Add support for PSL assumptions, used in formal verification (#880)

* vhdl: make the parser understand PSL assume

* assume does not actually have report according to the spec. Just a property.

* add SPL assume to semantic analysis

* canonicalise PSL assume

* add assume to annotations

* add PSL assume to simulation code

* statement -> directive

* add assume to translation files

* update ticked24 testcase

* correctly parse assume

* add assume testcase

* refactor chunk of duplicated code

1 files changed, 30 insertions, 0 deletions

diff --git a/testsuite/gna/issue880/psl.ref b/testsuite/gna/issue880/psl.ref
new file mode 100644
index 000000000..5fd471f5d
--- /dev/null
+++ b/testsuite/gna/issue880/psl.ref
@@ -0,0 +1,30 @@
+{ "details" : [
+ { "directive": "assumption",
+   "name": ".psl(behav).a1",
+   "file": "psl.vhdl",
+   "line": 27,
+   "count": 0,
+   "status": "passed"},
+ { "directive": "assumption",
+   "name": ".psl(behav).a2",
+   "file": "psl.vhdl",
+   "line": 28,
+   "count": 0,
+   "status": "passed"},
+ { "directive": "cover",
+   "name": ".psl(behav).c1",
+   "file": "psl.vhdl",
+   "line": 29,
+   "count": 3,
+   "status": "covered"}],
+ "summary" : {
+  "assert": 0,
+  "assert-failure": 0,
+  "assert-pass": 0,
+  "assume": 2,
+  "assume-failure": 0,
+  "assume-pass": 2,
+  "cover": 1,
+  "cover-failure": 0,
+  "cover-pass": 1}
+}