re PR middle-end/27226 (Compiler looses track of alignment for emit_block_move)

2006-09-01  J"orn Rennecke  <joern.rennecke@st.com>
	Richard Guenther  <rguenther@suse.de>
	Adam Nemet  <anemet@caviumnetworks.com>

	PR middle-end/27226
	* builtins.c (get_pointer_alignment): Handle more forms
	of base addresses that can be used to derive more precise
	information about alignment.

	* gcc.target/mips/memcpy-1.c: New testcase.
	* gcc.dg/pr27226.c: Likewise.

Co-Authored-By: Adam Nemet <anemet@caviumnetworks.com>
Co-Authored-By: Richard Guenther <rguenther@suse.de>

From-SVN: r116641

gcc/ChangeLog

@@ -1,3 +1,12 @@
+2006-09-01  J"orn Rennecke  <joern.rennecke@st.com>
+	Richard Guenther  <rguenther@suse.de>
+	Adam Nemet  <anemet@caviumnetworks.com>
+
+	PR middle-end/27226
+	* builtins.c (get_pointer_alignment): Handle more forms
+	of base addresses that can be used to derive more precise
+	information about alignment.
+
 2006-09-01  Jason Merrill  <jason@redhat.com>
 
 	PR c++/28899

gcc/builtins.c

@@ -275,16 +275,44 @@ get_pointer_alignment (tree exp, unsigned int max_align)
 	  /* See what we are pointing at and look at its alignment.  */
 	  exp = TREE_OPERAND (exp, 0);
 	  inner = max_align;
-	  while (handled_component_p (exp))
+	  if (handled_component_p (exp))
 	    {
-	      /* Fields in a structure can be packed, honor DECL_ALIGN
-		 of the FIELD_DECL.  For all other references the conservative
-		 alignment is the element type alignment.  */
-	      if (TREE_CODE (exp) == COMPONENT_REF)
-		inner = MIN (inner, DECL_ALIGN (TREE_OPERAND (exp, 1)));
-	      else
-		inner = MIN (inner, TYPE_ALIGN (TREE_TYPE (exp)));
-	      exp = TREE_OPERAND (exp, 0);
+	      HOST_WIDE_INT bitsize, bitpos;
+	      tree offset;
+	      enum machine_mode mode; 
+	      int unsignedp, volatilep;
+
+	      exp = get_inner_reference (exp, &bitsize, &bitpos, &offset,
+					 &mode, &unsignedp, &volatilep, true);
+	      if (bitpos)
+		inner = MIN (inner, (unsigned) (bitpos & -bitpos));
+	      if (offset && TREE_CODE (offset) == PLUS_EXPR
+		  && host_integerp (TREE_OPERAND (offset, 1), 1))
+	        {
+		  /* Any overflow in calculating offset_bits won't change
+		     the alignment.  */
+		  unsigned offset_bits
+		    = ((unsigned) tree_low_cst (TREE_OPERAND (offset, 1), 1)
+		       * BITS_PER_UNIT);
+
+		  if (offset_bits)
+		    inner = MIN (inner, (offset_bits & -offset_bits));
+		  offset = TREE_OPERAND (offset, 0);
+		}
+	      if (offset && TREE_CODE (offset) == MULT_EXPR
+		  && host_integerp (TREE_OPERAND (offset, 1), 1))
+	        {
+		  /* Any overflow in calculating offset_factor won't change
+		     the alignment.  */
+		  unsigned offset_factor
+		    = ((unsigned) tree_low_cst (TREE_OPERAND (offset, 1), 1)
+		       * BITS_PER_UNIT);
+
+		  if (offset_factor)
+		    inner = MIN (inner, (offset_factor & -offset_factor));
+		}
+	      else if (offset)
+		inner = MIN (inner, BITS_PER_UNIT);
 	    }
 	  if (TREE_CODE (exp) == FUNCTION_DECL)
 	    align = FUNCTION_BOUNDARY;
@@ -294,6 +322,9 @@ get_pointer_alignment (tree exp, unsigned int max_align)
 	  else if (CONSTANT_CLASS_P (exp))
 	    align = MIN (inner, (unsigned)CONSTANT_ALIGNMENT (exp, align));
 #endif
+	  else if (TREE_CODE (exp) == VIEW_CONVERT_EXPR
+		   || TREE_CODE (exp) == INDIRECT_REF)
+	    align = MIN (TYPE_ALIGN (TREE_TYPE (exp)), inner);
 	  else
 	    align = MIN (align, inner);
 	  return MIN (align, max_align);

gcc/testsuite/ChangeLog

@@ -1,3 +1,11 @@
+2006-09-01  J"orn Rennecke  <joern.rennecke@st.com>
+	Richard Guenther  <rguenther@suse.de>
+	Adam Nemet  <anemet@caviumnetworks.com>
+
+	PR middle-end/27226
+	* gcc.target/mips/memcpy-1.c: New testcase.
+	* gcc.dg/pr27226.c: Likewise.
+
 2006-09-01  Nathan Sidwell  <nathan@codesourcery.com>
 
 	PR c++/28705

gcc/testsuite/gcc.dg/pr27226.c

@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+char *strcpy (char *, const char *);
+
+extern void g ();
+
+f ()
+{
+  struct {
+    int i;
+    char str[31];
+  } s;
+
+  strcpy (s.str, "text text text text text text text text");
+  g (s.str);
+}
+
+/* { dg-final { scan-assembler-not "memcpy" } } */

gcc/testsuite/gcc.target/mips/memcpy-1.c

@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-mips-options "-O2" } */
+/* { dg-final { scan-assembler-not "\tlbu\t" } } */
+
+#include <string.h>
+
+char c[10];
+
+void
+f1 ()
+{
+  memcpy (c, "123456", 6);
+}
+
+void
+f2 ()
+{
+  memcpy (c, &"12345678"[2], 6);
+}