types: make chopPrecisionAndTruncate always non-mutative (#9250)

Currently, chopPrecisionAndTruncate/chopPrecisionAndTruncateNonMutative
are doing the same thing, except that the former do it mutatively.

Looking at the usages of chopPrecisionAndTruncate, the callers must
alloc a new big.Int before calling it anyway, so any mutation will be
done with this new allocated big.Int, instead of input argument.

So, by making chopPrecisionAndTruncate always non-mutative, we simplify
the code, and make the code faster, less allocation in some benchmarks.

Benchmark for github.com/cosmos/cosmos-sdk/types:

name                                           old time/op    new time/op    delta
CoinsAdditionIntersect/sizes:_A_1,_B_1-8         35.4ns ± 0%    35.1ns ± 0%  -0.92%  (p=0.008 n=5+5)
CoinsAdditionIntersect/sizes:_A_5,_B_5-8          366ns ± 1%     363ns ± 1%    ~     (p=0.056 n=5+5)
CoinsAdditionIntersect/sizes:_A_5,_B_20-8         557ns ± 0%     553ns ± 0%  -0.64%  (p=0.008 n=5+5)
CoinsAdditionIntersect/sizes:_A_1,_B_1000-8      6.17µs ± 0%    6.18µs ± 0%    ~     (p=0.151 n=5+5)
CoinsAdditionIntersect/sizes:_A_2,_B_1000-8      6.30µs ± 0%    6.32µs ± 0%  +0.23%  (p=0.008 n=5+5)
CoinsAdditionNoIntersect/sizes:_A_1,_B_1-8       30.2ns ± 0%    29.9ns ± 1%  -0.98%  (p=0.008 n=5+5)
CoinsAdditionNoIntersect/sizes:_A_5,_B_5-8        226ns ± 0%     224ns ± 0%  -0.54%  (p=0.008 n=5+5)
CoinsAdditionNoIntersect/sizes:_A_5,_B_20-8       373ns ± 0%     372ns ± 0%  -0.26%  (p=0.040 n=5+5)
CoinsAdditionNoIntersect/sizes:_A_1,_B_1000-8    6.21µs ± 0%    6.22µs ± 0%    ~     (p=0.421 n=5+5)
CoinsAdditionNoIntersect/sizes:_A_2,_B_1000-8    6.22µs ± 0%    6.23µs ± 0%    ~     (p=0.286 n=5+5)
CoinsAdditionNoIntersect/sizes:_A_1000,_B_2-8    6.22µs ± 0%    6.23µs ± 0%    ~     (p=0.143 n=5+5)
ParseCoin-8                                      5.46µs ± 0%    5.39µs ± 0%  -1.26%  (p=0.008 n=5+5)
UintMarshal-8                                    1.01µs ± 0%    1.00µs ± 0%  -1.10%  (p=0.008 n=5+5)
IntMarshal-8                                      764ns ± 0%     758ns ± 1%  -0.79%  (p=0.024 n=5+5)
MarshalTo-8                                       192ns ± 0%     190ns ± 0%  -1.03%  (p=0.008 n=5+5)

name                                           old alloc/op   new alloc/op   delta
CoinsAdditionIntersect/sizes:_A_1,_B_1-8          32.0B ± 0%     32.0B ± 0%    ~     (all equal)
CoinsAdditionIntersect/sizes:_A_5,_B_5-8           520B ± 0%      520B ± 0%    ~     (all equal)
CoinsAdditionIntersect/sizes:_A_5,_B_20-8        1.38kB ± 0%    1.38kB ± 0%    ~     (all equal)
CoinsAdditionIntersect/sizes:_A_1,_B_1000-8      49.2kB ± 0%    49.2kB ± 0%    ~     (all equal)
CoinsAdditionIntersect/sizes:_A_2,_B_1000-8      49.3kB ± 0%    49.3kB ± 0%    ~     (all equal)
CoinsAdditionNoIntersect/sizes:_A_1,_B_1-8        24.0B ± 0%     24.0B ± 0%    ~     (all equal)
CoinsAdditionNoIntersect/sizes:_A_5,_B_5-8         488B ± 0%      488B ± 0%    ~     (all equal)
CoinsAdditionNoIntersect/sizes:_A_5,_B_20-8      1.35kB ± 0%    1.35kB ± 0%    ~     (all equal)
CoinsAdditionNoIntersect/sizes:_A_1,_B_1000-8    49.2kB ± 0%    49.2kB ± 0%    ~     (all equal)
CoinsAdditionNoIntersect/sizes:_A_2,_B_1000-8    49.2kB ± 0%    49.2kB ± 0%    ~     (all equal)
CoinsAdditionNoIntersect/sizes:_A_1000,_B_2-8    49.2kB ± 0%    49.2kB ± 0%    ~     (all equal)
ParseCoin-8                                      2.21kB ± 0%    2.21kB ± 0%    ~     (all equal)
UintMarshal-8                                      392B ± 0%      392B ± 0%    ~     (all equal)
IntMarshal-8                                       168B ± 0%      168B ± 0%    ~     (all equal)
MarshalTo-8                                       80.0B ± 0%     80.0B ± 0%    ~     (all equal)

