1 files changed, 81 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/ssa/cache.go b/src/cmd/compile/internal/ssa/cache.go
new file mode 100644
index 0000000..dbec2e1
--- /dev/null
+++ b/src/cmd/compile/internal/ssa/cache.go
@@ -0,0 +1,81 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+import (
+	"cmd/internal/obj"
+	"sort"
+)
+
+// A Cache holds reusable compiler state.
+// It is intended to be re-used for multiple Func compilations.
+type Cache struct {
+	// Storage for low-numbered values and blocks.
+	values [2000]Value
+	blocks [200]Block
+	locs   [2000]Location
+
+	// Reusable stackAllocState.
+	// See stackalloc.go's {new,put}StackAllocState.
+	stackAllocState *stackAllocState
+
+	domblockstore []ID         // scratch space for computing dominators
+	scrSparseSet  []*sparseSet // scratch sparse sets to be re-used.
+	scrSparseMap  []*sparseMap // scratch sparse maps to be re-used.
+	scrPoset      []*poset     // scratch poset to be reused
+	// deadcode contains reusable slices specifically for the deadcode pass.
+	// It gets special treatment because of the frequency with which it is run.
+	deadcode struct {
+		liveOrderStmts []*Value
+		live           []bool
+		q              []*Value
+	}
+	// Reusable regalloc state.
+	regallocValues []valState
+
+	ValueToProgAfter []*obj.Prog
+	debugState       debugState
+
+	Liveness interface{} // *gc.livenessFuncCache
+}
+
+func (c *Cache) Reset() {
+	nv := sort.Search(len(c.values), func(i int) bool { return c.values[i].ID == 0 })
+	xv := c.values[:nv]
+	for i := range xv {
+		xv[i] = Value{}
+	}
+	nb := sort.Search(len(c.blocks), func(i int) bool { return c.blocks[i].ID == 0 })
+	xb := c.blocks[:nb]
+	for i := range xb {
+		xb[i] = Block{}
+	}
+	nl := sort.Search(len(c.locs), func(i int) bool { return c.locs[i] == nil })
+	xl := c.locs[:nl]
+	for i := range xl {
+		xl[i] = nil
+	}
+
+	// regalloc sets the length of c.regallocValues to whatever it may use,
+	// so clear according to length.
+	for i := range c.regallocValues {
+		c.regallocValues[i] = valState{}
+	}
+
+	// liveOrderStmts gets used multiple times during compilation of a function.
+	// We don't know where the high water mark was, so reslice to cap and search.
+	c.deadcode.liveOrderStmts = c.deadcode.liveOrderStmts[:cap(c.deadcode.liveOrderStmts)]
+	no := sort.Search(len(c.deadcode.liveOrderStmts), func(i int) bool { return c.deadcode.liveOrderStmts[i] == nil })
+	xo := c.deadcode.liveOrderStmts[:no]
+	for i := range xo {
+		xo[i] = nil
+	}
+	c.deadcode.q = c.deadcode.q[:cap(c.deadcode.q)]
+	nq := sort.Search(len(c.deadcode.q), func(i int) bool { return c.deadcode.q[i] == nil })
+	xq := c.deadcode.q[:nq]
+	for i := range xq {
+		xq[i] = nil
+	}
+}