PR middle-end/51994

[pf3gnuchains/gcc-fork.git] / gcc / expr.c

diff --git a/gcc/expr.c b/gcc/expr.c
index fcf177b..e63ed3b 100644 (file)
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -6716,6 +6716,24 @@ get_inner_reference (tree exp, HOST_WIDE_INT *pbitsize,
   /* Otherwise, split it up.  */
   if (offset)
     {
+      /* Avoid returning a negative bitpos as this may wreak havoc later.  */
+      if (double_int_negative_p (bit_offset))
+        {
+         double_int mask
+           = double_int_mask (BITS_PER_UNIT == 8
+                              ? 3 : exact_log2 (BITS_PER_UNIT));
+         double_int tem = double_int_and_not (bit_offset, mask);
+         /* TEM is the bitpos rounded to BITS_PER_UNIT towards -Inf.
+            Subtract it to BIT_OFFSET and add it (scaled) to OFFSET.  */
+         bit_offset = double_int_sub (bit_offset, tem);
+         tem = double_int_rshift (tem,
+                                  BITS_PER_UNIT == 8
+                                  ? 3 : exact_log2 (BITS_PER_UNIT),
+                                  HOST_BITS_PER_DOUBLE_INT, true);
+         offset = size_binop (PLUS_EXPR, offset,
+                              double_int_to_tree (sizetype, tem));
+       }
+
       *pbitpos = double_int_to_shwi (bit_offset);
       *poffset = offset;
     }