Remove stackadjust and stackoffset() from ncg.

This feature has never been used since its introduction, more than 3
years ago, in David Given's commit c93cb69 of May 8, 2013.  The commit
was for "PowerPC and M68K work".  I am not undoing the entire commit.
I am only removing the stackadjust and stackoffset() feature.

This commit removes the feature from my branch kernigh-linuxppc.  This
removal includes the mach/proto/ncg parts.  The default branch already
removed most of the feature, but kept the mach/proto/ncg parts.  That
removal happened in commit 81778b6 of May 13, 2013 (which was a merge;
git diff af0dede 81778b6).  The branch dtrg-experimental-powerpc
merged the default branch but without the removal.  That merge was
commit 4703db0f of Sep 15, 2016 (git diff 8c94b13 4703db0).  My branch
kernigh-linuxppc is off branch dtrg-experimental-powerpc, so I can no
longer get the removal by merging default.

David Given described the stackadjust feature in
  https://sourceforge.net/p/tack/mailman/message/30814691/

The instruction stackadjust would add a value to the offset, and the
function stackoffset() would return this offset.  One would use this
to track sp - fp, then omit the frame pointer by not keeping fp in a
register.

h/cgg_cg.h

@@ -39,7 +39,6 @@
 #define DO_TOSTACK	23
 #define DO_KILLREG	24
 #define DO_LABDEF	25
-#define DO_STACKADJUST	26
 
 #ifndef MAXATT
 #define MAXATT TOKENSIZE
@@ -134,7 +133,6 @@ typedef struct exprnode *node_p;
 #define EX_ISROM	44
 #define EX_TOPELTSIZE	45
 #define EX_FALLTHROUGH	46
-#define EX_STACKOFFSET	47
 
 
 typedef struct {        /* to stack coercions */

mach/proto/ncg/codegen.c

@@ -909,23 +909,6 @@ normalfailed:	if (stackpad!=tokpatlen) {
 
 	break;
     }
-#endif
-#ifdef USE_NOFRAMEPOINTER
-	case DO_STACKADJUST: {
-	result_t result;
-	int nodeno;
-	
-	DEBUG("STACKADJUST");
-	/* The offset is an expression, which we need to evaluate. */
-	
-	getint(nodeno,codep);
-	compute(&enodes[nodeno], &result);
-	assert(result.e_typ==EV_INT);
-	
-	if (toplevel)
-		stackoffset += result.e_v.e_con;
-	break;
-	}
 #endif
 	}
 	}

mach/proto/ncg/extern.h

@@ -20,9 +20,6 @@ extern rl_p curreglist;                 /* side effect of findcoerc() */
 #ifndef NDEBUG
 extern int Debug;                       /* on/off debug printout */
 #endif
-#ifdef USE_NOFRAMEPOINTER
-extern int stackoffset;                 /* offset from localbase to sp */
-#endif
 
 /*
  * Next descriptions are external declarations for tables created

util/ncgg/cgg.y

@@ -38,7 +38,7 @@ int Xstackflag=0; /* set in coercions, moves, and tests. %1 means something
 		   */
 
 struct varinfo *gen_inst(),*gen_move(),*gen_test(),*gen_preturn(),*gen_tlab();
-struct varinfo *gen_label(), *gen_stackadjust(), *make_erase();
+struct varinfo *gen_label(), *make_erase();
 expr_t make_expr(),ident_expr(),subreg_expr(),tokm_expr(),all_expr();
 expr_t perc_ident_expr(),sum_expr(),regvar_expr();
 
