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re PR middle-end/59138 (possible packed struct miscompile)

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PR middle-end/59138
	* expr.c (emit_group_store): Don't write past the end of the structure.
	(store_bit_field): Fix formatting.

From-SVN: r205436
This commit is contained in:
Eric Botcazou 2013-11-27 09:17:23 +00:00 • committed by Eric Botcazou
parent 43ad66aa4a
commit ca85aa4ae6
4 changed files with 61 additions and 9 deletions
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6
gcc/ChangeLog
View file

@ -1,3 +1,9 @@
2013-11-27 Eric Botcazou <ebotcazou@adacore.com>
PR middle-end/59138
* expr.c (emit_group_store): Don't write past the end of the structure.
(store_bit_field): Fix formatting.
2013-11-27 Richard Biener <rguenther@suse.de>
PR tree-optimization/59288

26
gcc/expr.c
View file

@ -2061,12 +2061,14 @@ emit_group_store (rtx orig_dst, rtx src, tree type ATTRIBUTE_UNUSED, int ssize)
HOST_WIDE_INT bytepos = INTVAL (XEXP (XVECEXP (src, 0, i), 1));
enum machine_mode mode = GET_MODE (tmps[i]);
unsigned int bytelen = GET_MODE_SIZE (mode);
unsigned int adj_bytelen = bytelen;
unsigned int adj_bytelen;
rtx dest = dst;
/* Handle trailing fragments that run over the size of the struct. */
if (ssize >= 0 && bytepos + (HOST_WIDE_INT) bytelen > ssize)
adj_bytelen = ssize - bytepos;
else
adj_bytelen = bytelen;
if (GET_CODE (dst) == CONCAT)
{
@ -2107,6 +2109,7 @@ emit_group_store (rtx orig_dst, rtx src, tree type ATTRIBUTE_UNUSED, int ssize)
}
}
/* Handle trailing fragments that run over the size of the struct. */
if (ssize >= 0 && bytepos + (HOST_WIDE_INT) bytelen > ssize)
{
/* store_bit_field always takes its value from the lsb.
@ -2124,16 +2127,22 @@ emit_group_store (rtx orig_dst, rtx src, tree type ATTRIBUTE_UNUSED, int ssize)
tmps[i] = expand_shift (RSHIFT_EXPR, mode, tmps[i],
shift, tmps[i], 0);
}
bytelen = adj_bytelen;
/* Make sure not to write past the end of the struct. */
store_bit_field (dest,
adj_bytelen * BITS_PER_UNIT, bytepos * BITS_PER_UNIT,
bytepos * BITS_PER_UNIT, ssize * BITS_PER_UNIT,
VOIDmode, tmps[i]);
}
/* Optimize the access just a bit. */
if (MEM_P (dest)
&& (! SLOW_UNALIGNED_ACCESS (mode, MEM_ALIGN (dest))
|| MEM_ALIGN (dest) >= GET_MODE_ALIGNMENT (mode))
&& bytepos * BITS_PER_UNIT % GET_MODE_ALIGNMENT (mode) == 0
&& bytelen == GET_MODE_SIZE (mode))
else if (MEM_P (dest)
&& (!SLOW_UNALIGNED_ACCESS (mode, MEM_ALIGN (dest))
|| MEM_ALIGN (dest) >= GET_MODE_ALIGNMENT (mode))
&& bytepos * BITS_PER_UNIT % GET_MODE_ALIGNMENT (mode) == 0
&& bytelen == GET_MODE_SIZE (mode))
emit_move_insn (adjust_address (dest, mode, bytepos), tmps[i]);
else
store_bit_field (dest, bytelen * BITS_PER_UNIT, bytepos * BITS_PER_UNIT,
0, 0, mode, tmps[i]);
@ -4776,8 +4785,7 @@ expand_assignment (tree to, tree from, bool nontemporal)
expand_insn (icode, 2, ops);
}
else
store_bit_field (mem, GET_MODE_BITSIZE (mode),
0, 0, 0, mode, reg);
store_bit_field (mem, GET_MODE_BITSIZE (mode), 0, 0, 0, mode, reg);
return;
}

4
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,7 @@
2013-11-27 Eric Botcazou <ebotcazou@adacore.com>
* gcc.c-torture/execute/20131127-1.c: New test.
2013-11-27 Richard Biener <rguenther@suse.de>
PR tree-optimization/59288

34
gcc/testsuite/gcc.c-torture/execute/20131127-1.c Normal file
View file

@ -0,0 +1,34 @@
/* PR middle-end/59138 */
/* Testcase by John Regehr <regehr@cs.utah.edu> */
extern void abort (void);
#pragma pack(1)
struct S0 {
int f0;
int f1;
int f2;
short f3;
};
short a = 1;
struct S0 b = { 1 }, c, d, e;
struct S0 fn1() { return c; }
void fn2 (void)
{
b = fn1 ();
a = 0;
d = e;
}
int main (void)
{
fn2 ();
if (a != 0)
abort ();
return 0;
}