* Re: [PATCH] middle-end/108995 - avoid folding when sanitizing overflow
[not found] <20230308093849.51C183858C62@sourceware.org>
@ 2023-03-09 13:10 ` Jakub Jelinek
2023-03-09 13:29 ` Richard Biener
0 siblings, 1 reply; 3+ messages in thread
From: Jakub Jelinek @ 2023-03-09 13:10 UTC (permalink / raw)
To: Richard Biener; +Cc: gcc-patches
On Wed, Mar 08, 2023 at 09:38:43AM +0000, Richard Biener via Gcc-patches wrote:
> The following plugs one place in extract_muldiv where it should avoid
> folding when sanitizing overflow.
>
> I'm unsure about the testcase, I didn't find any that tests for
> a runtime sanitizer error ...
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu.
>
> OK?
>
> PR middle-end/108995
> * fold-const.cc (extract_muldiv_1): Avoid folding
> (CST * b) / CST2 when sanitizing overflow and we rely on
> overflow being undefined.
This is ok.
>
> * gcc.dg/ubsan/pr108995.c: New testcase.
As for testcase, there are many testcases that test for runtime sanitizer
errors. For ubsan, it is more common to test -fsanitize-recover= and
just dg-output scan the output for expected diagnostics (many examples
in that directory).
Another possibility is to test for the no recovery, see e.g.
gcc.dg/ubsan/bounds-3.c. In that case there should be
/* { dg-do run } */
and
/* { dg-shouldfail "ubsan" } */
but dg-output checking for the exact wording is still highly desirable.
The test also relies on 32-bit ints, so it should be dg-do run { target int32 }
I think.
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/ubsan/pr108995.c
> @@ -0,0 +1,15 @@
> +/* { dg-do run { xfail *-*-* } } */
> +/* With optimization we constant fold and diagnose the overflow and do
> + not sanitize anything. */
> +/* { dg-skip-if "" { *-*-* } { "*" } { ! "-O0" } } */
> +/* { dg-options "-fsanitize=undefined -fno-sanitize-recover=undefined" } */
> +
> +int a;
> +const int b = 44514;
> +int *c = &a;
> +
> +int main ()
> +{
> + *c = 65526 * b / 6;
> + return 0;
> +}
> --
> 2.35.3
Jakub
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] middle-end/108995 - avoid folding when sanitizing overflow
2023-03-09 13:10 ` [PATCH] middle-end/108995 - avoid folding when sanitizing overflow Jakub Jelinek
@ 2023-03-09 13:29 ` Richard Biener
0 siblings, 0 replies; 3+ messages in thread
From: Richard Biener @ 2023-03-09 13:29 UTC (permalink / raw)
To: Jakub Jelinek; +Cc: gcc-patches
On Thu, 9 Mar 2023, Jakub Jelinek wrote:
> On Wed, Mar 08, 2023 at 09:38:43AM +0000, Richard Biener via Gcc-patches wrote:
> > The following plugs one place in extract_muldiv where it should avoid
> > folding when sanitizing overflow.
> >
> > I'm unsure about the testcase, I didn't find any that tests for
> > a runtime sanitizer error ...
> >
> > Bootstrapped and tested on x86_64-unknown-linux-gnu.
> >
> > OK?
> >
> > PR middle-end/108995
> > * fold-const.cc (extract_muldiv_1): Avoid folding
> > (CST * b) / CST2 when sanitizing overflow and we rely on
> > overflow being undefined.
>
> This is ok.
>
> >
> > * gcc.dg/ubsan/pr108995.c: New testcase.
>
> As for testcase, there are many testcases that test for runtime sanitizer
> errors. For ubsan, it is more common to test -fsanitize-recover= and
> just dg-output scan the output for expected diagnostics (many examples
> in that directory).
> Another possibility is to test for the no recovery, see e.g.
> gcc.dg/ubsan/bounds-3.c. In that case there should be
> /* { dg-do run } */
> and
> /* { dg-shouldfail "ubsan" } */
> but dg-output checking for the exact wording is still highly desirable.
