OP_LOADs were ignored by kill_instruction() but there are two cases
were something can or must be done:
1) if the is not a volatile one, it is free of side-effects and can thus
be optimized away like others instructions.
2) if force-killed then we need to adjust the usage of its operand.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
simplify.c | 6 ++++++
validation/kill-load.c | 17 +++++++++++++++++
2 files changed, 23 insertions(+)
create mode 100644 validation/kill-load.c
diff --git a/simplify.c b/simplify.c
index b80d05b87..a27f6a33a 100644
--- a/simplify.c
+++ b/simplify.c
@@ -249,6 +249,12 @@ void kill_insn(struct instruction *insn, int force)
kill_use(&insn->func);
break;
+ case OP_LOAD:
+ if (!force && insn->type->ctype.modifiers & MOD_VOLATILE)
+ return;
+ kill_use(&insn->src);
+ break;
+
case OP_ENTRY:
/* ignore */
return;
diff --git a/validation/kill-load.c b/validation/kill-load.c
new file mode 100644
index 000000000..45fb83e4b
--- /dev/null
+++ b/validation/kill-load.c
@@ -0,0 +1,17 @@
+int keep(volatile int *p) { return *p && 0; }
+int kill(int *p, int i) { return *p && 0; }
+void ind(volatile int *p,int i) { int v = i++; if (i && 0) p[v]; }
+
+
+/*
+ * check-name: kill-load
+ * check-command: test-linearize -Wno-decl $file
+ * check-description:
+ * Check that loads are optimized away but only
+ * when needed:
+ * - non-volatile
+ * - bb unreachable.
+ *
+ * check-output-ignore
+ * check-output-pattern-1-times: load\\.
+ */
--
2.11.0
--
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
