interp: add testing for scanning for side effects

interp/testdata/scan.ll

@@ -0,0 +1,53 @@
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64--linux"
+
+define i64 @returnsConst() {
+  ret i64 0
+}
+
+define i64 @returnsArg(i64 %arg) {
+  ret i64 %arg
+}
+
+declare i64 @externalCall()
+
+define i64 @externalCallOnly() {
+  %result = call i64 @externalCall()
+  ret i64 0
+}
+
+define i64 @externalCallAndReturn() {
+  %result = call i64 @externalCall()
+  ret i64 %result
+}
+
+define i64 @externalCallBranch() {
+  %result = call i64 @externalCall()
+  %zero = icmp eq i64 %result, 0
+  br i1 %zero, label %if.then, label %if.done
+
+if.then:
+  ret i64 2
+
+if.done:
+  ret i64 4
+}
+
+@cleanGlobalInt = global i64 5
+define i64 @readCleanGlobal() {
+  %global = load i64, i64* @cleanGlobalInt
+  ret i64 %global
+}
+
+@dirtyGlobalInt = global i64 5
+define i64 @readDirtyGlobal() {
+  %global = load i64, i64* @dirtyGlobalInt
+  ret i64 %global
+}
+
+@functionPointer = global i64()* null
+define i64 @callFunctionPointer() {
+  %fp = load i64()*, i64()** @functionPointer
+  %result = call i64 %fp()
+  ret i64 %result
+}