name                                           old allocs/op  new allocs/op  delta
CoinsAdditionIntersect/sizes:_A_1,_B_1-8           1.00 ± 0%      1.00 ± 0%    ~     (all equal)
CoinsAdditionIntersect/sizes:_A_5,_B_5-8           12.0 ± 0%      12.0 ± 0%    ~     (all equal)
CoinsAdditionIntersect/sizes:_A_5,_B_20-8          14.0 ± 0%      14.0 ± 0%    ~     (all equal)
CoinsAdditionIntersect/sizes:_A_1,_B_1000-8        3.00 ± 0%      3.00 ± 0%    ~     (all equal)
CoinsAdditionIntersect/sizes:_A_2,_B_1000-8        6.00 ± 0%      6.00 ± 0%    ~     (all equal)
CoinsAdditionNoIntersect/sizes:_A_1,_B_1-8         1.00 ± 0%      1.00 ± 0%    ~     (all equal)
CoinsAdditionNoIntersect/sizes:_A_5,_B_5-8         5.00 ± 0%      5.00 ± 0%    ~     (all equal)
CoinsAdditionNoIntersect/sizes:_A_5,_B_20-8        6.00 ± 0%      6.00 ± 0%    ~     (all equal)
CoinsAdditionNoIntersect/sizes:_A_1,_B_1000-8      3.00 ± 0%      3.00 ± 0%    ~     (all equal)
CoinsAdditionNoIntersect/sizes:_A_2,_B_1000-8      4.00 ± 0%      4.00 ± 0%    ~     (all equal)
CoinsAdditionNoIntersect/sizes:_A_1000,_B_2-8      3.00 ± 0%      3.00 ± 0%    ~     (all equal)
ParseCoin-8                                        71.0 ± 0%      71.0 ± 0%    ~     (all equal)
UintMarshal-8                                      25.0 ± 0%      25.0 ± 0%    ~     (all equal)
IntMarshal-8                                       18.0 ± 0%      18.0 ± 0%    ~     (all equal)
MarshalTo-8                                        2.00 ± 0%      2.00 ± 0%    ~     (all equal)

name                                           old speed      new speed      delta
UintMarshal-8                                  6.91MB/s ± 0%  6.99MB/s ± 0%  +1.04%  (p=0.008 n=5+5)
IntMarshal-8                                   9.16MB/s ± 0%  9.23MB/s ± 1%  +0.83%  (p=0.032 n=5+5)

Benchmark for github.com/cosmos/cosmos-sdk/x/mint/types:

name              old time/op    new time/op    delta
BlockProvision-8     263ns ± 0%     257ns ± 0%   -2.23%  (p=0.008 n=5+5)

name              old alloc/op   new alloc/op   delta
BlockProvision-8      112B ± 0%      104B ± 0%   -7.14%  (p=0.008 n=5+5)

name              old allocs/op  new allocs/op  delta
BlockProvision-8      6.00 ± 0%      5.00 ± 0%  -16.67%  (p=0.008 n=5+5)

Fixes #9249

Co-authored-by: Emmanuel T Odeke <[email protected]>

types/decimal.go

@@ -301,7 +301,7 @@ func (d Dec) QuoTruncate(d2 Dec) Dec {
 	mul := new(big.Int).Mul(d.i, precisionReuse)
 	mul.Mul(mul, precisionReuse)
 
-	quo := new(big.Int).Quo(mul, d2.i)
+	quo := mul.Quo(mul, d2.i)
 	chopped := chopPrecisionAndTruncate(quo)
 
 	if chopped.BitLen() > 255+DecimalPrecisionBits {
@@ -560,19 +560,15 @@ func (d Dec) RoundInt() Int {
 	return NewIntFromBigInt(chopPrecisionAndRoundNonMutative(d.i))
 }
 
-// similar to chopPrecisionAndRound, but always rounds down
+// chopPrecisionAndTruncate is similar to chopPrecisionAndRound,
+// but always rounds down. It does not mutate the input.
 func chopPrecisionAndTruncate(d *big.Int) *big.Int {
-	return d.Quo(d, precisionReuse)
-}
-
-func chopPrecisionAndTruncateNonMutative(d *big.Int) *big.Int {
-	tmp := new(big.Int).Set(d)
-	return chopPrecisionAndTruncate(tmp)
+	return new(big.Int).Quo(d, precisionReuse)
 }
 
 // TruncateInt64 truncates the decimals from the number and returns an int64
 func (d Dec) TruncateInt64() int64 {
-	chopped := chopPrecisionAndTruncateNonMutative(d.i)
+	chopped := chopPrecisionAndTruncate(d.i)
 	if !chopped.IsInt64() {
 		panic("Int64() out of bound")
 	}
@@ -581,12 +577,12 @@ func (d Dec) TruncateInt64() int64 {
 
 // TruncateInt truncates the decimals from the number and returns an Int
 func (d Dec) TruncateInt() Int {
-	return NewIntFromBigInt(chopPrecisionAndTruncateNonMutative(d.i))
+	return NewIntFromBigInt(chopPrecisionAndTruncate(d.i))
 }
 
 // TruncateDec truncates the decimals from the number and returns a Dec
 func (d Dec) TruncateDec() Dec {
-	return NewDecFromBigInt(chopPrecisionAndTruncateNonMutative(d.i))
+	return NewDecFromBigInt(chopPrecisionAndTruncate(d.i))
 }
 
 // Ceil returns the smallest interger value (as a decimal) that is greater than