go/ssa: Move BasicBlock operations into block.go

Move the BasicBlock related functions and methods into their own file. Miscellaneous cleanup. Updates golang/go#48525 Change-Id: If1c89cf53a4dba25d0c8b703e53c79eb27957f9c Reviewed-on: https://go-review.googlesource.com/c/tools/+/386316 Reviewed-by: Zvonimir Pavlinovic <zpavlinovic@google.com> Reviewed-by: Robert Findley <rfindley@google.com> Trust: Tim King <taking@google.com> Run-TryBot: Tim King <taking@google.com> gopls-CI: kokoro <noreply+kokoro@google.com> TryBot-Result: Gopher Robot <gobot@golang.org>
golang · Mar 2, 2022 · fc47946 · fc47946
1 parent 7103138
commit fc47946
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Showing 2 changed files with 119 additions and 110 deletions.
diff --git a/go/ssa/block.go b/go/ssa/block.go
@@ -0,0 +1,118 @@
+// Copyright 2022 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 "fmt"
+
+// This file implements the BasicBlock type.
+
+// addEdge adds a control-flow graph edge from from to to.
+func addEdge(from, to *BasicBlock) {
+	from.Succs = append(from.Succs, to)
+	to.Preds = append(to.Preds, from)
+}
+
+// Parent returns the function that contains block b.
+func (b *BasicBlock) Parent() *Function { return b.parent }
+
+// String returns a human-readable label of this block.
+// It is not guaranteed unique within the function.
+//
+func (b *BasicBlock) String() string {
+	return fmt.Sprintf("%d", b.Index)
+}
+
+// emit appends an instruction to the current basic block.
+// If the instruction defines a Value, it is returned.
+//
+func (b *BasicBlock) emit(i Instruction) Value {
+	i.setBlock(b)
+	b.Instrs = append(b.Instrs, i)
+	v, _ := i.(Value)
+	return v
+}
+
+// predIndex returns the i such that b.Preds[i] == c or panics if
+// there is none.
+func (b *BasicBlock) predIndex(c *BasicBlock) int {
+	for i, pred := range b.Preds {
+		if pred == c {
+			return i
+		}
+	}
+	panic(fmt.Sprintf("no edge %s -> %s", c, b))
+}
+
+// hasPhi returns true if b.Instrs contains φ-nodes.
+func (b *BasicBlock) hasPhi() bool {
+	_, ok := b.Instrs[0].(*Phi)
+	return ok
+}
+
+// phis returns the prefix of b.Instrs containing all the block's φ-nodes.
+func (b *BasicBlock) phis() []Instruction {
+	for i, instr := range b.Instrs {
+		if _, ok := instr.(*Phi); !ok {
+			return b.Instrs[:i]
+		}
+	}
+	return nil // unreachable in well-formed blocks
+}
+
+// replacePred replaces all occurrences of p in b's predecessor list with q.
+// Ordinarily there should be at most one.
+//
+func (b *BasicBlock) replacePred(p, q *BasicBlock) {
+	for i, pred := range b.Preds {
+		if pred == p {
+			b.Preds[i] = q
+		}
+	}
+}
+
+// replaceSucc replaces all occurrences of p in b's successor list with q.
+// Ordinarily there should be at most one.
+//
+func (b *BasicBlock) replaceSucc(p, q *BasicBlock) {
+	for i, succ := range b.Succs {
+		if succ == p {
+			b.Succs[i] = q
+		}
+	}
+}
+
+// removePred removes all occurrences of p in b's
+// predecessor list and φ-nodes.
+// Ordinarily there should be at most one.
+//
+func (b *BasicBlock) removePred(p *BasicBlock) {
+	phis := b.phis()
+
+	// We must preserve edge order for φ-nodes.
+	j := 0
+	for i, pred := range b.Preds {
+		if pred != p {
+			b.Preds[j] = b.Preds[i]
+			// Strike out φ-edge too.
+			for _, instr := range phis {
+				phi := instr.(*Phi)
+				phi.Edges[j] = phi.Edges[i]
+			}
+			j++
+		}
+	}
+	// Nil out b.Preds[j:] and φ-edges[j:] to aid GC.
+	for i := j; i < len(b.Preds); i++ {
+		b.Preds[i] = nil
+		for _, instr := range phis {
+			instr.(*Phi).Edges[i] = nil
+		}
+	}
+	b.Preds = b.Preds[:j]
+	for _, instr := range phis {
+		phi := instr.(*Phi)
+		phi.Edges = phi.Edges[:j]
+	}
+}
diff --git a/go/ssa/func.go b/go/ssa/func.go
@@ -4,7 +4,7 @@
 
 package ssa
 
-// This file implements the Function and BasicBlock types.
+// This file implements the Function type.
 
