diff options
| -rw-r--r-- | src/cmd/compile/internal/ssa/prove.go | 32 |
1 files changed, 17 insertions, 15 deletions
diff --git a/src/cmd/compile/internal/ssa/prove.go b/src/cmd/compile/internal/ssa/prove.go index 3de964f061..c9f75daa67 100644 --- a/src/cmd/compile/internal/ssa/prove.go +++ b/src/cmd/compile/internal/ssa/prove.go @@ -250,6 +250,10 @@ func fitsInBitsU(x uint64, b uint) bool { return x>>b == 0 } +func noLimit() limit { + return noLimitForBitsize(64) +} + func noLimitForBitsize(bitsize uint) limit { return limit{min: -(1 << (bitsize - 1)), max: 1<<(bitsize-1) - 1, umin: 0, umax: 1<<bitsize - 1} } @@ -302,7 +306,7 @@ func (l limit) add(l2 limit, b uint) limit { return limit{min: int64r, max: int64r, umin: r, umax: r} } - r := noLimit + r := noLimit() min, minOk := safeAdd(l.min, l2.min, b) max, maxOk := safeAdd(l.max, l2.max, b) if minOk && maxOk { @@ -320,7 +324,7 @@ func (l limit) add(l2 limit, b uint) limit { // same as add but for subtraction. func (l limit) sub(l2 limit, b uint) limit { - r := noLimit + r := noLimit() min, minOk := safeSub(l.min, l2.max, b) max, maxOk := safeSub(l.max, l2.min, b) if minOk && maxOk { @@ -338,7 +342,7 @@ func (l limit) sub(l2 limit, b uint) limit { // same as add but for multiplication. func (l limit) mul(l2 limit, b uint) limit { - r := noLimit + r := noLimit() umaxhi, umaxlo := bits.Mul64(l.umax, l2.umax) if umaxhi == 0 && fitsInBitsU(umaxlo, b) { r.umax = umaxlo @@ -360,7 +364,7 @@ func (l limit) mul(l2 limit, b uint) limit { // Similar to add, but compute 1 << l if it fits without overflow in b bits. func (l limit) exp2(b uint) limit { - r := noLimit + r := noLimit() if l.umax < uint64(b) { r.umin = 1 << l.umin r.umax = 1 << l.umax @@ -423,14 +427,14 @@ func (l limit) ctz(b uint) limit { if l.umin&((1<<varying)-1) != 0 { // there will always be at least one non-zero bit in the varying part varying-- - return noLimit.unsignedMax(uint64(varying)) + return noLimit().unsignedMax(uint64(varying)) } - return noLimit.unsignedMax(uint64(min(uint(bits.TrailingZeros64(fixed)), b))) + return noLimit().unsignedMax(uint64(min(uint(bits.TrailingZeros64(fixed)), b))) } // Similar to add, but computes the Len of the limit for bitsize b. func (l limit) bitlen(b uint) limit { - return noLimit.unsignedMinMax( + return noLimit().unsignedMinMax( uint64(bits.Len64(l.umin)), uint64(bits.Len64(l.umax)), ) @@ -456,11 +460,9 @@ func (l limit) popcount(b uint) limit { min++ } - return noLimit.unsignedMinMax(min, max) + return noLimit().unsignedMinMax(min, max) } -var noLimit = limit{math.MinInt64, math.MaxInt64, 0, math.MaxUint64} - // a limitFact is a limit known for a particular value. type limitFact struct { vid ID @@ -611,7 +613,7 @@ func (ft *factsTable) pointerNil(v *Value) { ft.newLimit(v, limit{min: 0, max: 0, umin: 0, umax: 0}) } func (ft *factsTable) pointerNonNil(v *Value) { - l := noLimit + l := noLimit() l.umin = 1 ft.newLimit(v, l) } @@ -1843,15 +1845,15 @@ func initLimit(v *Value) limit { case OpConstNil: return limit{min: 0, max: 0, umin: 0, umax: 0} case OpAddr, OpLocalAddr: // TODO: others? - l := noLimit + l := noLimit() l.umin = 1 return l default: - return noLimit + return noLimit() } } if !v.Type.IsInteger() { - return noLimit + return noLimit() } // Default limits based on type. @@ -2063,7 +2065,7 @@ func (ft *factsTable) flowLimit(v *Value) { case OpDiv64u, OpDiv32u, OpDiv16u, OpDiv8u: a := ft.limits[v.Args[0].ID] b := ft.limits[v.Args[1].ID] - lim := noLimit + lim := noLimit() if b.umax > 0 { lim = lim.unsignedMin(a.umin / b.umax) } |