>
> The test also relies on 32-bit ints, so it should be dg-do run { target int32 }
> I think.
OK, the following is what I have applied.
Richard.
From ace65db9215882b95e2ead1bb0dc8c54c2ea69be Mon Sep 17 00:00:00 2001
From: Richard Biener <rguenther@suse.de>
Date: Wed, 8 Mar 2023 09:06:44 +0100
Subject: [PATCH] middle-end/108995 - avoid folding when sanitizing overflow
To: gcc-patches@gcc.gnu.org
The following plugs one place in extract_muldiv where it should avoid
folding when sanitizing overflow.
PR middle-end/108995
* fold-const.cc (extract_muldiv_1): Avoid folding
(CST * b) / CST2 when sanitizing overflow and we rely on
overflow being undefined.
* gcc.dg/ubsan/pr108995.c: New testcase.
---
gcc/fold-const.cc | 7 +++----
gcc/testsuite/gcc.dg/ubsan/pr108995.c | 18 ++++++++++++++++++
2 files changed, 21 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/ubsan/pr108995.c
diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc
index 99882ef820a..02a24c5fe65 100644
--- a/gcc/fold-const.cc
+++ b/gcc/fold-const.cc
@@ -7093,6 +7093,7 @@ extract_muldiv_1 (tree t, tree c, enum tree_code code, tree wide_type,
If we have an unsigned type, we cannot do this since it will change
the result if the original computation overflowed. */
if (TYPE_OVERFLOW_UNDEFINED (ctype)
+ && !TYPE_OVERFLOW_SANITIZED (ctype)
&& ((code == MULT_EXPR && tcode == EXACT_DIV_EXPR)
|| (tcode == MULT_EXPR
&& code != TRUNC_MOD_EXPR && code != CEIL_MOD_EXPR
@@ -7102,8 +7103,7 @@ extract_muldiv_1 (tree t, tree c, enum tree_code code, tree wide_type,
if (wi::multiple_of_p (wi::to_wide (op1), wi::to_wide (c),
TYPE_SIGN (type)))
{
- if (TYPE_OVERFLOW_UNDEFINED (ctype))
- *strict_overflow_p = true;
+ *strict_overflow_p = true;
return fold_build2 (tcode, ctype, fold_convert (ctype, op0),
fold_convert (ctype,
const_binop (TRUNC_DIV_EXPR,
@@ -7112,8 +7112,7 @@ extract_muldiv_1 (tree t, tree c, enum tree_code code, tree wide_type,
else if (wi::multiple_of_p (wi::to_wide (c), wi::to_wide (op1),
TYPE_SIGN (type)))
{
- if (TYPE_OVERFLOW_UNDEFINED (ctype))
- *strict_overflow_p = true;
+ *strict_overflow_p = true;
return fold_build2 (code, ctype, fold_convert (ctype, op0),
fold_convert (ctype,
const_binop (TRUNC_DIV_EXPR,
diff --git a/gcc/testsuite/gcc.dg/ubsan/pr108995.c b/gcc/testsuite/gcc.dg/ubsan/pr108995.c
new file mode 100644
index 00000000000..166825b2ef8
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/ubsan/pr108995.c
@@ -0,0 +1,18 @@
+/* { dg-do run { target int32 } } */
+/* { dg-shouldfail "ubsan" } */
+/* With optimization we constant fold and diagnose the overflow and do
+ not sanitize anything. */
+/* { dg-skip-if "" { *-*-* } { "*" } { ! "-O0" } } */
+/* { dg-options "-fsanitize=undefined -fno-sanitize-recover=undefined" } */
+
+int a;
+const int b = 44514;
+int *c = &a;
+
+int main ()
+{
+ *c = 65526 * b / 6;
+ return 0;
+}
+
+/* { dg-output "signed integer overflow: 44514 \\* 65526 cannot be represented in type 'int'" } */
--
2.35.3
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH] middle-end/108995 - avoid folding when sanitizing overflow
@ 2023-03-08 9:38 Richard Biener
0 siblings, 0 replies; 3+ messages in thread
From: Richard Biener @ 2023-03-08 9:38 UTC (permalink / raw)
To: gcc-patches; +Cc: Jakub Jelinek
The following plugs one place in extract_muldiv where it should avoid
folding when sanitizing overflow.
