Patch 11b1a83b1 solved an issue with dangling PSEUDO_PHI
by killing it's use after a branch rewrite.
However, the change didn't took in account the fact that,
even after the branch rewrite, some other paths may exist
where this pseudo was needed.
Fix this by cheking that no such path exist before killing
the (usage of the) pseudo.
Fixes: 11b1a83b1 "fix OP_PHI usage in try_to_simplify_bb()"
Reported-by: Dibyendu Majumdar <mobile@xxxxxxxxxxxxxxx>
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
flow.c | 35 ++++++++++++++++++++++++++++++++++-
validation/kill-phi-ttsbb2.c | 40 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 74 insertions(+), 1 deletion(-)
create mode 100644 validation/kill-phi-ttsbb2.c
diff --git a/flow.c b/flow.c
index a5332203f..c12bc0716 100644
--- a/flow.c
+++ b/flow.c
@@ -79,6 +79,39 @@ static int bb_depends_on(struct basic_block *target, struct basic_block *src)
return 0;
}
+/*
+ * Return 1 if 'pseudo' is needed in some parent of 'bb'.
+ * Need liveness info.
+ */
+static int needed_phisrc(struct instruction *phi, struct basic_block *curr, unsigned long generation)
+{
+ pseudo_t target = phi->target;
+ struct basic_block *bb;
+ int rc = 0;
+
+ curr->generation = generation;
+ FOR_EACH_PTR(curr->children, bb) {
+ if (bb->generation == generation)
+ continue;
+ if (bb == phi->bb)
+ continue;
+ if (pseudo_in_list(bb->defines, target)) {
+ continue;
+ }
+ if (pseudo_in_list(bb->needs, target)) {
+ rc = 1;
+ goto ret;
+ }
+ rc = needed_phisrc(phi, bb, generation);
+ if (rc)
+ goto ret;
+
+ } END_FOR_EACH_PTR(bb);
+
+ret:
+ return rc;
+}
+
/*
* When we reach here, we have:
* - a basic block that ends in a conditional branch and
@@ -121,7 +154,7 @@ static int try_to_simplify_bb(struct basic_block *bb, struct instruction *first,
continue;
changed |= rewrite_branch(source, &br->bb_true, bb, target);
changed |= rewrite_branch(source, &br->bb_false, bb, target);
- if (changed)
+ if (changed && !needed_phisrc(first, source, ++bb_generation))
kill_use(THIS_ADDRESS(phi));
} END_FOR_EACH_PTR(phi);
return changed;
diff --git a/validation/kill-phi-ttsbb2.c b/validation/kill-phi-ttsbb2.c
new file mode 100644
index 000000000..c7d89aa0e
--- /dev/null
+++ b/validation/kill-phi-ttsbb2.c
@@ -0,0 +1,40 @@
+extern int error(int);
+
+int foo(int perr);
+int foo(int perr)
+{
+ int err = 0;
+ int rc = 0;
+ int j = 0;
+ int i = 1;
+
+ i && j++;
+
+ i-- && j;
+
+ i && j--;
+
+ if (j != 1) {
+ err = 1;
+ if (perr)
+ error(1);
+ }
+
+ if (err != 0)
+ rc = 1;
+
+ return rc;
+}
+
+/*
+ * check-name: kill-phi-ttsbb2
+ * check-description:
+ * Verify if OP_PHI usage is adjusted after successful try_to_simplify_bb()
+ * check-warning: this test is sensitive to details of code generation
+ * with proper bb packing (taking care of phi-nodes) it
+ * will be optimized away and test nothing. You have been warned.
+ * check-command: test-linearize $file
+ * check-output-ignore
+ *
+ * check-output-excludes: VOID
+ */
--
2.12.0
--
To unsubscribe from this list: send the line "unsubscribe linux-sparse" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
