Made csa and csb work with mcg; adjust the libem functions and the

corresponding invocation in the ncg table so the same helpers can be used for
both mcg and ncg. Add a new IR opcode, FARJUMP, which jumps to a helper
function but saves volatile registers.

mach/powerpc/libem/csa.s

@@ -12,11 +12,14 @@
 ! address and jumps to it.
 ! traps if resulting address is zero
 !
-! On entry: r3 = address of CSA table
+! Stack: ( value tableaddr -- )
-!           r4 = value
 
 .define .csa
 .csa:
+	lwz r3, 0(sp)
+	lwz r4, 4(sp)
+	addi sp, sp, 8
+
 	lwz r5, 0(r3)            ! load default
 	mtspr ctr, r5
 	

mach/powerpc/libem/csb.s

@@ -12,11 +12,14 @@
 ! address and jumps to it.
 ! traps if resulting address is zero
 !
-! On entry: r3 = address of CSB table
+! Stack: ( value tableaddr -- )
-!           r4 = value
 
 .define .csb
 .csb:
+	lwz r3, 0(sp)
+	lwz r4, 4(sp)
+	addi sp, sp, 8
+
 	lwz r5, 0(r3)            ! load default
 	mtspr ctr, r5
 	

mach/powerpc/mcg/table

@@ -466,6 +466,11 @@ PATTERNS
 		emit "b $addr"
 		cost 4;
 
+	FARJUMP(addr:LABEL.I)
+        with corrupted(volatile)
+		emit "b $addr"
+		cost 4;
+
     JUMP(dest:(int)reg)
         emit "mtspr ctr, %dest"
         emit "bcctrl 20, 0, 0"

mach/powerpc/ncg/table

@@ -1898,12 +1898,12 @@ PATTERNS
 				addi SP, SP, {CONST, 12}
 				
 	pat csa                            /* Array-lookup switch */
-		with GPR3 GPR4 STACK
+		with STACK
 			gen
 				b {LABEL, ".csa"}
 				
 	pat csb                            /* Table-lookup switch */
-		with GPR3 GPR4 STACK
+		with STACK
 			gen
 				b {LABEL, ".csb"}
 

mach/proto/mcg/treebuilder.c

@@ -1130,9 +1130,8 @@ static void insn_ivalue(int opcode, arith value)
         case op_csa:
         case op_csb:
         {
-            const char* helper = aprintf(".%s%d",
+            const char* helper = aprintf(".%s",
-                (opcode == op_csa) ? "csa" : "csb",
+                (opcode == op_csa) ? "csa" : "csb");
-                value);
             struct ir* descriptor = pop(EM_pointersize);
 
             if (descriptor->opcode != IR_LABEL)
@@ -1143,7 +1142,7 @@ static void insn_ivalue(int opcode, arith value)
             materialise_stack();
             appendir(
                 new_ir2(
-                    IR_JUMP, 0,
+                    IR_FARJUMP, 0,
                     new_labelir(helper),
                     extract_block_refs(bb_get(descriptor->u.lvalue))
                 )

plat/qemuppc/descr

@@ -33,8 +33,7 @@ var C_INCLUDES=-I{PLATFORMDIR}/include -I{EM}/share/ack/include/ansi
 name be
 	from .m.g
 	to .s
-	# Change this back to ncg to revert to the old code generator
+	program {EM}/lib/ack/{PLATFORM}/mcg
-	program {EM}/lib/ack/{PLATFORM}/ncg
 	mapflag -gdb GF=-gdb
 	args {GF?} <
 	stdout

plat/qemuppc/tests/_dummy.c

@@ -5,4 +5,4 @@ void _m_a_i_n(void)
 {
     ASSERT(0 == 0);
     finished();
-}
+}

plat/qemuppc/tests/csa_e.c

@@ -0,0 +1,26 @@
+#include "test.h"
+
+int csa(int i)
+{
+    switch (i)
+    {
+        case 2:  return 2;
+        case 3:  return 3;
+        case 4:  return 4;
+        default: return 0;
+    }
+}
+
+/* Bypasses the CRT, so there's no stdio or BSS initialisation. */
+void _m_a_i_n(void)
+{
+    ASSERT(csa(0) == 0);
+    ASSERT(csa(1) == 0);
+    ASSERT(csa(2) == 2);
+    ASSERT(csa(3) == 3);
+    ASSERT(csa(4) == 4);
+    ASSERT(csa(5) == 0);
+    ASSERT(csa(6) == 0);
+
+    finished();
+}

plat/qemuppc/tests/csb_e.c

@@ -0,0 +1,26 @@
+#include "test.h"
+
+int csa(int i)
+{
+    switch (i)
+    {
+        case 200:  return 200;
+        case 300:  return 300;
+        case 400:  return 400;
+        default: return 0;
+    }
+}
+
+/* Bypasses the CRT, so there's no stdio or BSS initialisation. */
+void _m_a_i_n(void)
+{
+    ASSERT(csa(0) == 0);
+    ASSERT(csa(100) == 0);
+    ASSERT(csa(200) == 200);
+    ASSERT(csa(300) == 300);
+    ASSERT(csa(400) == 400);
+    ASSERT(csa(500) == 0);
+    ASSERT(csa(600) == 0);
+
+    finished();
+}

util/mcgg/ir.dat

@@ -103,6 +103,7 @@ S ?=i. SETRET
 
 # Flow control --- these never return
 V .=i. JUMP
+V .=i. FARJUMP
 V .=i. CJUMPEQ
 V .=i. CJUMPLT
 V .=i. CJUMPLE