From 1c06515d927d9de1582438d4eb5953890e79c5c7 Mon Sep 17 00:00:00 2001
From: Alan Modra <amodra@gmail.com>
Date: Sat, 16 Nov 2013 06:41:36 -0500
Subject: [PATCH] The powerpc64 ABIs align structs passed by value, a fact
 ignored by gcc for quite some time.  Since gcc now does the correct
 alignment, libffi needs to follow suit.  This ought to be made selectable via
 a new abi value, and the #ifdefs removed from ffi.c along with many other
 #ifdefs present there and in assembly.  I'll do that with a followup patch
 sometime.

This is a revised version of
https://sourceware.org/ml/libffi-discuss/2013/msg00162.html
---
 ChangeLog         |  7 +++++++
 src/powerpc/ffi.c | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index bca12119..2a4c8dc8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2013-11-16  Alan Modra  <amodra@gmail.com>
+
+	* src/powerpc/ffi.c (ffi_prep_args64): Align struct parameters
+	according to __STRUCT_PARM_ALIGN__.
+	(ffi_prep_cif_machdep_core): Likewise.
+	(ffi_closure_helper_LINUX64): Likewise.
+
 2013-11-16  Alan Modra  <amodra@gmail.com>
 
 	* src/powerpc/linux64.S (ffi_call_LINUX64): Tweak restore of r28.
diff --git a/src/powerpc/ffi.c b/src/powerpc/ffi.c
index a22ac27b..12501b6d 100644
--- a/src/powerpc/ffi.c
+++ b/src/powerpc/ffi.c
@@ -439,6 +439,7 @@ ffi_prep_args64 (extended_cif *ecif, unsigned long *const stack)
     unsigned long *ul;
     float *f;
     double *d;
+    size_t p;
   } valp;
 
   /* 'stacktop' points at the previous backchain pointer.  */
@@ -473,6 +474,9 @@ ffi_prep_args64 (extended_cif *ecif, unsigned long *const stack)
     double **d;
   } p_argv;
   unsigned long gprvalue;
+#ifdef __STRUCT_PARM_ALIGN__
+  unsigned long align;
+#endif
 
   stacktop.c = (char *) stack + bytes;
   gpr_base.ul = stacktop.ul - ASM_NEEDS_REGISTERS64 - NUM_GPR_ARG_REGISTERS64;
@@ -549,6 +553,13 @@ ffi_prep_args64 (extended_cif *ecif, unsigned long *const stack)
 #endif
 
 	case FFI_TYPE_STRUCT:
+#ifdef __STRUCT_PARM_ALIGN__
+	  align = (*ptr)->alignment;
+	  if (align > __STRUCT_PARM_ALIGN__)
+	    align = __STRUCT_PARM_ALIGN__;
+	  if (align > 1)
+	    next_arg.p = ALIGN (next_arg.p, align);
+#endif
 	  words = ((*ptr)->size + 7) / 8;
 	  if (next_arg.ul >= gpr_base.ul && next_arg.ul + words > gpr_end.ul)
 	    {
@@ -853,6 +864,10 @@ ffi_prep_cif_machdep_core (ffi_cif *cif)
   else
     for (ptr = cif->arg_types, i = cif->nargs; i > 0; i--, ptr++)
       {
+#ifdef __STRUCT_PARM_ALIGN__
+	unsigned int align;
+#endif
+
 	switch ((*ptr)->type)
 	  {
 #if FFI_TYPE_LONGDOUBLE != FFI_TYPE_DOUBLE
@@ -868,6 +883,14 @@ ffi_prep_cif_machdep_core (ffi_cif *cif)
 	    break;
 
 	  case FFI_TYPE_STRUCT:
+#ifdef __STRUCT_PARM_ALIGN__
+	    align = (*ptr)->alignment;
+	    if (align > __STRUCT_PARM_ALIGN__)
+	      align = __STRUCT_PARM_ALIGN__;
+	    align = align / 8;
+	    if (align > 1)
+	      intarg_count = ALIGN (intarg_count, align);
+#endif
 	    intarg_count += ((*ptr)->size + 7) / 8;
 	    break;
 
@@ -1399,6 +1422,9 @@ ffi_closure_helper_LINUX64 (ffi_closure *closure, void *rvalue,
   unsigned long i, avn, nfixedargs;
   ffi_cif *cif;
   ffi_dblfl *end_pfr = pfr + NUM_FPR_ARG_REGISTERS64;
+#ifdef __STRUCT_PARM_ALIGN__
+  unsigned long align;
+#endif
 
   cif = closure->cif;
   avalue = alloca (cif->nargs * sizeof (void *));
@@ -1453,6 +1479,13 @@ ffi_closure_helper_LINUX64 (ffi_closure *closure, void *rvalue,
 	  break;
 
 	case FFI_TYPE_STRUCT:
+#ifdef __STRUCT_PARM_ALIGN__
+	  align = arg_types[i]->alignment;
+	  if (align > __STRUCT_PARM_ALIGN__)
+	    align = __STRUCT_PARM_ALIGN__;
+	  if (align > 1)
+	    pst = (unsigned long *) ALIGN ((size_t) pst, align);
+#endif
 #ifndef __LITTLE_ENDIAN__
 	  /* Structures with size less than eight bytes are passed
 	     left-padded.  */