cmd/compile: add 2 phiopt cases

Add 2 more cases:

if a { x = value } else { x = a } => x = a && value
if a { x = a } else { x = value } => x = a || value

AND case goes from:

00006 (8)	TESTB	AX, AX
00007 (8)	JNE	9
00008 (13)	MOVL	AX, BX
00009 (13)	MOVL	BX, AX
00010 (13)	RET

to:

00006 (13)	ANDL	BX, AX
00007 (13)	RET

OR goes from:

00006 (19)	TESTB	AX, AX
00007 (19)	JNE	9
00008 (24)	MOVL	BX, AX
00009 (24)	RET

to:

00006 (24)	ORL	BX, AX
00007 (24)	RET

compilecmp linux/amd64:

runtime
runtime.lock2 847 -> 869  (+2.60%)
runtime.addspecial 542 -> 517  (-4.61%)
runtime.tracebackPCs changed
runtime.scanstack changed
runtime.mallocinit changed
runtime.traceback2 2238 -> 2206  (-1.43%)

runtime [cmd/compile]
runtime.lock2 860 -> 882  (+2.56%)
runtime.scanstack changed
runtime.addspecial 542 -> 517  (-4.61%)
runtime.traceback2 2238 -> 2206  (-1.43%)
runtime.lockWithRank 870 -> 890  (+2.30%)
runtime.tracebackPCs changed
runtime.mallocinit changed

strconv
strconv.ryuFtoaFixed32 changed
strconv.ryuFtoaFixed64 639 -> 638  (-0.16%)
strconv.readFloat changed
strconv.ryuFtoaShortest changed

strings
strings.(*Replacer).build changed

strconv [cmd/compile]
strconv.readFloat changed
strconv.ryuFtoaFixed64 639 -> 638  (-0.16%)
strconv.ryuFtoaFixed32 changed
strconv.ryuFtoaShortest changed

strings [cmd/compile]
strings.(*Replacer).build changed

regexp
regexp.makeOnePass.func1 changed

regexp [cmd/compile]
regexp.makeOnePass.func1 changed

encoding/json
encoding/json.indirect changed

database/sql
database/sql.driverArgsConnLocked changed

vendor/golang.org/x/text/unicode/norm
vendor/golang.org/x/text/unicode/norm.Form.transform changed

go/doc/comment
go/doc/comment.parseSpans changed

internal/diff
internal/diff.tgs changed

log/slog
log/slog.(*handleState).appendNonBuiltIns 1898 -> 1877  (-1.11%)

testing/fstest
testing/fstest.(*fsTester).checkGlob changed

runtime/pprof
runtime/pprof.(*profileBuilder).build changed

cmd/internal/dwarf
cmd/internal/dwarf.isEmptyInlinedCall 254 -> 244  (-3.94%)

go/printer
go/printer.keepTypeColumn 302 -> 270  (-10.60%)
go/printer.(*printer).binaryExpr changed

cmd/compile/internal/syntax
cmd/compile/internal/syntax.(*scanner).rune changed
cmd/compile/internal/syntax.(*scanner).number 2137 -> 2153  (+0.75%)

Change-Id: I7f95f54b03a35d0b616c40f38b415a7feb71be73
Reviewed-on: https://go-review.googlesource.com/c/go/+/666835
Reviewed-by: Keith Randall <khr@golang.org>
Auto-Submit: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Run-TryBot: Jakub Ciolek <jakub@ciolek.dev>
TryBot-Bypass: Keith Randall <khr@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

src/cmd/compile/internal/ssa/phiopt.go

@@ -119,6 +119,33 @@ func phiopt(f *Func) {
 					continue
 				}
 			}
+			// Replaces
+			//   if a { x = value } else { x = a } with x = a && value.
+			// Requires that value dominates x.
+			if v.Args[1-reverse] == b0.Controls[0] {
+				if tmp := v.Args[reverse]; sdom.IsAncestorEq(tmp.Block, b) {
+					v.reset(OpAndB)
+					v.SetArgs2(b0.Controls[0], tmp)
+					if f.pass.debug > 0 {
+						f.Warnl(b.Pos, "converted OpPhi to %v", v.Op)
+					}
+					continue
+				}
+			}
+
+			// Replaces
+			//   if a { x = a } else { x = value } with x = a || value.
+			// Requires that value dominates x.
+			if v.Args[reverse] == b0.Controls[0] {
+				if tmp := v.Args[1-reverse]; sdom.IsAncestorEq(tmp.Block, b) {
+					v.reset(OpOrB)
+					v.SetArgs2(b0.Controls[0], tmp)
+					if f.pass.debug > 0 {
+						f.Warnl(b.Pos, "converted OpPhi to %v", v.Op)
+					}
+					continue
+				}
+			}
 		}
 	}
 	// strengthen phi optimization.

test/codegen/bool.go

@@ -62,6 +62,30 @@ func convertEqBool64(x uint64) bool {
 	return x&1 == 0
 }
 
+func phiAnd(a, b bool) bool {
+	var x bool
+	// amd64:-"TESTB"
+	if a {
+		x = b
+	} else {
+		x = a
+	}
+	// amd64:"ANDL"
+	return x
+}
+
+func phiOr(a, b bool) bool {
+	var x bool
+	// amd64:-"TESTB"
+	if a {
+		x = a
+	} else {
+		x = b
+	}
+	// amd64:"ORL"
+	return x
+}
+
 func TestSetEq64(x uint64, y uint64) bool {
 	// ppc64x/power10:"SETBC\tCR0EQ",-"ISEL"
 	// ppc64x/power9:"CMP","ISEL",-"SETBC\tCR0EQ"

test/phiopt.go

@@ -129,5 +129,27 @@ func f9(a, b int) bool {
 	return c
 }
 
+//go:noinline
+func f10and(a bool, b bool) bool {
+	var x bool
+	if a {
+		x = b
+	} else {
+		x = a
+	}
+	return x // ERROR "converted OpPhi to AndB$"
+}
+
+//go:noinline
+func f11or(a bool, b bool) bool {
+	var x bool
+	if a {
+		x = a
+	} else {
+		x = b
+	}
+	return x // ERROR "converted OpPhi to OrB$"
+}
+
 func main() {
 }