analyzer: fix -Wanalyzer-allocation-size false -ve on alloca [PR108616]

gcc/analyzer/ChangeLog:
	PR analyzer/108616
	* pending-diagnostic.cc (fixup_location_in_macro_p): Add "alloca"
	to macros that we shouldn't unwind inside.

gcc/testsuite/ChangeLog:
	PR analyzer/108616
	* gcc.dg/analyzer/allocation-size-multiline-3.c: New test.
	* gcc.dg/analyzer/test-alloca.h: New test.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>

diff --git a/gcc/analyzer/pending-diagnostic.cc b/gcc/analyzer/pending-diagnostic.cc
index 79e6c5528ebcd8ba54db35bbad2bf701c294aced..e36ed4fd9c1f9ea96f4c42811b252b99cb99f9ed 100644 (file)
--- a/gcc/analyzer/pending-diagnostic.cc
+++ b/gcc/analyzer/pending-diagnostic.cc
@@ -139,6 +139,12 @@ static bool
 fixup_location_in_macro_p (cpp_hashnode *macro)
 {
   ht_identifier ident = macro->ident;
+
+  /* Don't unwind inside "alloca" macro, so that we don't suppress warnings
+     from it (due to being in system headers).  */
+  if (ht_ident_eq (ident, "alloca"))
+    return true;
+
   /* Don't unwind inside <stdarg.h> macros, so that we don't suppress warnings
      from them (due to being in system headers).  */
   if (ht_ident_eq (ident, "va_start")

diff --git a/gcc/testsuite/gcc.dg/analyzer/allocation-size-multiline-3.c b/gcc/testsuite/gcc.dg/analyzer/allocation-size-multiline-3.c
new file mode 100644 (file)
index 0000000..e27364a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/allocation-size-multiline-3.c
@@ -0,0 +1,44 @@
+/* Verify that we warn for incorrect uses of "alloca" (which may be in a 
+   macro in a system header), and that the output looks correct.  */
+
+/* { dg-additional-options "-fdiagnostics-path-format=inline-events -fdiagnostics-show-caret -fanalyzer-fine-grained" } */
+/* { dg-require-effective-target alloca } */
+
+#include <stdint.h>
+#include "test-alloca.h"
+
+void test_constant_99 (void)
+{
+  int32_t *ptr = alloca (99); /* { dg-warning "allocated buffer size is not a multiple of the pointee's size" } */
+}
+
+/* { dg-begin-multiline-output "" }
+   int32_t *ptr = alloca (99);
+                  ^~~~~~
+  'test_constant_99': events 1-2
+    |
+    |   int32_t *ptr = alloca (99);
+    |                  ^~~~~~
+    |                  |
+    |                  (1) allocated 99 bytes here
+    |                  (2) assigned to 'int32_t *' {aka 'int *'} here; 'sizeof (int32_t {aka int})' is '4'
+    |
+   { dg-end-multiline-output "" } */
+
+void test_symbolic (int n)
+{
+  int32_t *ptr = alloca (n * 2); /* { dg-warning "allocated buffer size is not a multiple of the pointee's size" } */
+}
+
+/* { dg-begin-multiline-output "" }
+   int32_t *ptr = alloca (n * 2);
+                  ^~~~~~
+  'test_symbolic': events 1-2
+    |
+    |   int32_t *ptr = alloca (n * 2);
+    |                  ^~~~~~
+    |                  |
+    |                  (1) allocated 'n * 2' bytes here
+    |                  (2) assigned to 'int32_t *' {aka 'int *'} here; 'sizeof (int32_t {aka int})' is '4'
+    |
+   { dg-end-multiline-output "" } */

diff --git a/gcc/testsuite/gcc.dg/analyzer/test-alloca.h b/gcc/testsuite/gcc.dg/analyzer/test-alloca.h
new file mode 100644 (file)
index 0000000..f4045f9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/test-alloca.h
@@ -0,0 +1,3 @@
+#pragma GCC system_header
+
+#define alloca(X) __builtin_alloca(X)