Hi,
this patch fixes polymorphic call analysis in thunks. Unlike normal
methods, thunks take THIS pointer offsetted by a known constant. This
needs t be compensated for when calculating address of outer type.
Bootstrapped/regtested x86_64-linux, also tested with Firefox where this
bug trigger misoptimization in spellchecker. I plan to backport it to
release branches soon.
Honza
PR ipa/88561
* ipa-polymorphic-call.c
(ipa_polymorphic_call_context::ipa_polymorphic_call_context): Handle
arguments of thunks correctly.
(ipa_polymorphic_call_context::get_dynamic_context): Be ready for
NULL instance pinter.
* lto-cgraph.c (lto_output_node): Always stream thunk info.
* g++.dg/tree-prof/devirt.C: New testcase.
Index: ipa-polymorphic-call.c
===================================================================
--- ipa-polymorphic-call.c (revision 267325)
+++ ipa-polymorphic-call.c (working copy)
@@ -995,9 +995,22 @@ ipa_polymorphic_call_context::ipa_polymo
{
outer_type
= TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (base_pointer)));
+ cgraph_node *node = cgraph_node::get (current_function_decl);
gcc_assert (TREE_CODE (outer_type) == RECORD_TYPE
|| TREE_CODE (outer_type) == UNION_TYPE);
+ /* Handle the case we inlined into a thunk. In this case
+ thunk has THIS pointer of type bar, but it really receives
+ address to its base type foo which sits in bar at
+ 0-thunk.fixed_offset. It starts with code that adds
+ think.fixed_offset to the pointer to compensate for this.
+
+ Because we walked all the way to the begining of thunk, we now
+ see pointer &bar-thunk.fixed_offset and need to compensate
+ for it. */
+ if (node->thunk.fixed_offset)
+ offset -= node->thunk.fixed_offset * BITS_PER_UNIT;
+
/* Dynamic casting has possibly upcasted the type
in the hiearchy. In this case outer type is less
informative than inner type and we should forget
@@ -1005,7 +1018,11 @@ ipa_polymorphic_call_context::ipa_polymo
if ((otr_type
&& !contains_type_p (outer_type, offset,
otr_type))
- || !contains_polymorphic_type_p (outer_type))
+ || !contains_polymorphic_type_p (outer_type)
+ /* If we compile thunk with virtual offset, the THIS pointer
+ is adjusted by unknown value. We can't thus use outer info
+ at all. */
+ || node->thunk.virtual_offset_p)
{
outer_type = NULL;
if (instance)
@@ -1030,7 +1047,15 @@ ipa_polymorphic_call_context::ipa_polymo
maybe_in_construction = false;
}
if (instance)
- *instance = base_pointer;
+ {
+ /* If method is expanded thunk, we need to apply thunk offset
+ to instance pointer. */
+ if (node->thunk.virtual_offset_p
+ || node->thunk.fixed_offset)
+ *instance = NULL;
+ else
+ *instance = base_pointer;
+ }
return;
}
/* Non-PODs passed by value are really passed by invisible
@@ -1547,6 +1572,9 @@ ipa_polymorphic_call_context::get_dynami
HOST_WIDE_INT instance_offset = offset;
tree instance_outer_type = outer_type;
+ if (!instance)
+ return false;
+
if (otr_type)
otr_type = TYPE_MAIN_VARIANT (otr_type);
Index: lto-cgraph.c
===================================================================
--- lto-cgraph.c (revision 267325)
+++ lto-cgraph.c (working copy)
@@ -547,7 +547,11 @@ lto_output_node (struct lto_simple_outpu
streamer_write_bitpack (&bp);
streamer_write_data_stream (ob->main_stream, section, strlen (section) + 1);
- if (node->thunk.thunk_p)
+ /* Stream thunk info always because we use it in
+ ipa_polymorphic_call_context::ipa_polymorphic_call_context
+ to properly interpret THIS pointers for thunks that has been converted
+ to Gimple. */
+ if (node->definition)
{
streamer_write_uhwi_stream
(ob->main_stream,
@@ -1295,7 +1299,7 @@ input_node (struct lto_file_decl_data *f
if (section)
node->set_section_for_node (section);
- if (node->thunk.thunk_p)
+ if (node->definition)
{
int type = streamer_read_uhwi (ib);
HOST_WIDE_INT fixed_offset = streamer_read_uhwi (ib);
Index: testsuite/g++.dg/tree-prof/devirt.C
===================================================================
