re PR middle-end/42834 (memcpy folding overeager)

[thirdparty/gcc.git] / gcc / emit-rtl.c

diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
index 55ed2054e4e703947b5bc75d4147aa982fc5b14e..4e38d89d34875f973f2b96aa90a8fb9be4abeb14 100644 (file)
--- a/gcc/emit-rtl.c
+++ b/gcc/emit-rtl.c
@@ -1614,6 +1614,35 @@ set_mem_attributes_minus_bitpos (rtx ref, tree t, int objectp,
       || TREE_CODE (t) == ALIGN_INDIRECT_REF
       || TYPE_ALIGN_OK (type))
     align = MAX (align, TYPE_ALIGN (type));
+  else if (TREE_CODE (t) == MEM_REF)
+    {
+      HOST_WIDE_INT aoff = BITS_PER_UNIT;
+      if (host_integerp (TREE_OPERAND (t, 1), 1))
+       {
+         HOST_WIDE_INT ioff = TREE_INT_CST_LOW (TREE_OPERAND (t, 1));
+         aoff = (ioff & -ioff) * BITS_PER_UNIT;
+       }
+      if (TREE_CODE (TREE_OPERAND (t, 0)) == ADDR_EXPR
+         && DECL_P (TREE_OPERAND (TREE_OPERAND (t, 0), 0)))
+       align = MAX (align,
+                    DECL_ALIGN (TREE_OPERAND (TREE_OPERAND (t, 0), 0)));
+      else if (TREE_CODE (TREE_OPERAND (t, 0)) == ADDR_EXPR
+              && CONSTANT_CLASS_P (TREE_OPERAND (TREE_OPERAND (t, 0), 0)))
+       {
+         align = TYPE_ALIGN (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (t, 0), 0)));
+#ifdef CONSTANT_ALIGNMENT
+         align = CONSTANT_ALIGNMENT (TREE_OPERAND (TREE_OPERAND (t, 0), 0), align);
+#endif
+       }
+      else
+       /* This technically isn't correct.  We can't really derive
+          alignment information from types.  */
+       align = MAX (align,
+                    TYPE_ALIGN (TREE_TYPE (TREE_TYPE (TREE_OPERAND (t, 1)))));
+      if (!integer_zerop (TREE_OPERAND (t, 1))
+         && aoff < align)
+       align = aoff;
+    }
   else
     if (TREE_CODE (t) == MISALIGNED_INDIRECT_REF)
       {
@@ -1654,6 +1683,9 @@ set_mem_attributes_minus_bitpos (rtx ref, tree t, int objectp,
             || TREE_CODE (base) == BIT_FIELD_REF)
        base = TREE_OPERAND (base, 0);
 
+      if (TREE_CODE (base) == MEM_REF
+         && TREE_CODE (TREE_OPERAND (base, 0)) == ADDR_EXPR)
+       base = TREE_OPERAND (TREE_OPERAND (base, 0), 0);
       if (DECL_P (base))
        {
          if (CODE_CONTAINS_STRUCT (TREE_CODE (base), TS_DECL_WITH_VIS))
@@ -1774,7 +1806,7 @@ set_mem_attributes_minus_bitpos (rtx ref, tree t, int objectp,
            }
 
          /* If this is an indirect reference, record it.  */
-         else if (TREE_CODE (t) == INDIRECT_REF
+         else if (TREE_CODE (t) == MEM_REF 
                   || TREE_CODE (t) == MISALIGNED_INDIRECT_REF)
            {
              expr = t;
@@ -1784,7 +1816,7 @@ set_mem_attributes_minus_bitpos (rtx ref, tree t, int objectp,
        }
 
       /* If this is an indirect reference, record it.  */
-      else if (TREE_CODE (t) == INDIRECT_REF
+      else if (TREE_CODE (t) == MEM_REF 
               || TREE_CODE (t) == MISALIGNED_INDIRECT_REF)
        {
          expr = t;