line
 
 line:
 	LLAB ':'

src/cmd/8a/lex.c

@@ -925,10 +925,10 @@ jackpot:
 	}
 	Bputc(&obuf, a);
 	Bputc(&obuf, a>>8);
-	Bputc(&obuf, lineno);
-	Bputc(&obuf, lineno>>8);
-	Bputc(&obuf, lineno>>16);
-	Bputc(&obuf, lineno>>24);
+	Bputc(&obuf, stmtline);
+	Bputc(&obuf, stmtline>>8);
+	Bputc(&obuf, stmtline>>16);
+	Bputc(&obuf, stmtline>>24);
 	zaddr(&g2->from, sf);
 	zaddr(&g2->to, st);
 

src/cmd/ld/dwarf.c

@@ -436,7 +436,7 @@ decodez(char *s)
  * The line history itself
  */
 
-static char **histfile;	   // [0] holds the empty string.
+static char **histfile;	   // [0] holds "<eof>", DW_LNS_set_file arguments must be > 0.
 static int  histfilesize;
 static int  histfilecap;
 
@@ -445,7 +445,7 @@ clearhistfile(void)
 {
 	int i;
 
-	// [0] holds the empty string.
+	// [0] holds "<eof>"
 	for (i = 1; i < histfilesize; i++)
 		free(histfile[i]);
 	histfilesize = 0;
@@ -762,6 +762,11 @@ writelines(void)
 				diag("corrupt history or bad absolute line: %P", q);
 				continue;
 			}
+			if (lh->file < 1) {  // 0 is the past-EOF entry.
+				diag("instruction with linenumber past EOF in %s: %P", unitname, q);
+				continue;
+			}
+
 			lline = lh->line + q->line - lh->absline;
 			if (debug['v'] > 1)
 				print("%6llux %s[%lld] %P\n", q->pc, histfile[lh->file], lline, q);