compiling a prologue and epilogue on PowerPC

library/compiler/linearizer.factor

@@ -31,6 +31,12 @@ SYMBOL: #target ( part of jump table )
 SYMBOL: #target-label
 SYMBOL: #end-dispatch
 
+! on PowerPC, compiled definitions that make subroutine calls
+! must have a prologue and epilogue to set up and tear down the
+! link register.
+SYMBOL: #prologue
+SYMBOL: #epilogue
+
 : linear, ( node -- )
     #! Add a node to the linear IR.
     [ node-op get node-param get ] bind cons , ;
@@ -50,7 +56,7 @@ SYMBOL: #end-dispatch
     #! jumps and labels, and turns dataflow IR nodes into
     #! lists where the first element is an operation, and the
     #! rest is arguments.
-    [ (linearize) ] make-list ;
+    [ [ #prologue ] , (linearize) ] make-list ;
 
 : immediate? ( obj -- ? )
     #! fixnums and f have a pointerless representation, and
@@ -83,6 +89,8 @@ SYMBOL: #end-dispatch
     linearize-simple-label
 ] "linearizer" set-word-prop
 
+: return,  [ #epilogue ] ,  [ #return ] , ;
+
 : linearize-label ( node -- )
     #! Labels are tricky, because they might contain non-tail
     #! calls. So we push the address of the location right after
@@ -92,7 +100,7 @@ SYMBOL: #end-dispatch
     #! not contain non-tail recursive calls to itself.
     <label> dup #return-to swons , >r
     linearize-simple-label
-    [ #return ] ,
+    return,
     r> label, ;
 
 #label [
@@ -136,3 +144,5 @@ SYMBOL: #end-dispatch
 ] "linearizer" set-word-prop
 
 #values [ drop ] "linearizer" set-word-prop
+
+#return [ drop return, ] "linearizer" set-word-prop

library/compiler/ppc/generator.factor

@@ -3,4 +3,23 @@
 IN: compiler
 USING: assembler inference kernel words ;
 
+! At the start of each word that calls a subroutine, we store
+! the link register in r0, then push r0 on the C stack.
+#prologue [
+    drop
+    0 MFLR
+    0 1 -4 STWU
+] "generator" set-word-prop
+
+! At the end of each word that calls a subroutine, we store
+! the previous link register value in r0 by popping it off the
+! stack, set the link register to the contents of r0, and jump
+! to the link register.
+#epilogue [
+    drop
+    0 1 0 LWZ
+    1 1 4 ADDI
+    0 MTLR
+] "generator" set-word-prop
+
 #return [ drop BLR ] "generator" set-word-prop

library/compiler/simplifier.factor

@@ -92,6 +92,8 @@ SYMBOL: simplifying
     car cdr find-label cdr
 ] "next-logical" set-word-prop
 
+#epilogue [ cdr ] "next-logical" set-word-prop
+
 : next-logical? ( op linear -- ? )
     next-logical dup [ car car = ] [ 2drop f ] ifte ;
 

library/compiler/x86/generator.factor

@@ -4,6 +4,10 @@ IN: compiler
 USING: alien assembler inference kernel kernel-internals lists
 math memory namespaces words ;
 
+! Not used on x86
+#prologue [ drop ] "generator" set-word-prop
+#epilogue [ drop ] "generator" set-word-prop
+
 \ slot [
     PEEK-DS
     2unlist type-tag >r cell * r> - EAX swap 2list EAX swap MOV