Allow sp and fp on the fake stack.

This simplifies parts of the PowerPC table and causes ncg to better
decide whether to push sp or fp to the real stack, or coerce it to
REG3, or coerce it to REG-REG3, or move it to a regvar.  These better
decisions remove extra _mr_ instructions.

The idea comes from mach/powerpc/arm/table, where SP has a property
STACKPOINTER and LB has LOCALBASE.  I don't need two properties, so I
make one property SPFP for both registers.

mach/powerpc/ncg/table

@@ -31,6 +31,7 @@ PC_OFFSET = 4   /* Offset of saved PC relative to our FP */
 PROPERTIES
 
 	GPR             /* general-purpose register */
+	SPFP            /* sp or fp */
 	REG             /* allocatable GPR */
 	REG3            /* coercion to r3 */
 
@@ -51,7 +52,8 @@ REGISTERS
 	 *   r13, r14, ..., r31: GPR, REG regvar(reg_any).
 	 */
 
-	r0, sp, fp, r12                   : GPR.
+	r0, r12                           : GPR.
+	sp, fp                            : GPR, SPFP.
 	r3                                : GPR, REG, REG3.
 	r4, r5, r6, r7, r8, r9, r10, r11  : GPR, REG.
 
@@ -238,7 +240,7 @@ SETS
 	MEMORY          = IND_V + FRAME_V.
 
 	/* any integer from stack that we can easily move to GPR */
-	INT_W   = REG + CONST_STACK + SEX_B + SEX_H +
+	INT_W   = SPFP + REG + CONST_STACK + SEX_B + SEX_H +
 	          SUM_RIS + SUM_RC + SUM_RL + SUM_RR +
 	          SUB_RR + NEG_R + MUL_RR + DIV_RR + DIV_RR_U +
 	          IND_ALL_B + IND_ALL_H + IND_ALL_W +
@@ -717,19 +719,14 @@ TESTS
 
 STACKINGRULES
 
-	/* We don't allow GPR-REG on the stack.  The intent is to ban
+	from SPFP+REG to STACK
-	 * r0 from the stack, but this also bans fp from the stack.
-	 * This is odd because most other tables for ncg allow the
-	 * frame pointer on the stack.
-	 */
-	from REG to STACK
 		gen
-			COMMENT("stack REG")
+			COMMENT("stack SPFP+REG")
 			stwu %1, {IND_RC_W, sp, 0-4}
 
-	from INT_W-REG to STACK
+	from INT_W-SPFP-REG to STACK
 		gen
-			COMMENT("stack INT_W-REG")
+			COMMENT("stack INT_W-SPFP-REG")
 			move %1, RSCRATCH
 			stwu RSCRATCH, {IND_RC_W, sp, 0-4}
 
@@ -1146,26 +1143,15 @@ PATTERNS
 			uses REG={LXFRAME, $1}
 			gen move %1, {FRAME_D, $1, %a, $2, 8}
 
-	/* Programs use "lxl cal" to pass the static chain and call a
+	pat lxl nicelx($1)                 /* Local base on static chain */
-	 * nested procedure.  This must push a token LXFRAME or the
-	 * register fp to the real stack. */
-
-	/* Local base of procedure on static chain */
-	pat lxl nicelx($1)
 		uses REG={LXFRAME, $1}
 		yields %a  /* Can't yield LXFRAME. */
 	pat lxl stl nicelx($1) && inreg($2)==reg_any
 		kills regvar($2)
 		gen move {LXFRAME, $1}, {REG_EXPR, regvar($2)}
 
-	pat lxl cal $1==0  /* Pass our local base to procedure */
-		with STACK
-			gen stwu fp, {IND_RC_W, sp, 0-4}
-			leaving cal $2
-
 	pat lxl $1==0                      /* Our local base */
-		uses REG=fp
+		yields fp
-		yields %a  /* Can't yield fp. */
 
 	pat lxa $1==0                      /* Our argument base */
 		yields {SUM_RC, fp, EM_BSIZE}
@@ -2134,7 +2120,8 @@ PATTERNS
 			bls
 
 	pat bls                            /* Block move variable length */
-		with REG REG REG
+		with REG SPFP+REG SPFP+REG
+			/* allows sp as %2, %3 */
 			/* ( src%3 dst%2 len%1 -- ) */
 			uses reusing %1, REG, REG, REG
 			gen
@@ -2230,22 +2217,14 @@ PATTERNS
 
 	pat lor $1==1                      /* Load stack pointer */
 		with STACK
-			uses REG=sp
+			yields sp
-			yields %a  /* Can't yield sp. */
 
 	/* Next few patterns for "lor 1" appear in
 	 * lang/m2/libm2/par_misc.e
 	 */
-	pat lor lor $1==1 && $2==1         /* Load sp twice */
-		with STACK
-			gen stwu sp, {IND_RC_W, sp, 0-4}
-			leaving lor 1
-
 	pat lor adp $1==1 && smalls($2)    /* sp + constant */
 		with STACK
-			uses REG
+			yields {SUM_RC, sp, $2}
-			gen addi %a, sp, {C, $2}
-			yields %a
 
 	/* Subtract stack pointer by doing %1 - (sp - 4)
 	 * because sp - 4 would point to %1.