 import (
 	"bytes"
@@ -17,115 +17,6 @@ import (
 	"strings"
 )
 
-// addEdge adds a control-flow graph edge from from to to.
-func addEdge(from, to *BasicBlock) {
-	from.Succs = append(from.Succs, to)
-	to.Preds = append(to.Preds, from)
-}
-
-// Parent returns the function that contains block b.
-func (b *BasicBlock) Parent() *Function { return b.parent }
-
-// String returns a human-readable label of this block.
-// It is not guaranteed unique within the function.
-//
-func (b *BasicBlock) String() string {
-	return fmt.Sprintf("%d", b.Index)
-}
-
-// emit appends an instruction to the current basic block.
-// If the instruction defines a Value, it is returned.
-//
-func (b *BasicBlock) emit(i Instruction) Value {
-	i.setBlock(b)
-	b.Instrs = append(b.Instrs, i)
-	v, _ := i.(Value)
-	return v
-}
-
-// predIndex returns the i such that b.Preds[i] == c or panics if
-// there is none.
-func (b *BasicBlock) predIndex(c *BasicBlock) int {
-	for i, pred := range b.Preds {
-		if pred == c {
-			return i
-		}
-	}
-	panic(fmt.Sprintf("no edge %s -> %s", c, b))
-}
-
-// hasPhi returns true if b.Instrs contains φ-nodes.
-func (b *BasicBlock) hasPhi() bool {
-	_, ok := b.Instrs[0].(*Phi)
-	return ok
-}
-
-// phis returns the prefix of b.Instrs containing all the block's φ-nodes.
-func (b *BasicBlock) phis() []Instruction {
-	for i, instr := range b.Instrs {
-		if _, ok := instr.(*Phi); !ok {
-			return b.Instrs[:i]
-		}
-	}
-	return nil // unreachable in well-formed blocks
-}
-
-// replacePred replaces all occurrences of p in b's predecessor list with q.
-// Ordinarily there should be at most one.
-//
-func (b *BasicBlock) replacePred(p, q *BasicBlock) {
-	for i, pred := range b.Preds {
-		if pred == p {
-			b.Preds[i] = q
-		}
-	}
-}
-
-// replaceSucc replaces all occurrences of p in b's successor list with q.
-// Ordinarily there should be at most one.
-//
-func (b *BasicBlock) replaceSucc(p, q *BasicBlock) {
-	for i, succ := range b.Succs {
-		if succ == p {
-			b.Succs[i] = q
-		}
-	}
-}
-
-// removePred removes all occurrences of p in b's
-// predecessor list and φ-nodes.
-// Ordinarily there should be at most one.
-//
-func (b *BasicBlock) removePred(p *BasicBlock) {
-	phis := b.phis()
-
-	// We must preserve edge order for φ-nodes.
-	j := 0
-	for i, pred := range b.Preds {
-		if pred != p {
-			b.Preds[j] = b.Preds[i]
-			// Strike out φ-edge too.
-			for _, instr := range phis {
-				phi := instr.(*Phi)
-				phi.Edges[j] = phi.Edges[i]
-			}
-			j++
-		}
-	}
-	// Nil out b.Preds[j:] and φ-edges[j:] to aid GC.
-	for i := j; i < len(b.Preds); i++ {
-		b.Preds[i] = nil
-		for _, instr := range phis {
-			instr.(*Phi).Edges[i] = nil
-		}
-	}
-	b.Preds = b.Preds[:j]
-	for _, instr := range phis {
-		phi := instr.(*Phi)
-		phi.Edges = phi.Edges[:j]
-	}
-}
-
 // Destinations associated with unlabelled for/switch/select stmts.
 // We push/pop one of these as we enter/leave each construct and for
 // each BranchStmt we scan for the innermost target of the right type.