X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fincludes%2FTailCalls.h;h=670da9546f75de9df447311bef7f9edbfd293f0e;hb=e6218fe7eff4e34e1a3c823cd4b7aebe09d2d4fb;hp=92d4f72c6b8b71263057160e2a9b677ffd982f74;hpb=4d69b633a31eb2b19141c984ffbe448b74bb5885;p=ghc-hetmet.git

diff --git a/ghc/includes/TailCalls.h b/ghc/includes/TailCalls.h
index 92d4f72..670da95 100644
--- a/ghc/includes/TailCalls.h
+++ b/ghc/includes/TailCalls.h
@@ -1,5 +1,4 @@
 /* -----------------------------------------------------------------------------
- * $Id: TailCalls.h,v 1.8 2002/03/26 10:30:44 simonmar Exp $
  *
  * (c) The GHC Team, 1998-1999
  *
@@ -16,7 +15,7 @@
 
 #ifdef USE_MINIINTERPRETER
 
-#define JMP_(cont) return(stgCast(StgFunPtr,cont))
+#define JMP_(cont) return((StgFunPtr)(cont))
 #define FB_
 #define FE_
 
@@ -28,7 +27,7 @@ extern void __DISCARD__(void);
    Tail calling on x86
    -------------------------------------------------------------------------- */
 
-#if i386_TARGET_ARCH
+#if i386_HOST_ARCH
 
 /* Note about discard: possibly there to fool GCC into clearing up
    before we do the jump eg. if there are some arguments left on the C
@@ -51,19 +50,54 @@ extern void __DISCARD__(void);
 
 #define JMP_(cont)			\
     { 					\
-      void *target;			\
+      void *__target;			\
       __DISCARD__();			\
-      target = (void *)(cont);    	\
-      goto *target; 	    	    	\
+      __target = (void *)(cont);    	\
+      goto *__target; 	    	    	\
+    }
+
+#endif /* i386_HOST_ARCH */
+
+/* -----------------------------------------------------------------------------
+   Tail calling on x86_64
+   -------------------------------------------------------------------------- */
+
+#if x86_64_HOST_ARCH
+
+/*
+  NOTE about __DISCARD__():
+
+  On x86_64 this is necessary to work around bugs in the register
+  variable support in gcc.  Without the __DISCARD__() call, gcc will
+  silently throw away assignements to global register variables that
+  happen before the jump.
+
+  Here's the example:
+
+  extern void g(void);
+  static void f(void) {
+    R1 = g;
+    __DISCARD__()
+    goto *R1;
+  }
+
+  without the dummy function call, gcc throws away the assignment to R1
+  (gcc 3.4.3) gcc bug #20359.
+*/
+
+#define JMP_(cont)			\
+    { 					\
+      __DISCARD__();			\
+      goto *(void *)(cont); 	    	    	\
     }
 
-#endif /* i386_TARGET_ARCH */
+#endif /* x86_64_HOST_ARCH */
 
 /* -----------------------------------------------------------------------------
    Tail calling on Sparc
    -------------------------------------------------------------------------- */
 
-#ifdef sparc_TARGET_ARCH
+#ifdef sparc_HOST_ARCH
 
 #define JMP_(cont)	((F_) (cont))()
 	/* Oh so happily, the above turns into a "call" instruction,
@@ -75,26 +109,29 @@ extern void __DISCARD__(void);
 #define FB_
 #define FE_
 
-#endif /* sparc_TARGET_ARCH */
+#endif /* sparc_HOST_ARCH */
 
 /* -----------------------------------------------------------------------------
    Tail calling on Alpha
    -------------------------------------------------------------------------- */
 
-#ifdef alpha_TARGET_ARCH
+#ifdef alpha_HOST_ARCH
 
+#if IN_STG_CODE
 register void *_procedure __asm__("$27");
+#endif
 
-#define JMP_(cont)	    	    	    	\
-    do { _procedure = (void *)(cont);    	\
-         goto *_procedure;    	    	    	\
+#define JMP_(cont)				\
+    do { _procedure = (void *)(cont);		\
+         __DISCARD__();				\
+         goto *_procedure;			\
        } while(0)
 
 /* Don't need these for alpha mangling */
 #define FB_
 #define FE_
 
-#endif /* alpha_TARGET_ARCH */
+#endif /* alpha_HOST_ARCH */
 
 /* -----------------------------------------------------------------------------
    Tail calling on HP
@@ -155,25 +192,54 @@ but uses $$dyncall if necessary to cope, just in case you aren't.
    Tail calling on PowerPC
    -------------------------------------------------------------------------- */
 
-#ifdef powerpc_TARGET_ARCH
+#ifdef powerpc_HOST_ARCH
 
 #define JMP_(cont)			\
     { 					\
       void *target;			\
       target = (void *)(cont);    	\
+      __DISCARD__();			\
       goto *target; 	    	    	\
     }
 
 /*
+	The __DISCARD__ is there because Apple's April 2002 Beta of GCC 3.1
+	sometimes generates incorrect code otherwise.
+	It tends to "forget" to update global register variables in the presence
+	of decrement/increment operators:
+	JMP_(*(--Sp)) is wrongly compiled as JMP_(Sp[-1]).
+	Calling __DISCARD__ in between works around this problem.
+*/
+
+/*
 	I would _love_ to use the following instead,
-	but GCC fails to generate code for it if it is called for a casted
-	data pointer - which is exactly what we are going to do...
+	but some versions of Apple's GCC fail to generate code for it
+	if it is called for a casted data pointer - which is exactly what
+	we are going to do...
 
 	#define JMP_(cont)	((F_) (cont))()
 */
 
+#endif /* powerpc_HOST_ARCH */
 
-#endif /* sparc_TARGET_ARCH */
+#ifdef powerpc64_HOST_ARCH
+#define JMP_(cont) ((F_) (cont))()
+#endif
+
+/* -----------------------------------------------------------------------------
+   Tail calling on IA64
+   -------------------------------------------------------------------------- */
+
+#ifdef ia64_HOST_ARCH
+
+/* The compiler can more intelligently decide how to do this.  We therefore
+ * implement it as a call and optimise to a jump at mangle time. */
+#define JMP_(cont)	((F_) (cont))(); __asm__ volatile ("--- TAILCALL ---");
+
+/* Don't emit calls to __DISCARD__ as this causes hassles */
+#define __DISCARD__()
+
+#endif
 
 /* -----------------------------------------------------------------------------
   FUNBEGIN and FUNEND.