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[PATCH] Fix some undefined behavior spots in gcc sources (PR c/53968)
- From: Jakub Jelinek <jakub at redhat dot com>
- To: gcc-patches at gcc dot gnu dot org
- Cc: John Regehr <regehr at cs dot utah dot edu>
- Date: Mon, 13 Aug 2012 14:01:34 +0200
- Subject: [PATCH] Fix some undefined behavior spots in gcc sources (PR c/53968)
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
Hi!
John Regehr discovered a couple of spots in GCC sources that invoke
undefined behavior during bootstrap/regtest, the following patch fixes most
of them. I couldn't reproduce the diagnostic.c failure and would like to
leave the ipa hunk to Honza, I think the probability/frequency code often
might go out of the expected limits and then invoke undefined signed
overflow.
The double_int_mask change is because e.g. with -E, ptr_mode is VOIDmode and
so double_int_mask is called with 0 precision during compiler
initialization.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2012-08-13 Jakub Jelinek <jakub@redhat.com>
PR c/53968
* tree.c (integer_pow2p): Avoid undefined signed overflows.
* simplify-rtx.c (neg_const_int): Likewise.
* expr.c (fixup_args_size_notes): Likewise.
* stor-layout.c (set_min_and_max_values_for_integral_type): Likewise.
* double-int.c (mul_double_wide_with_sign): Likewise.
(double_int_mask): Likewise.
* tree-ssa-loop-ivopts.c (get_address_cost): Likewise.
--- gcc/tree.c.jj 2012-08-10 15:48:53.000000000 +0200
+++ gcc/tree.c 2012-08-13 10:25:46.610502929 +0200
@@ -1849,7 +1849,7 @@ int
integer_pow2p (const_tree expr)
{
int prec;
- HOST_WIDE_INT high, low;
+ unsigned HOST_WIDE_INT high, low;
STRIP_NOPS (expr);
--- gcc/simplify-rtx.c.jj 2012-08-10 15:49:20.000000000 +0200
+++ gcc/simplify-rtx.c 2012-08-13 09:51:43.628508537 +0200
@@ -66,7 +66,7 @@ static rtx simplify_binary_operation_1 (
static rtx
neg_const_int (enum machine_mode mode, const_rtx i)
{
- return gen_int_mode (- INTVAL (i), mode);
+ return gen_int_mode (-(unsigned HOST_WIDE_INT) INTVAL (i), mode);
}
/* Test whether expression, X, is an immediate constant that represents
--- gcc/expr.c.jj 2012-08-10 15:49:07.000000000 +0200
+++ gcc/expr.c 2012-08-13 10:40:01.182501639 +0200
@@ -3828,7 +3828,7 @@ fixup_args_size_notes (rtx prev, rtx las
add_reg_note (insn, REG_ARGS_SIZE, GEN_INT (args_size));
#ifdef STACK_GROWS_DOWNWARD
- this_delta = -this_delta;
+ this_delta = -(unsigned HOST_WIDE_INT) this_delta;
#endif
args_size -= this_delta;
}
--- gcc/stor-layout.c.jj 2012-08-10 15:49:20.000000000 +0200
+++ gcc/stor-layout.c 2012-08-13 10:14:14.388505253 +0200
@@ -2568,10 +2568,14 @@ set_min_and_max_values_for_integral_type
= build_int_cst_wide (type,
(precision - HOST_BITS_PER_WIDE_INT > 0
? -1
- : ((HOST_WIDE_INT) 1 << (precision - 1)) - 1),
+ : (HOST_WIDE_INT)
+ (((unsigned HOST_WIDE_INT) 1
+ << (precision - 1)) - 1)),
(precision - HOST_BITS_PER_WIDE_INT - 1 > 0
- ? (((HOST_WIDE_INT) 1
- << (precision - HOST_BITS_PER_WIDE_INT - 1))) - 1
+ ? (HOST_WIDE_INT)
+ ((((unsigned HOST_WIDE_INT) 1
+ << (precision - HOST_BITS_PER_WIDE_INT
+ - 1))) - 1)
: 0));
}
--- gcc/double-int.c.jj 2012-08-10 15:49:07.000000000 +0200
+++ gcc/double-int.c 2012-08-13 11:24:17.816495757 +0200
@@ -170,7 +170,7 @@ mul_double_wide_with_sign (unsigned HOST
{
k = i + j;
/* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
- carry += arg1[i] * arg2[j];
+ carry += (unsigned HOST_WIDE_INT) arg1[i] * arg2[j];
/* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
carry += prod[k];
prod[k] = LOWPART (carry);
@@ -625,7 +625,7 @@ double_int_mask (unsigned prec)
else
{
mask.high = 0;
- mask.low = ((unsigned HOST_WIDE_INT) 2 << (prec - 1)) - 1;
+ mask.low = prec ? ((unsigned HOST_WIDE_INT) 2 << (prec - 1)) - 1 : 0;
}
return mask;
--- gcc/tree-ssa-loop-ivopts.c.jj 2012-08-10 15:49:07.000000000 +0200
+++ gcc/tree-ssa-loop-ivopts.c 2012-08-13 10:17:51.227504425 +0200
@@ -3173,7 +3173,7 @@ get_address_cost (bool symbol_present, b
for (i = width; i >= 0; i--)
{
- off = -((HOST_WIDE_INT) 1 << i);
+ off = -((unsigned HOST_WIDE_INT) 1 << i);
XEXP (addr, 1) = gen_int_mode (off, address_mode);
if (memory_address_addr_space_p (mem_mode, addr, as))
break;
@@ -3182,7 +3182,7 @@ get_address_cost (bool symbol_present, b
for (i = width; i >= 0; i--)
{
- off = ((HOST_WIDE_INT) 1 << i) - 1;
+ off = ((unsigned HOST_WIDE_INT) 1 << i) - 1;
XEXP (addr, 1) = gen_int_mode (off, address_mode);
if (memory_address_addr_space_p (mem_mode, addr, as))
break;
Jakub