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re PR sanitizer/58413 (ubsan constant folding)

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PR sanitizer/58413
c-family/
	* c-ubsan.c (ubsan_instrument_shift): Don't instrument
	an expression if we can prove it is correct.
	(ubsan_instrument_division): Likewise.  Remove unnecessary
	check.
testsuite/
	* c-c++-common/ubsan/shift-5.c: New test.
	* c-c++-common/ubsan/shift-6.c: New test.
	* c-c++-common/ubsan/div-by-zero-5.c: New test.
	* gcc.dg/ubsan/c-shift-1.c: New test.


Co-Authored-By: Jakub Jelinek <jakub@redhat.com>

From-SVN: r202886
This commit is contained in:
Marek Polacek 2013-09-25 08:58:57 +00:00 committed by Marek Polacek
parent 550dfe7f28
commit b56e978833
7 changed files with 116 additions and 8 deletions
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9
gcc/c-family/ChangeLog
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@ -1,3 +1,12 @@
2013-09-25 Marek Polacek <polacek@redhat.com>
Jakub Jelinek <jakub@redhat.com>
PR sanitizer/58413
* c-ubsan.c (ubsan_instrument_shift): Don't instrument
an expression if we can prove it is correct.
(ubsan_instrument_division): Likewise. Remove unnecessary
check.
2013-09-18 Marek Polacek <polacek@redhat.com>
PR sanitizer/58411

18
gcc/c-family/c-ubsan.c
View File

@ -51,14 +51,6 @@ ubsan_instrument_division (location_t loc, tree op0, tree op1)
if (TREE_CODE (type) != INTEGER_TYPE)
return NULL_TREE;
/* If we *know* that the divisor is not -1 or 0, we don't have to
instrument this expression.
??? We could use decl_constant_value to cover up more cases. */
if (TREE_CODE (op1) == INTEGER_CST
&& integer_nonzerop (op1)
&& !integer_minus_onep (op1))
return NULL_TREE;
t = fold_build2 (EQ_EXPR, boolean_type_node,
op1, build_int_cst (type, 0));
@ -74,6 +66,11 @@ ubsan_instrument_division (location_t loc, tree op0, tree op1)
t = fold_build2 (TRUTH_OR_EXPR, boolean_type_node, t, x);
}
/* If the condition was folded to 0, no need to instrument
this expression. */
if (integer_zerop (t))
return NULL_TREE;
/* In case we have a SAVE_EXPR in a conditional context, we need to
make sure it gets evaluated before the condition. */
t = fold_build2 (COMPOUND_EXPR, TREE_TYPE (t), op0, t);
@ -138,6 +135,11 @@ ubsan_instrument_shift (location_t loc, enum tree_code code,
tt = fold_build2 (TRUTH_OR_EXPR, boolean_type_node, x, tt);
}
/* If the condition was folded to 0, no need to instrument
this expression. */
if (integer_zerop (t) && (tt == NULL_TREE || integer_zerop (tt)))
return NULL_TREE;
/* In case we have a SAVE_EXPR in a conditional context, we need to
make sure it gets evaluated before the condition. */
t = fold_build2 (COMPOUND_EXPR, TREE_TYPE (t), op0, t);

8
gcc/testsuite/ChangeLog
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@ -1,3 +1,11 @@
2013-09-25 Marek Polacek <polacek@redhat.com>
PR sanitizer/58413
* c-c++-common/ubsan/shift-5.c: New test.
* c-c++-common/ubsan/shift-6.c: New test.
* c-c++-common/ubsan/div-by-zero-5.c: New test.
* gcc.dg/ubsan/c-shift-1.c: New test.
2013-09-25 Marek Polacek <polacek@redhat.com>
PR c++/58516

8
gcc/testsuite/c-c++-common/ubsan/div-by-zero-5.c Normal file
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@ -0,0 +1,8 @@
/* { dg-do compile} */
/* { dg-options "-fsanitize=integer-divide-by-zero" } */
void
foo (void)
{
int A[-2 / -1] = {};
}

33
gcc/testsuite/c-c++-common/ubsan/shift-5.c Normal file
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@ -0,0 +1,33 @@
/* { dg-do compile } */
/* { dg-options "-fsanitize=shift -w" } */
/* { dg-shouldfail "ubsan" } */
int x;
int
foo (void)
{
/* None of the following should pass. */
switch (x)
{
case 1 >> -1:
/* { dg-error "case label does not reduce to an integer constant" "" {target c } 12 } */
/* { dg-error "is not a constant expression" "" { target c++ } 12 } */
case -1 >> -1:
/* { dg-error "case label does not reduce to an integer constant" "" {target c } 15 } */
/* { dg-error "is not a constant expression" "" { target c++ } 15 } */
case 1 << -1:
/* { dg-error "case label does not reduce to an integer constant" "" {target c } 18 } */
/* { dg-error "is not a constant expression" "" { target c++ } 18 } */
case -1 << -1:
/* { dg-error "case label does not reduce to an integer constant" "" {target c } 21 } */
/* { dg-error "is not a constant expression" "" { target c++ } 21 } */
case -1 >> 200:
/* { dg-error "case label does not reduce to an integer constant" "" {target c } 24 } */
/* { dg-error "is not a constant expression" "" { target c++ } 24 } */
case 1 << 200:
/* { dg-error "case label does not reduce to an integer constant" "" {target c } 27 } */
/* { dg-error "is not a constant expression" "" { target c++ } 27 } */
return 1;
}
return 0;
}

30
gcc/testsuite/c-c++-common/ubsan/shift-6.c Normal file
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@ -0,0 +1,30 @@
/* PR sanitizer/58413 */
/* { dg-do run { target int32plus } } */
/* { dg-options "-fsanitize=shift -w" } */
int x = 7;
int
main (void)
{
/* All of the following should pass. */
int A[128 >> 5] = {};
int B[128 << 5] = {};
static int e =
((int)
(0x00000000 | ((31 & ((1 << (4)) - 1)) << (((15) + 6) + 4)) |
((0) << ((15) + 6)) | ((0) << (15))));
if (e != 503316480)
__builtin_abort ();
switch (x)
{
case 1 >> 4:
case 1 << 4:
case 128 << (4 + 1):
case 128 >> (4 + 1):
return 1;
}
return 0;
}

18
gcc/testsuite/gcc.dg/ubsan/c-shift-1.c Normal file
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@ -0,0 +1,18 @@
/* { dg-do compile} */
/* { dg-options "-fsanitize=shift -w" } */
/* { dg-shouldfail "ubsan" } */
int x;
int
main (void)
{
/* None of the following should pass. */
int A[1 >> -1] = {}; /* { dg-error "variable-sized object may not be initialized" } */
int B[-1 >> -1] = {}; /* { dg-error "variable-sized object may not be initialized" } */
int D[1 << -1] = {}; /* { dg-error "variable-sized object may not be initialized" } */
int E[-1 << -1] = {}; /* { dg-error "variable-sized object may not be initialized" } */
int F[-1 >> 200] = {}; /* { dg-error "variable-sized object may not be initialized" } */
int G[1 << 200] = {}; /* { dg-error "variable-sized object may not be initialized" } */
return 0;
}