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

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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
This commit is contained in:
J"orn Rennecke 2006-09-01 20:25:34 +00:00 committed by Richard Biener
parent cd709ec369
commit 537b8a357c
5 changed files with 95 additions and 9 deletions
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9
gcc/ChangeLog
View File

@ -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

49
gcc/builtins.c
View File

@ -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);

8
gcc/testsuite/ChangeLog
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@ -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

19
gcc/testsuite/gcc.dg/pr27226.c Normal file
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@ -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" } } */

19
gcc/testsuite/gcc.target/mips/memcpy-1.c Normal file
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@ -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);
}