[PATCH] rs6000: Small varargs for BE SVR4 (PR61729, PR77850)

[PATCH] rs6000: Small varargs for BE SVR4 (PR61729, PR77850)

[Segher Boessenkool]

The varargs code for SVR4 puts all (integer) arguments in 4-byte slots.
When it then reads an item from there as something not a multiple of 4
bytes, it needs to adjust the address if big endian.  We didn't yet do
that.

This fixes the g++.dg/abi/scoped1.C, gcc.dg/compat/scalar-by-value-4,
and gcc.dg/compat/scalar-return-4 testcases.

Bootstrapped and tested on powerpc64-linux {-m32,-m64}.  Is this okay
for trunk?


Segher


2017-01-20  Segher Boessenkool  <segher@kernel.crashing.org>

	PR target/61729
	PR target/77850
	* config/rs6000/rs6000.c (rs6000_gimplify_va_arg): Adjust address to
	read from, for big endian.

---
 gcc/config/rs6000/rs6000.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index c5e65d3..381fbb6 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -13685,6 +13685,7 @@ rs6000_gimplify_va_arg (tree valist, tree type, gimple_seq *pre_p,
 
   size = int_size_in_bytes (type);
   rsize = (size + 3) / 4;
+  int pad = 4 * rsize - size;
   align = 1;
 
   machine_mode mode = TYPE_MODE (type);
@@ -13766,6 +13767,10 @@ rs6000_gimplify_va_arg (tree valist, tree type, gimple_seq *pre_p,
 	  && mode == SDmode)
 	t = fold_build_pointer_plus_hwi (t, size);
 
+      /* Args are right-aligned.  */
+      if (BYTES_BIG_ENDIAN)
+	t = fold_build_pointer_plus_hwi (t, pad);
+
       gimplify_assign (addr, t, pre_p);
 
       gimple_seq_add_stmt (pre_p, gimple_build_goto (lab_over));
@@ -13791,6 +13796,11 @@ rs6000_gimplify_va_arg (tree valist, tree type, gimple_seq *pre_p,
       t = build2 (BIT_AND_EXPR, TREE_TYPE (t), t,
 		  build_int_cst (TREE_TYPE (t), -align));
     }
+
+  /* Args are right-aligned.  */
+  if (BYTES_BIG_ENDIAN)
+    t = fold_build_pointer_plus_hwi (t, pad);
+
   gimplify_expr (&t, pre_p, NULL, is_gimple_val, fb_rvalue);
 
   gimplify_assign (unshare_expr (addr), t, pre_p);
-- 
1.9.3