[gcc r10-6496] analyzer: fix reproducer for PR 93375

[gcc r10-6496] analyzer: fix reproducer for PR 93375

[David Malcolm]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="us-ascii", Size: 2929 bytes --]

https://gcc.gnu.org/g:13f5b93e6453d121abc15c718dfcc588aca976c3

commit r10-6496-g13f5b93e6453d121abc15c718dfcc588aca976c3
Author: David Malcolm <dmalcolm@redhat.com>
Date:   Thu Feb 6 14:17:48 2020 -0500

    analyzer: fix reproducer for PR 93375
    
    Reproducing the ICE in PR analyzer/93375 required some kind of
    analyzer diagnostic occurring after a call with fewer arguments
    than required by the callee.
    
    The testcase used __builtin_memcpy with a NULL argument for this.
    
    On x86_64-pc-linux-gnu this happened to be already optimized into:
      _4 = MEM <unsigned int> [(char * {ref-all})0B];
      MEM <unsigned int> [(char * {ref-all})rl_1] = _4;
    by the time of the analyzer pass, leading to the diagnostic in question
    being:
      warning: dereference of NULL ‘rl’ [CWE-690] [-Wanalyzer-null-dereference]
    
    On other targets e.g. arm-unknown-linux-gnueabi, the builtin isn't
    optimized at the time of the analyzer pass, leading to this diagnostic
    instead:
      warning: use of NULL ‘rl’ where non-null expected [CWE-690] [-Wanalyzer-null-argument]
      <built-in>: note: argument 1 of ‘__builtin_memcpy’ must be non-null
    
    This patch fixes the test case by using a custom function marked as
    nonnull.  I manually verified that it still reproduces the ICE if the
    patch for the PR is reverted.
    
    gcc/testsuite/ChangeLog:
    	PR analyzer/93375
    	* gcc.dg/analyzer/pr93375.c: Rework test case to avoid per-target
    	differences in how __builtin_memcpy has been optimized at the time
    	the analyzer runs.

Diff:
---
 gcc/testsuite/ChangeLog                 | 7 +++++++
 gcc/testsuite/gcc.dg/analyzer/pr93375.c | 4 +++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index f6f12dd..a6fbf5b 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,12 @@
 2020-02-06  David Malcolm  <dmalcolm@redhat.com>
 
+	PR analyzer/93375
+	* gcc.dg/analyzer/pr93375.c: Rework test case to avoid per-target
+	differences in how __builtin_memcpy has been optimized at the time
+	the analyzer runs.
+
+2020-02-06  David Malcolm  <dmalcolm@redhat.com>
+
 	* gcc.dg/analyzer/torture/intptr_t.c: New test.
 
 2020-02-06  Segher Boessenkool  <segher@kernel.crashing.org>
diff --git a/gcc/testsuite/gcc.dg/analyzer/pr93375.c b/gcc/testsuite/gcc.dg/analyzer/pr93375.c
index 93a3e87..f610854 100644
--- a/gcc/testsuite/gcc.dg/analyzer/pr93375.c
+++ b/gcc/testsuite/gcc.dg/analyzer/pr93375.c
@@ -1,5 +1,7 @@
 /* { dg-additional-options "-Wno-implicit-int" } */
 
+extern void foo (void *) __attribute__((nonnull));
+
 void
 en (jm)
 {
@@ -11,5 +13,5 @@ p2 ()
   char *rl = 0;
 
   en ();
-  __builtin_memcpy (rl, 0, sizeof (0)); /* { dg-warning "dereference of NULL" } */
+  foo (rl); /* { dg-warning "use of NULL 'rl' where non-null expected" } */
 }