I'm unsure about the testcase, I didn't find any that tests for
a runtime sanitizer error ...
Bootstrapped and tested on x86_64-unknown-linux-gnu.
OK?
PR middle-end/108995
* fold-const.cc (extract_muldiv_1): Avoid folding
(CST * b) / CST2 when sanitizing overflow and we rely on
overflow being undefined.
* gcc.dg/ubsan/pr108995.c: New testcase.
---
gcc/fold-const.cc | 7 +++----
gcc/testsuite/gcc.dg/ubsan/pr108995.c | 15 +++++++++++++++
2 files changed, 18 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/ubsan/pr108995.c
diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc
index 99882ef820a..02a24c5fe65 100644
--- a/gcc/fold-const.cc
+++ b/gcc/fold-const.cc
@@ -7093,6 +7093,7 @@ extract_muldiv_1 (tree t, tree c, enum tree_code code, tree wide_type,
If we have an unsigned type, we cannot do this since it will change
the result if the original computation overflowed. */
if (TYPE_OVERFLOW_UNDEFINED (ctype)
+ && !TYPE_OVERFLOW_SANITIZED (ctype)
&& ((code == MULT_EXPR && tcode == EXACT_DIV_EXPR)
|| (tcode == MULT_EXPR
&& code != TRUNC_MOD_EXPR && code != CEIL_MOD_EXPR
@@ -7102,8 +7103,7 @@ extract_muldiv_1 (tree t, tree c, enum tree_code code, tree wide_type,
if (wi::multiple_of_p (wi::to_wide (op1), wi::to_wide (c),
TYPE_SIGN (type)))
{
- if (TYPE_OVERFLOW_UNDEFINED (ctype))
- *strict_overflow_p = true;
+ *strict_overflow_p = true;
return fold_build2 (tcode, ctype, fold_convert (ctype, op0),
fold_convert (ctype,
const_binop (TRUNC_DIV_EXPR,
@@ -7112,8 +7112,7 @@ extract_muldiv_1 (tree t, tree c, enum tree_code code, tree wide_type,
else if (wi::multiple_of_p (wi::to_wide (c), wi::to_wide (op1),
TYPE_SIGN (type)))
{
- if (TYPE_OVERFLOW_UNDEFINED (ctype))
- *strict_overflow_p = true;
+ *strict_overflow_p = true;
return fold_build2 (code, ctype, fold_convert (ctype, op0),
fold_convert (ctype,
const_binop (TRUNC_DIV_EXPR,
diff --git a/gcc/testsuite/gcc.dg/ubsan/pr108995.c b/gcc/testsuite/gcc.dg/ubsan/pr108995.c
new file mode 100644
index 00000000000..79a178c6751
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/ubsan/pr108995.c
@@ -0,0 +1,15 @@
+/* { dg-do run { xfail *-*-* } } */
+/* With optimization we constant fold and diagnose the overflow and do
+ not sanitize anything. */
+/* { dg-skip-if "" { *-*-* } { "*" } { ! "-O0" } } */
+/* { dg-options "-fsanitize=undefined -fno-sanitize-recover=undefined" } */
+
+int a;
+const int b = 44514;
+int *c = &a;
+
+int main ()
+{
+ *c = 65526 * b / 6;
+ return 0;
+}
--
2.35.3
^ permalink raw reply [flat|nested] 3+ messages in thread
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2023-03-09 13:10 ` [PATCH] middle-end/108995 - avoid folding when sanitizing overflow Jakub Jelinek
2023-03-09 13:29 ` Richard Biener
2023-03-08 9:38 Richard Biener
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