Add doc for pmgen semioptional statement, Add pmgen changes to CHANGELOG

Signed-off-by: Clifford Wolf <clifford@clifford.at>

diff --git a/CHANGELOG b/CHANGELOG
index 638c3612174ca21580d98cc0d82718d7784348a9..cceb9fc9ff211f0e7e827eefe7c02008fead1007 100644 (file)
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -19,6 +19,7 @@ Yosys 0.9 .. Yosys 0.9-dev
     - Added automatic gzip compression (based on filename extension) for backends
     - Improve attribute and parameter encoding in JSON to avoid ambiguities between
       bit vectors and strings containing [01xz]*
+    - Improvements in pmgen: subpattern and recursive matches
 
 Yosys 0.8 .. Yosys 0.8-dev
 --------------------------

diff --git a/passes/pmgen/README.md b/passes/pmgen/README.md
index 4aa7de1623c658ce4fd62a361f246bfe2d638701..f92445a864b161b81e1f76ec94e9e20b9bbb79b0 100644 (file)
--- a/passes/pmgen/README.md
+++ b/passes/pmgen/README.md
@@ -175,6 +175,9 @@ explore the case where `mul` is set to `nullptr`. Without the `optional`
 statement a match may only be assigned nullptr when one of the `if` expressions
 evaluates to `false`.
 
+The `semioptional` statement marks matches that must match if at least one
+matching cell exists, but if no matching cell exists it is set to `nullptr`.
+
 Additional code
 ---------------