cmd/compile: redo flag constant ops for arm

Encode the flag results in an auxint field instead of having
one opcode per flag state. This helps us handle the new *noov
branches in a unified manner.

This is only for arm, arm64 is in a subsequent CL.

We could extend to other architectures as well, athough it would
only be cleanup, no behavioral change.

Update #39505

Change-Id: Ia46cea596faad540d1496c5915ab1274571543f0
Reviewed-on: https://go-review.googlesource.com/c/go/+/238077
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/ssa/rewrite_test.go b/src/cmd/compile/internal/ssa/rewrite_test.go
index 4321c307dc..1a15d8c940 100644
--- a/src/cmd/compile/internal/ssa/rewrite_test.go
+++ b/src/cmd/compile/internal/ssa/rewrite_test.go
@@ -27,3 +27,12 @@ func TestMoveSmall(t *testing.T) {
 		}
 	}
 }
+
+func TestSubFlags(t *testing.T) {
+	if !subFlags32(0, 1).lt() {
+		t.Errorf("subFlags32(0,1).lt() returned false")
+	}
+	if !subFlags32(0, 1).ult() {
+		t.Errorf("subFlags32(0,1).ult() returned false")
+	}
+}