diff --git a/src/cmd/compile/internal/ssa/gen/generic.rules b/src/cmd/compile/internal/ssa/gen/generic.rules index 99f8d0a984e02..7891d42d8ad14 100644 --- a/src/cmd/compile/internal/ssa/gen/generic.rules +++ b/src/cmd/compile/internal/ssa/gen/generic.rules @@ -650,6 +650,7 @@ (NeqPtr (ConstNil) p) -> (IsNonNil p) (EqPtr p (ConstNil)) -> (Not (IsNonNil p)) (EqPtr (ConstNil) p) -> (Not (IsNonNil p)) +(IsNonNil (ConstNil)) -> (ConstBool [0]) // slice and interface comparisons // The frontend ensures that we can only compare against nil, diff --git a/src/cmd/compile/internal/ssa/rewritegeneric.go b/src/cmd/compile/internal/ssa/rewritegeneric.go index 0fde363b3eefe..9fcffce0c71cd 100644 --- a/src/cmd/compile/internal/ssa/rewritegeneric.go +++ b/src/cmd/compile/internal/ssa/rewritegeneric.go @@ -114,6 +114,8 @@ func rewriteValuegeneric(v *Value, config *Config) bool { return rewriteValuegeneric_OpIMake(v, config) case OpIsInBounds: return rewriteValuegeneric_OpIsInBounds(v, config) + case OpIsNonNil: + return rewriteValuegeneric_OpIsNonNil(v, config) case OpIsSliceInBounds: return rewriteValuegeneric_OpIsSliceInBounds(v, config) case OpLeq16: @@ -3407,6 +3409,23 @@ func rewriteValuegeneric_OpIsInBounds(v *Value, config *Config) bool { } return false } +func rewriteValuegeneric_OpIsNonNil(v *Value, config *Config) bool { + b := v.Block + _ = b + // match: (IsNonNil (ConstNil)) + // cond: + // result: (ConstBool [0]) + for { + v_0 := v.Args[0] + if v_0.Op != OpConstNil { + break + } + v.reset(OpConstBool) + v.AuxInt = 0 + return true + } + return false +} func rewriteValuegeneric_OpIsSliceInBounds(v *Value, config *Config) bool { b := v.Block _ = b