--- testsuite/g++.dg/tree-prof/devirt.C (nonexistent)
+++ testsuite/g++.dg/tree-prof/devirt.C (working copy)
@@ -0,0 +1,123 @@
+/* { dg-options "-O3 -fdump-tree-dom3" } */
+struct nsISupports
+{
+ virtual int QueryInterface (const int &aIID, void **aInstancePtr) = 0;
+ virtual __attribute__((noinline, noclone)) unsigned AddRef (void) = 0;
+ virtual unsigned Release (void) = 0;
+};
+
+struct nsIObserver : public nsISupports
+{
+ virtual int Observe (nsISupports * aSubject, const char *aTopic, const
unsigned short *aData) = 0;
+};
+
+struct nsISupportsWeakReference : public nsISupports
+{
+ virtual int GetWeakReference (void **_retval) = 0;
+};
+
+struct nsSupportsWeakReference : public nsISupportsWeakReference
+{
+ nsSupportsWeakReference () : mProxy (0) {}
+ virtual int GetWeakReference (void **_retval) override { return 0; }
+ ~nsSupportsWeakReference () {}
+ void NoticeProxyDestruction () { mProxy = nullptr; }
+ void *mProxy;
+ void ClearWeakReferences ();
+ bool HasWeakReferences () const { return !!mProxy; }
+};
+
+struct mozIPersonalDictionary : public nsISupports
+{
+ virtual int Load (void) = 0;
+ virtual int Save (void) = 0;
+ virtual int GetWordList (void **aWordList) = 0;
+ virtual int Check (const int &word, bool * _retval) = 0;
+ virtual int AddWord (const int &word) = 0;
+ virtual int RemoveWord (const int &word) = 0;
+ virtual int IgnoreWord (const int &word) = 0;
+ virtual int EndSession (void) = 0;
+};
+
+struct mozPersonalDictionary final
+ : public mozIPersonalDictionary, public nsIObserver, public
nsSupportsWeakReference
+{
+ virtual int QueryInterface (const int &aIID, void **aInstancePtr) override;
+ virtual __attribute__((noinline, noclone)) unsigned AddRef (void) override;
+ virtual unsigned Release (void) override;
+ unsigned long mRefCnt;
+ virtual int Load (void) override { return 0; }
+ virtual int Save (void) override { return 0; }
+ virtual int GetWordList (void **aWordList) override { return 0; }
+ virtual int Check (const int &word, bool * _retval) override { return 0; }
+ virtual int AddWord (const int &word) override { return 0; }
+ virtual int RemoveWord (const int &word) override { return 0; }
+ virtual int IgnoreWord (const int &word) override { return 0; }
+ virtual int EndSession (void) override { return 0; }
+ virtual int Observe (nsISupports * aSubject, const char *aTopic, const
unsigned short *aData) override { return 0; }
+ mozPersonalDictionary () : mRefCnt(0) {}
+ int Init () { return 0; }
+ virtual ~mozPersonalDictionary () {}
+ bool mIsLoaded;
+ bool mSavePending;
+ void *mFile;
+ char mMonitor[96];
+ char mMonitorSave[96];
+ char mDictionaryTable[32];
+ char mIgnoreTable[32];
+};
+
+unsigned
+mozPersonalDictionary::AddRef (void)
+{
+ unsigned count = ++mRefCnt;
+ return count;
+}
+
+unsigned
+mozPersonalDictionary::Release (void)
+{
+ unsigned count = --mRefCnt;
+ if (count == 0)
+ {
+ mRefCnt = 1;
+ delete (this);
+ return 0;
+ }
+ return count;
+}
+
+int
+mozPersonalDictionary::QueryInterface (const int &aIID, void **aInstancePtr)
+{
+ nsISupports *foundInterface;
+ if (aIID == 122)
+ foundInterface = static_cast <mozIPersonalDictionary *>(this);
+ else
+ foundInterface = static_cast <nsISupportsWeakReference *>(this);
+ int status;
+ foundInterface->AddRef ();
+ *aInstancePtr = foundInterface;
+ return status;
+}
+
+__attribute__((noipa)) int
+foo (nsISupports *p, const int &i)
+{
+ void *q;
+ return p->QueryInterface (i, &q);
+}
+
+int
+main ()
+{
+ mozPersonalDictionary m;
+ int j = 123;
+ for (int i = 0; i < 100000; i++)
+ foo (static_cast <nsISupportsWeakReference *>(&m), j);
+ if (m.mRefCnt != 100000)
+ __builtin_abort ();
+}
+
+/* { dg-final-use-not-autofdo { scan-ipa-dump-times 3 "folding virtual
function call to virtual unsigned int mozPersonalDictionary::_ZThn16" "dom3" }
} */
+/* { dg-final-use-not-autofdo { scan-ipa-dump-times 3 "folding virtual
function call to virtual unsigned int mozPersonalDictionary::AddRef" "dom3" } }
*/
