20020118-1.c: New.

2002-01-18  Aldy Hernandez  <aldyh@redhat.com>

        * gcc.dg/20020118-1.c: New.

        * tm.texi (STARTING_FRAME_PHASE): Document.

        * function.c (assign_stack_local_1): Adjust x_frame_offset with
        STARTING_FRAME_PHASE.
        (STARTING_FRAME_PHASE): New.
        (instantiate_virtual_regs): Check saneness of
        STARTING_FRAME_PHASE.

        * rs6000.h (STARTING_FRAME_PHASE): New.

From-SVN: r49006

4 files changed, 50 insertions, 2 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 8601b2d..20612cc 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,15 @@
+2002-01-18  Aldy Hernandez  <aldyh@redhat.com>
+
+        * doc/tm.texi (STARTING_FRAME_PHASE): Document.
+
+        * function.c (assign_stack_local_1): Adjust x_frame_offset with
+        STARTING_FRAME_PHASE.
+        (STARTING_FRAME_PHASE): New.
+        (instantiate_virtual_regs): Check saneness of
+        STARTING_FRAME_PHASE.
+
+        * config/rs6000/rs6000.h (STARTING_FRAME_PHASE): New.
+
 2002-01-19  Alexandre Oliva  <aoliva@redhat.com>
 
 	* config/sh/sh.md (movdf_i4 split): Fix alter_subreg calls.
diff --git a/gcc/config/rs6000/rs6000.h b/gcc/config/rs6000/rs6000.h
index 589dc9d..d00b7ed 100644
--- a/gcc/config/rs6000/rs6000.h
+++ b/gcc/config/rs6000/rs6000.h
@@ -1399,6 +1399,11 @@ typedef struct rs6000_stack {
    + RS6000_VARARGS_AREA						\
    + RS6000_SAVE_AREA)
 
+/* How far (in bytes) is the start of the frame from the stack
+   alignment.  For ppc 32bits, the stack is aligned to 128 bits, but
+   the frame starts 64bits later.  */
+#define STARTING_FRAME_PHASE (TARGET_32BIT ? 8 : 0)
+
 /* Offset from the stack pointer register to an item dynamically
    allocated on the stack, e.g., by `alloca'.
 
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index c81461d..bb296ee 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -2598,6 +2598,18 @@ value @code{STARTING_FRAME_OFFSET}.
 @c i'm not sure if the above is still correct.. had to change it to get
 @c rid of an overfull.  --mew 2feb93
 
+@findex STARTING_FRAME_PHASE
+@item STARTING_FRAME_PHASE
+This option species how many bytes the frame is out of phase from the
+stack alignment.
+
+For example, some ports assume a stack alignment of 128 bits, but the
+start of the frame is 64 bits displaced from this alignment.  In this
+case, you would define @code{STARTING_FRAME_PHASE} to be 8.
+
+This macro defaults to 0, so there is no need to define it if the start
+of the frame maintains the stack alignment.
+
 @findex STACK_POINTER_OFFSET
 @item STACK_POINTER_OFFSET
 Offset from the stack pointer register to the first location at which
diff --git a/gcc/function.c b/gcc/function.c
index 4cff6bb..cd39757 100644
--- a/gcc/function.c
+++ b/gcc/function.c
@@ -68,6 +68,10 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 #define LOCAL_ALIGNMENT(TYPE, ALIGNMENT) ALIGNMENT
 #endif
 
+#ifndef STARTING_FRAME_PHASE
+#define STARTING_FRAME_PHASE 0
+#endif
+
 /* Some systems use __main in a way incompatible with its use in gcc, in these
    cases use the macros NAME__MAIN to give a quoted symbol and SYMBOL__MAIN to
    give the same symbol without quotes for an alternative entry point.  You
@@ -567,9 +571,9 @@ assign_stack_local_1 (mode, size, align, function)
      like.  So we instead assume that ALIGNMENT is a power of two and
      use logical operations which are unambiguous.  */
 #ifdef FRAME_GROWS_DOWNWARD
-  function->x_frame_offset = FLOOR_ROUND (function->x_frame_offset, alignment);
+  function->x_frame_offset = FLOOR_ROUND (function->x_frame_offset - STARTING_FRAME_PHASE, alignment) + STARTING_FRAME_PHASE;
 #else
-  function->x_frame_offset = CEIL_ROUND (function->x_frame_offset, alignment);
+  function->x_frame_offset = CEIL_ROUND (function->x_frame_offset - STARTING_FRAME_PHASE, alignment) + STARTING_FRAME_PHASE;
 #endif
 
   /* On a big-endian machine, if we are allocating more space than we will use,
@@ -3477,6 +3481,21 @@ instantiate_virtual_regs (fndecl, insns)
   rtx insn;
   unsigned int i;
 
+  if (STARTING_FRAME_PHASE > 0)
+    {
+      /* Make sure the frame offset and phase displacement are aligned as
+	 advertised.
+
+	 Only do the sanity check if we have a STARTING_FRAME_PHASE,
+	 else we might trigger this abort on ports who claim to have
+	 STARTING_FRAME_OFFSET aligned properly, but don't.  I suppose
+	 we could enable this and fix those ports.  */
+
+      if ((STARTING_FRAME_OFFSET + STARTING_FRAME_PHASE)
+	  % (STACK_BOUNDARY / BITS_PER_UNIT))
+	abort ();
+    }
+
   /* Compute the offsets to use for this function.  */
   in_arg_offset = FIRST_PARM_OFFSET (fndecl);
   var_offset = STARTING_FRAME_OFFSET;