cmd/compile: add ellipsis syntax for op-only rewrite rules
This change introduces a new syntax for rewrite rules
that only change a Value's Op. See #36380 for more discussion.
Updating rewrite rules to use ellipses will happen
in follow-up CLs.
Change-Id: I8c56e85de24607579d79729575c89ca80805ba5c
Reviewed-on: https://go-review.googlesource.com/c/go/+/213898
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
diff --git a/src/cmd/compile/internal/ssa/gen/rulegen.go b/src/cmd/compile/internal/ssa/gen/rulegen.go
index 5a22280..c39ded4 100644
--- a/src/cmd/compile/internal/ssa/gen/rulegen.go
+++ b/src/cmd/compile/internal/ssa/gen/rulegen.go
@@ -176,6 +176,15 @@
sw := &Switch{expr: exprf("v.Op")}
for _, op := range ops {
+ eop, ok := parseEllipsisRules(oprules[op], arch)
+ if ok {
+ swc := &Case{expr: exprf(op)}
+ swc.add(stmtf("v.Op = %s", eop))
+ swc.add(stmtf("return true"))
+ sw.add(swc)
+ continue
+ }
+
var ors []string
for chunk := 0; chunk < len(oprules[op]); chunk += chunkSize {
ors = append(ors, fmt.Sprintf("rewriteValue%s%s_%s_%d(v)", arch.name, suff, op, chunk))
@@ -192,6 +201,11 @@
// because it is too big for some compilers.
for _, op := range ops {
rules := oprules[op]
+ _, ok := parseEllipsisRules(oprules[op], arch)
+ if ok {
+ continue
+ }
+
// rr is kept between chunks, so that a following chunk checks
// that the previous one ended with a rule that wasn't
// unconditional.
@@ -1240,7 +1254,7 @@
if x.name != s {
return false
}
- if x.argLength != -1 && int(x.argLength) != len(args) {
+ if x.argLength != -1 && int(x.argLength) != len(args) && (len(args) != 1 || args[0] != "...") {
if strict {
return false
}
@@ -1507,3 +1521,28 @@
}
return s.String()
}
+
+func parseEllipsisRules(rules []Rule, arch arch) (newop string, ok bool) {
+ if len(rules) != 1 {
+ return "", false
+ }
+ rule := rules[0]
+ match, cond, result := rule.parse()
+ if cond != "" || !isEllipsisValue(match) || !isEllipsisValue(result) {
+ return "", false
+ }
+ op, oparch, _, _, _, _ := parseValue(result, arch, rule.loc)
+ return fmt.Sprintf("Op%s%s", oparch, op.name), true
+}
+
+// isEllipsisValue reports whether s is of the form (OpX ...).
+func isEllipsisValue(s string) bool {
+ if len(s) < 2 || s[0] != '(' || s[len(s)-1] != ')' {
+ return false
+ }
+ c := split(s[1 : len(s)-1])
+ if len(c) != 2 || c[1] != "..." {
+ return false
+ }
+ return true
+}
