[PATCH 1/4] volatile loads must not be simplified

[Luc Van Oostenryck <luc.vanoostenryck@gmail.com>]

memops.c:simplify_loads() tries to simplify all loads,
even volatile ones.
For example, on the following code:
	static int foo(volatile int *a, int v)
	{
		*a = v;
		return *a;
	}

test-linearize returns something like:
	foo:
		store.32    %arg2 -> 0[%arg1]
		ret.32      %arg2

while the correct output is more like:
	foo:
		store.32    %arg2 -> 0[%arg1]
		load.32     %r5 <- 0[%arg1]
		ret.32      %r5

The fix is to simply ignore loads with the 'volatile' modifier.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
---
 memops.c                     |  3 +++
 validation/memops-volatile.c | 21 +++++++++++++++++++++
 2 files changed, 24 insertions(+)
 create mode 100644 validation/memops-volatile.c

diff --git a/memops.c b/memops.c
index 45bd3401..6dac1f57 100644
--- a/memops.c
+++ b/memops.c
@@ -99,6 +99,9 @@ static void simplify_loads(struct basic_block *bb)
 			/* Check for illegal offsets.. */
 			check_access(insn);
 
+			if (insn->type->ctype.modifiers & MOD_VOLATILE)
+				continue;
+
 			RECURSE_PTR_REVERSE(insn, dom) {
 				int dominance;
 				if (!dom->bb)
diff --git a/validation/memops-volatile.c b/validation/memops-volatile.c
new file mode 100644
index 00000000..0f3e12ad
--- /dev/null
+++ b/validation/memops-volatile.c
@@ -0,0 +1,21 @@
+static int foo(volatile int *a, int v)
+{
+	*a = v;
+	return *a;
+}
+
+/*
+ * check-name: memops-volatile
+ * check-command: test-linearize $file
+ *
+ * check-output-start
+foo:
+.L0:
+	<entry-point>
+	store.32    %arg2 -> 0[%arg1]
+	load.32     %r5 <- 0[%arg1]
+	ret.32      %r5
+
+
+ * check-output-end
+ */
-- 
2.11.0