@@ -74,9 +74,9 @@ iocc_t iops[20];
 %token TOPELTSIZE FALLTHROUGH LABELDEF
 %token PROC CALL EXAMPLE
 %token FROM TO
-%token TEST MOVE STACK RETURN STACKADJUST
+%token TEST MOVE STACK RETURN
 %token PATTERNS PAT WITH EXACT KILLS USES REUSING GEN YIELDS LEAVING
-%token DEFINED SAMESIGN SFIT UFIT ROM LOWW HIGHW ISROM STACKOFFSET
+%token DEFINED SAMESIGN SFIT UFIT ROM LOWW HIGHW ISROM
 %token CMPEQ CMPNE CMPLT CMPGT CMPLE CMPGE OR2 AND2 LSHIFT RSHIFT NOT COMP
 %token INREG REGVAR REG_ANY REG_FLOAT REG_LOOP REG_POINTER
 %token <yy_int> ADORNACCESS
@@ -849,8 +849,6 @@ gen_instruction
 		{ $$ = gen_label($2-1); use_tes++; }
 	| RETURN
 		{ $$ = gen_preturn(); }
-	| STACKADJUST expr
-		{ $$ = gen_stackadjust($2.ex_index); use_noframepointer++; }
 	;
 optstar
 	: /* empty */
@@ -1030,8 +1028,6 @@ expr
 		{ $$ = make_expr(TYPINT,EX_LOWW,$3-1,0); }
 	| HIGHW '(' emarg ')'
 		{ $$ = make_expr(TYPINT,EX_HIGHW,$3-1,0); }
-	| STACKOFFSET '(' ')'
-		{ $$ = make_expr(TYPINT,EX_STACKOFFSET, 0, 0); }
 /* Excluded, because it causes a shift-reduce conflict
    (problems with a tokenset_no followed by an optexpr)
 	| '-' expr %prec UMINUS

util/ncgg/coerc.c

@@ -127,15 +127,6 @@ struct varinfo *gen_preturn() {
 	return(vp);
 }
 
-struct varinfo *gen_stackadjust(int expr) {
-	register struct varinfo *vp;
-
-	NEW(vp,struct varinfo);
-	vp->vi_int[0] = INSSTACKADJUST;
-	vp->vi_int[1] = expr;
-	return(vp);
-}
-
 struct varinfo *gen_tlab(n) {
 	register struct varinfo *vp;
 

util/ncgg/extern.h

@@ -37,7 +37,6 @@ extern int regclass;
 extern int maxtokensize;
 extern int nprocargs, maxprocargs;
 extern int use_tes;
-extern int use_noframepointer;
 
 extern char *mystrcpy();
 extern char *myalloc();

util/ncgg/keywords

@@ -43,8 +43,6 @@ reusing	REUSING
 rom	ROM
 samesign	SAMESIGN
 sfit	SFIT
-stackadjust STACKADJUST
-stackoffset STACKOFFSET
 topeltsize	TOPELTSIZE
 test	TEST
 to	TO

util/ncgg/output.c

@@ -12,8 +12,6 @@ int	tabledebug=0;	/* do not generate code for table debugging */
 #endif
 int	verbose=0;	/* print all statistics */
 int	use_tes;	/* use top element size information */
-int use_noframepointer;	/* use stackadjust mechanism to remove requirement
-                           for frame pointer */
 char	*c_file=	"tables.c";
 char	*h_file=	"tables.H";
 char	*cd_file=	"code";
@@ -614,8 +612,6 @@ outdefs() {
 		cdef("TABLEDEBUG",1);
 	if (use_tes)
 		cdef("USE_TES",1);
-	if (use_noframepointer)
-		cdef("USE_NOFRAMEPOINTER",1);
 }
 
 outars() {
@@ -856,11 +852,6 @@ varinfo *kills,*allocates,*generates,*yields,*leaving;
 			codeint(vp->vi_int[1]);
 			codenl();
 			break;
-		case INSSTACKADJUST:
-			code8(DO_STACKADJUST);
-			codeint(vp->vi_int[1]);
-			codenl();
-			break;
 		}
 	}
 	codecoco(cocono);

util/ncgg/pseudo.h

@@ -12,4 +12,3 @@
 #define INSERASE	(-6)
 #define INSREMOVE	(-7)
 #define INSLABDEF	(-8)
-#define INSSTACKADJUST (-9)