cmd/compile: remove values from const cache upon free

When calling freeValue for possible const values, remove them from the
cache as well.

Change-Id: I087ed592243e33c58e5db41700ab266fc70196d9
Reviewed-on: https://go-review.googlesource.com/20481
Run-TryBot: Todd Neal <tolchz@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

1 files changed, 22 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/ssa/func_test.go b/src/cmd/compile/internal/ssa/func_test.go
index fa6a1a8751..4fef782afc 100644
--- a/src/cmd/compile/internal/ssa/func_test.go
+++ b/src/cmd/compile/internal/ssa/func_test.go
@@ -421,6 +421,28 @@ func TestEquiv(t *testing.T) {
 	}
 }
 
+// TestConstCache ensures that the cache will not return
+// reused free'd values with a non-matching AuxInt
+func TestConstCache(t *testing.T) {
+	f := Fun(testConfig(t), "entry",
+		Bloc("entry",
+			Valu("mem", OpInitMem, TypeMem, 0, nil),
+			Exit("mem")))
+	v1 := f.f.ConstBool(0, TypeBool, false)
+	v2 := f.f.ConstBool(0, TypeBool, true)
+	f.f.freeValue(v1)
+	f.f.freeValue(v2)
+	v3 := f.f.ConstBool(0, TypeBool, false)
+	v4 := f.f.ConstBool(0, TypeBool, true)
+	if v3.AuxInt != 0 {
+		t.Errorf("expected %s to have auxint of 0\n", v3.LongString())
+	}
+	if v4.AuxInt != 1 {
+		t.Errorf("expected %s to have auxint of 1\n", v4.LongString())
+	}
+
+}
+
 // opcodeMap returns a map from opcode to the number of times that opcode
 // appears in the function.
 func opcodeMap(f *Func) map[Op]int {