From: Martin Jambor <mjambor@suse.cz>
Date: Wed, 7 Oct 2020 12:12:49 +0000 (+0200)
Subject: ipa-prop: Fix multiple-target speculation resolution
X-Git-Tag: releases/gcc-10.3.0~767
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a9e64bb6d0801f29d65f357f90e6d7a2daeb6ca9;p=thirdparty%2Fgcc.git

ipa-prop: Fix multiple-target speculation resolution

As the FIXME which this patch removes states, the current code does
not work when a call with multiple speculative targets gets resolved
through parameter tracking during inlining - it feeds the inliner an
edge it has already dealt with.  The patch makes the code which should
prevent it aware of the possibility that that speculation can have
more than one target now.

gcc/ChangeLog:

2020-09-30  Martin Jambor  <mjambor@suse.cz>

	PR ipa/96394
	* ipa-prop.c (update_indirect_edges_after_inlining): Do not add
	resolved speculation edges to vector of new direct edges even in
	presence of multiple speculative direct edges for a single call.

gcc/testsuite/ChangeLog:

2020-09-30  Martin Jambor  <mjambor@suse.cz>

	PR ipa/96394
	* gcc.dg/tree-prof/pr96394.c: New test.

(cherry picked from commit e089e43365f7f2a90979e2316aea25d44823f5a3)
---

diff --git a/gcc/ipa-prop.c b/gcc/ipa-prop.c
index 0d9f0a8ab8d8..114a4ee21270 100644
--- a/gcc/ipa-prop.c
+++ b/gcc/ipa-prop.c
@@ -3788,11 +3788,13 @@ update_indirect_edges_after_inlining (struct cgraph_edge *cs,
 
       param_index = ici->param_index;
       jfunc = ipa_get_ith_jump_func (top, param_index);
-      cgraph_node *spec_target = NULL;
 
-      /* FIXME: This may need updating for multiple calls.  */
+      auto_vec<cgraph_node *, 4> spec_targets;
       if (ie->speculative)
-	spec_target = ie->first_speculative_call_target ()->callee;
+	for (cgraph_edge *direct = ie->first_speculative_call_target ();
+	     direct;
+	     direct = direct->next_speculative_call_target ())
+	  spec_targets.safe_push (direct->callee);
 
       if (!opt_for_fn (node->decl, flag_indirect_inlining))
 	new_direct_edge = NULL;
@@ -3815,7 +3817,7 @@ update_indirect_edges_after_inlining (struct cgraph_edge *cs,
 
       /* If speculation was removed, then we need to do nothing.  */
       if (new_direct_edge && new_direct_edge != ie
-	  && new_direct_edge->callee == spec_target)
+	  && spec_targets.contains (new_direct_edge->callee))
 	{
 	  new_direct_edge->indirect_inlining_edge = 1;
 	  top = IPA_EDGE_REF (cs);
diff --git a/gcc/testsuite/gcc.dg/tree-prof/pr96394.c b/gcc/testsuite/gcc.dg/tree-prof/pr96394.c
new file mode 100644
index 000000000000..4280182a7c30
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-prof/pr96394.c
@@ -0,0 +1,64 @@
+/* PR ipa/96394 */
+/* { dg-options "-O2" } */
+
+typedef struct _entry {
+    int has_next;
+    int next_ix;
+    int count;
+} entry;
+
+extern entry table[];
+
+void *
+__attribute__((noipa))
+PyErr_Format(entry * e){ return 0; }
+
+void ae(entry *);
+int h(entry *);
+int ap(entry *);
+int ag(entry *);
+
+int ag(entry *j) {
+  if (j->has_next)
+    h(&table[j->next_ix]);
+  return 0;
+}
+static int ai(entry *j, int k(entry *), int l, int m) {
+  int am = 1;
+  int ab;
+
+  /* k is either 'h' or 'ap': 50%/50% */
+  ab = k(j);
+
+  /* loop never gets executed on real data */
+  for (; j->count >= 2; am += 2)
+    if (l) {
+      entry *i = &table[am + m];
+      PyErr_Format(i);
+    }
+  return ab;
+}
+void
+__attribute__((noipa))
+bug() {
+  h(table);
+  h(table);
+}
+int h(entry *j) { return ai(j, ap, 4, 5); }
+int ap(entry *j) { return ai(j, ag, 14, 4); }
+
+int main(void)
+{
+    bug();
+}
+
+entry table[2] = {
+    { .has_next = 1
+    , .next_ix  = 1
+    , .count    = 0
+    },
+    { .has_next = 0
+    , .next_ix  = 0
+    , .count    = 0
+    },
+};