When a function is declared const (even though it technically
accesses memory), ipa-modref discovering pureness shouldn't end
up suggesting that attribute. The following thus exempts
'const' functions from ipa_make_function_pure handling.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
PR ipa/105676
* ipa-pure-const.cc (ipa_make_function_pure): Skip also
for functions already being const.
* gcc.dg/pr105676.c: New testcase.
---
gcc/ipa-pure-const.cc | 5 +++--
gcc/testsuite/gcc.dg/pr105676.c | 14 ++++++++++++++
2 files changed, 17 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/pr105676.c
diff --git a/gcc/ipa-pure-const.cc b/gcc/ipa-pure-const.cc
index 572a6da274f..0b748eee0ee 100644
--- a/gcc/ipa-pure-const.cc
+++ b/gcc/ipa-pure-const.cc
@@ -1526,8 +1526,9 @@ ipa_make_function_pure (struct cgraph_node *node, bool
looping, bool local)
{
bool cdtor = false;
- if (DECL_PURE_P (node->decl)
- && (looping || !DECL_LOOPING_CONST_OR_PURE_P (node->decl)))
+ if (TREE_READONLY (node->decl)
+ || (DECL_PURE_P (node->decl)
+ && (looping || !DECL_LOOPING_CONST_OR_PURE_P (node->decl))))
return false;
warn_function_pure (node->decl, !looping);
if (local && skip_function_for_local_pure_const (node))
diff --git a/gcc/testsuite/gcc.dg/pr105676.c b/gcc/testsuite/gcc.dg/pr105676.c
new file mode 100644
index 00000000000..077fc18a17f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr105676.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -Wsuggest-attribute=pure" } */
+
+__attribute__((const))
+extern int do_expensive_calculation(void);
+
+__attribute__((const))
+int getval(void) /* { dg-bogus "candidate for attribute" } */
+{
+ static int cache = -1;
+ if (cache == -1)
+ cache = do_expensive_calculation();
+ return cache;
+}
--
2.35.3
