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* [gcc/devel/c++-modules] analyzer: fix pattern-test-2.c (PR 93291)
@ 2020-01-31 17:43 Nathan Sidwell
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From: Nathan Sidwell @ 2020-01-31 17:43 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:f89e844f9c589d1717248597641d25d81a4acb41
commit f89e844f9c589d1717248597641d25d81a4acb41
Author: David Malcolm <dmalcolm@redhat.com>
Date: Fri Jan 17 11:03:15 2020 -0500
analyzer: fix pattern-test-2.c (PR 93291)
Amongst the inputs to the analyzer state machines that can lead to state
transitions are conditions on CFG edges, such as a test for a pointer
being non-NULL.
These conditionals can be non-trivial to determine in the face of
optimization. For example, at -O2:
if (p == NULL || q == NULL)
is optimized on some targets (e.g. x86_64) to a bitwise-or:
_1 = p_5(D) == 0B;
_2 = q_6(D) == 0B;
_3 = _1 | _2;
if (_3 != 0)
goto <bb 4>; [51.12%]
else
goto <bb 3>; [48.88%]
but on other targets (e.g. powerpc64le) as control flow:
if (p_2(D) == 0B)
goto <bb 5>; [18.09%]
else
goto <bb 3>; [81.91%]
<bb 3> [local count: 879501929]:
if (q_3(D) == 0B)
goto <bb 5>; [30.95%]
else
goto <bb 4>; [69.05%]
region_model::add_any_constraints_from_ssa_def_stmt attempts to walk
SSA def chains to reconstruct the conditions that hold, so that
e.g. in the above case of bitwise-or, the state machine for
"p" can transition to the "known-null" state along the edge leading
to bb 3.
In gcc.dg/analyzer/pattern-test-2.c I attempted to write test coverage
for this, but the test fails on those targets for which the || is
expressed via control flow.
This patch rewrites the test to make explicit use of bitwise-or, and
adds coverage for bitwise-and for good measure.
gcc/testsuite/ChangeLog:
PR analyzer/93291
* gcc.dg/analyzer/pattern-test-2.c: Remove include of stdlib.h.
(test_2): Rewrite to explicitly perform a bitwise-or of two
boolean conditions.
(test_3): New function, to test bitwise-and.
Diff:
---
gcc/testsuite/ChangeLog | 8 +++++++
gcc/testsuite/gcc.dg/analyzer/pattern-test-2.c | 30 +++++++++++++++++++++++---
2 files changed, 35 insertions(+), 3 deletions(-)
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 4359aa1..56acbd9 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2020-01-27 David Malcolm <dmalcolm@redhat.com>
+
+ PR analyzer/93291
+ * gcc.dg/analyzer/pattern-test-2.c: Remove include of stdlib.h.
+ (test_2): Rewrite to explicitly perform a bitwise-or of two
+ boolean conditions.
+ (test_3): New function, to test bitwise-and.
+
2020-01-27 Richard Sandiford <richard.sandiford@arm.com>
PR testsuite/71727
diff --git a/gcc/testsuite/gcc.dg/analyzer/pattern-test-2.c b/gcc/testsuite/gcc.dg/analyzer/pattern-test-2.c
index ffc06a2..f5424f5 100644
--- a/gcc/testsuite/gcc.dg/analyzer/pattern-test-2.c
+++ b/gcc/testsuite/gcc.dg/analyzer/pattern-test-2.c
@@ -1,8 +1,6 @@
/* { dg-additional-options "-fanalyzer-checker=pattern-test -O2" } */
// TODO: run this at every optimization level
-#include <stdlib.h>
-
extern void foo(void *);
extern void bar(void *);
@@ -18,12 +16,38 @@ void test1(void *ptr)
void test_2 (void *p, void *q)
{
- if (p == NULL || q == NULL) /* { dg-line cond_2 } */
+ _Bool tmp1 = p == 0;
+ _Bool tmp2 = q == 0;
+ _Bool tmp = tmp1 | tmp2;
+
+ /* Verify that we can detect the implied conditions on p and q here. */
+ if (tmp) /* { dg-line cond_2 } */
return;
foo(p);
+ /* { dg-warning "pattern match on 'tmp1 == 0'" "tmp1 == 0" { target *-*-* } cond_2 } */
+ /* { dg-warning "pattern match on 'tmp2 == 0'" "tmp2 == 0" { target *-*-* } cond_2 } */
/* { dg-warning "pattern match on '<unknown> == 0'" "<unknown> == 0" { target *-*-* } cond_2 } */
/* { dg-warning "pattern match on '<unknown> != 0'" "<unknown> != 0" { target *-*-* } cond_2 } */
/* { dg-warning "pattern match on 'p != 0'" "p != 0" { target *-*-* } cond_2 } */
/* { dg-warning "pattern match on 'q != 0'" "q != 0" { target *-*-* } cond_2 } */
}
+
+void test_3 (void *p, void *q)
+{
+ _Bool tmp1 = p == 0;
+ _Bool tmp2 = q == 0;
+ _Bool tmp = tmp1 & tmp2;
+
+ /* Verify that we can detect the implied conditions on p and q here. */
+ if (tmp) /* { dg-line cond_3 } */
+ return;
+ foo(p);
+
+ /* { dg-warning "pattern match on 'tmp1 != 0'" "tmp1 != 0" { target *-*-* } cond_3 } */
+ /* { dg-warning "pattern match on 'tmp2 != 0'" "tmp2 != 0" { target *-*-* } cond_3 } */
+ /* { dg-warning "pattern match on '<unknown> == 0'" "<unknown> == 0" { target *-*-* } cond_3 } */
+ /* { dg-warning "pattern match on '<unknown> != 0'" "<unknown> != 0" { target *-*-* } cond_3 } */
+ /* { dg-warning "pattern match on 'p == 0'" "p == 0" { target *-*-* } cond_3 } */
+ /* { dg-warning "pattern match on 'q == 0'" "q == 0" { target *-*-* } cond_3 } */
+}
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