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2011-07-08 Richard Sandiford <rdsandiford@googlemail.com>
gcc/
* builtins.c (get_object_alignment): Fix comment.
* fold-const.c (get_pointer_modulus_and_residue): Remove
allow_func_align. Use get_object_alignment.
(fold_binary_loc): Update caller.
2011-07-08 Richard Sandiford <rdsandiford@googlemail.com>
gcc/
Backport from mainline:
2011-06-29 Richard Sandiford <richard.sandiford@linaro.org>
PR tree-optimization/49545
* builtins.c (get_object_alignment_1): Update function comment.
Do not use DECL_ALIGN for functions, but test
TARGET_PTRMEMFUNC_VBIT_LOCATION instead.
* fold-const.c (get_pointer_modulus_and_residue): Don't check
for functions here.
gcc/testsuite/
Backport from mainline:
2011-06-29 Richard Sandiford <richard.sandiford@linaro.org>
* gcc.dg/torture/pr49169.c: Restrict to ARM and MIPS targets.
2011-07-08 Richard Sandiford <richard.sandiford@linaro.org>
gcc/
Backport from mainline:
2011-07-27 Richard Guenther <rguenther@suse.de>
PR tree-optimization/49169
* fold-const.c (get_pointer_modulus_and_residue): Don't rely on
the alignment of function decls.
gcc/testsuite/
Backport from mainline:
2011-07-27 Michael Hope <michael.hope@linaro.org>
Richard Sandiford <richard.sandiford@linaro.org>
PR tree-optimization/49169
* gcc.dg/torture/pr49169.c: New test.
=== modified file 'gcc/builtins.c'
--- old/gcc/builtins.c 2011-01-06 11:02:44 +0000
+++ new/gcc/builtins.c 2011-06-29 09:59:48 +0000
@@ -263,7 +263,14 @@
/* Return the alignment in bits of EXP, an object.
Don't return more than MAX_ALIGN no matter what, ALIGN is the inital
- guessed alignment e.g. from type alignment. */
+ guessed alignment e.g. from type alignment.
+
+ Note that the address (and thus the alignment) computed here is based
+ on the address to which a symbol resolves, whereas DECL_ALIGN is based
+ on the address at which an object is actually located. These two
+ addresses are not always the same. For example, on ARM targets,
+ the address &foo of a Thumb function foo() has the lowest bit set,
+ whereas foo() itself starts on an even address. */
int
get_object_alignment (tree exp, unsigned int align, unsigned int max_align)
@@ -327,7 +334,21 @@
exp = DECL_INITIAL (exp);
if (DECL_P (exp)
&& TREE_CODE (exp) != LABEL_DECL)
- align = MIN (inner, DECL_ALIGN (exp));
+ {
+ if (TREE_CODE (exp) == FUNCTION_DECL)
+ {
+ /* Function addresses can encode extra information besides their
+ alignment. However, if TARGET_PTRMEMFUNC_VBIT_LOCATION
+ allows the low bit to be used as a virtual bit, we know
+ that the address itself must be 2-byte aligned. */
+ if (TARGET_PTRMEMFUNC_VBIT_LOCATION == ptrmemfunc_vbit_in_pfn)
+ align = 2 * BITS_PER_UNIT;
+ else
+ align = BITS_PER_UNIT;
+ }
+ else
+ align = MIN (inner, DECL_ALIGN (exp));
+ }
#ifdef CONSTANT_ALIGNMENT
else if (CONSTANT_CLASS_P (exp))
align = MIN (inner, (unsigned)CONSTANT_ALIGNMENT (exp, align));
=== modified file 'gcc/fold-const.c'
--- old/gcc/fold-const.c 2011-05-05 14:28:53 +0000
+++ new/gcc/fold-const.c 2011-07-08 12:54:44 +0000
@@ -10030,15 +10030,10 @@
0 <= N < M as is common. In general, the precise value of P is unknown.
M is chosen as large as possible such that constant N can be determined.
- Returns M and sets *RESIDUE to N.
-
- If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
- account. This is not always possible due to PR 35705.
- */
+ Returns M and sets *RESIDUE to N. */
static unsigned HOST_WIDE_INT
-get_pointer_modulus_and_residue (tree expr, unsigned HOST_WIDE_INT *residue,
- bool allow_func_align)
+get_pointer_modulus_and_residue (tree expr, unsigned HOST_WIDE_INT *residue)
{
enum tree_code code;
@@ -10068,9 +10063,8 @@
}
}
- if (DECL_P (expr)
- && (allow_func_align || TREE_CODE (expr) != FUNCTION_DECL))
- return DECL_ALIGN_UNIT (expr);
+ if (DECL_P (expr))
+ return get_object_alignment (expr, BITS_PER_UNIT, ~0U) / BITS_PER_UNIT;
}
else if (code == POINTER_PLUS_EXPR)
{
@@ -10080,8 +10074,7 @@
op0 = TREE_OPERAND (expr, 0);
STRIP_NOPS (op0);
- modulus = get_pointer_modulus_and_residue (op0, residue,
- allow_func_align);
+ modulus = get_pointer_modulus_and_residue (op0, residue);
op1 = TREE_OPERAND (expr, 1);
STRIP_NOPS (op1);
@@ -11801,8 +11794,7 @@
unsigned HOST_WIDE_INT modulus, residue;
unsigned HOST_WIDE_INT low = TREE_INT_CST_LOW (arg1);
- modulus = get_pointer_modulus_and_residue (arg0, &residue,
- integer_onep (arg1));
+ modulus = get_pointer_modulus_and_residue (arg0, &residue);
/* This works because modulus is a power of 2. If this weren't the
case, we'd have to replace it by its greatest power-of-2
=== added file 'gcc/testsuite/gcc.dg/torture/pr49169.c'
--- old/gcc/testsuite/gcc.dg/torture/pr49169.c 1970-01-01 00:00:00 +0000
+++ new/gcc/testsuite/gcc.dg/torture/pr49169.c 2011-06-29 09:59:48 +0000
@@ -0,0 +1,15 @@
+/* { dg-do compile { target { arm*-*-* || mips*-*-* } } } */
+
+#include <stdlib.h>
+#include <stdint.h>
+
+int
+main (void)
+{
+ void *p = main;
+ if ((intptr_t) p & 1)
+ abort ();
+ return 0;
+}
+
+/* { dg-final { scan-assembler "abort" } } */
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