5 files changed, 20 insertions, 2 deletions
diff --git a/src/cmd/compile/internal/base/debug.go b/src/cmd/compile/internal/base/debug.go
index 10393e773c..85873dcc40 100644
--- a/src/cmd/compile/internal/base/debug.go
+++ b/src/cmd/compile/internal/base/debug.go
@@ -40,6 +40,7 @@ type DebugFlags struct {
 	InlFuncsWithClosures  int    `help:"allow functions with closures to be inlined" concurrent:"ok"`
 	InlStaticInit         int    `help:"allow static initialization of inlined calls" concurrent:"ok"`
 	Libfuzzer             int    `help:"enable coverage instrumentation for libfuzzer"`
+	LiteralAllocHash      string `help:"hash value for use in debugging literal allocation optimizations" concurrent:"ok"`
 	LoopVar               int    `help:"shared (0, default), 1 (private loop variables), 2, private + log"`
 	LoopVarHash           string `help:"for debugging changes in loop behavior. Overrides experiment and loopvar flag."`
 	LocationLists         int    `help:"print information about DWARF location list creation"`
diff --git a/src/cmd/compile/internal/base/flag.go b/src/cmd/compile/internal/base/flag.go
index abf85c7e78..e87f57cdaa 100644
--- a/src/cmd/compile/internal/base/flag.go
+++ b/src/cmd/compile/internal/base/flag.go
@@ -268,6 +268,10 @@ func ParseFlags() {
 	if Debug.PGOHash != "" {
 		PGOHash = NewHashDebug("pgohash", Debug.PGOHash, nil)
 	}
+	if Debug.LiteralAllocHash != "" {
+		LiteralAllocHash = NewHashDebug("literalalloc", Debug.LiteralAllocHash, nil)
+	}
+
 	if Debug.MergeLocalsHash != "" {
 		MergeLocalsHash = NewHashDebug("mergelocals", Debug.MergeLocalsHash, nil)
 	}
diff --git a/src/cmd/compile/internal/base/hashdebug.go b/src/cmd/compile/internal/base/hashdebug.go
index c54b6e17aa..fa63deb46a 100644
--- a/src/cmd/compile/internal/base/hashdebug.go
+++ b/src/cmd/compile/internal/base/hashdebug.go
@@ -56,6 +56,7 @@ var hashDebug *HashDebug
 var FmaHash *HashDebug          // for debugging fused-multiply-add floating point changes
 var LoopVarHash *HashDebug      // for debugging shared/private loop variable changes
 var PGOHash *HashDebug          // for debugging PGO optimization decisions
+var LiteralAllocHash *HashDebug // for debugging literal allocation optimizations
 var MergeLocalsHash *HashDebug  // for debugging local stack slot merging changes
 var VariableMakeHash *HashDebug // for debugging variable-sized make optimizations
 
diff --git a/src/cmd/compile/internal/escape/escape.go b/src/cmd/compile/internal/escape/escape.go
index 600b986d3f..72d40bd258 100644
--- a/src/cmd/compile/internal/escape/escape.go
+++ b/src/cmd/compile/internal/escape/escape.go
@@ -567,6 +567,10 @@ func (b *batch) rewriteWithLiterals(n ir.Node, fn *ir.Func) {
 					base.Fatalf("unexpected BasicLit Kind")
 				}
 				if constant.Compare(lit.Val(), token.GEQ, constant.MakeInt64(0)) {
+					if !base.LiteralAllocHash.MatchPos(n.Pos(), nil) {
+						// De-selected by literal alloc optimizations debug hash.
+						return
+					}
 					// Preserve any side effects of the original expression, then replace it.
 					assignTemp(*r, n.PtrInit())
 					*r = lit
@@ -580,6 +584,10 @@ func (b *batch) rewriteWithLiterals(n ir.Node, fn *ir.Func) {
 		if conv.X.Op() != ir.OLITERAL && !conv.X.Type().IsInterface() {
 			v := ro.StaticValue(conv.X)
 			if v != nil && v.Op() == ir.OLITERAL && ir.ValidTypeForConst(conv.X.Type(), v.Val()) {
+				if !base.LiteralAllocHash.MatchPos(n.Pos(), nil) {
+					// De-selected by literal alloc optimizations debug hash.
+					return
+				}
 				if base.Debug.EscapeDebug >= 3 {
 					base.WarnfAt(n.Pos(), "rewriting OCONVIFACE value from %v (%v) to %v (%v)", conv.X, conv.X.Type(), v, v.Type())
 				}
diff --git a/src/cmd/compile/internal/walk/order.go b/src/cmd/compile/internal/walk/order.go
index 8ba8dd96cc..cb022faddf 100644
--- a/src/cmd/compile/internal/walk/order.go
+++ b/src/cmd/compile/internal/walk/order.go
@@ -246,14 +246,18 @@ func (o *orderState) addrTemp(n ir.Node) ir.Node {
 	if v == nil {
 		v = n
 	}
+	optEnabled := func(n ir.Node) bool {
+		// Do this optimization only when enabled for this node.
+		return base.LiteralAllocHash.MatchPos(n.Pos(), nil)
+	}
 	if (v.Op() == ir.OSTRUCTLIT || v.Op() == ir.OARRAYLIT) && !base.Ctxt.IsFIPS() {
-		if ir.IsZero(v) && 0 < v.Type().Size() && v.Type().Size() <= abi.ZeroValSize {
+		if ir.IsZero(v) && 0 < v.Type().Size() && v.Type().Size() <= abi.ZeroValSize && optEnabled(n) {
 			// This zero value can be represented by the read-only zeroVal.
 			zeroVal := ir.NewLinksymExpr(v.Pos(), ir.Syms.ZeroVal, n.Type())
 			vstat := typecheck.Expr(zeroVal).(*ir.LinksymOffsetExpr)
 			return vstat
 		}
-		if isStaticCompositeLiteral(v) {
+		if isStaticCompositeLiteral(v) && optEnabled(n) {
 			// v can be directly represented in the read-only data section.
 			lit := v.(*ir.CompLitExpr)
 			vstat := readonlystaticname(n.Type())