sample: make mutations in transforms explicit (#9743)

* updated minP to use early exit making use of sorted tokens

sample/transforms.go

@@ -26,17 +26,16 @@ func (h *tokenHeap) Pop() any {
 }
 
 // temperature applies scaling to the logits
-func temperature(ts []token, temp float32) []token {
+func temperature(ts []token, temp float32) {
 	// Ensure temperature clipping near 0 to avoid numerical instability
 	temp = max(temp, 1e-7)
 	for i := range ts {
 		ts[i].value = ts[i].value / temp
 	}
-	return ts
 }
 
 // softmax applies normalization to the logits
-func softmax(ts []token) []token {
+func softmax(ts []token) {
 	// Find max logit for numerical stability
 	maxLogit := float32(math.Inf(-1))
 	for _, t := range ts {
@@ -56,8 +55,6 @@ func softmax(ts []token) []token {
 	for i := range ts {
 		ts[i].value /= sum
 	}
-
-	return ts
 }
 
 // topK limits the number of tokens considered to the k highest logits
@@ -99,6 +96,7 @@ func topK(ts []token, k int) []token {
 }
 
 // topP limits tokens to those with cumulative probability p
+// requires ts to be sorted in descending order of probabilities
 func topP(ts []token, p float32) []token {
 	if p == 1.0 {
 		return ts
@@ -109,37 +107,24 @@ func topP(ts []token, p float32) []token {
 	for i, t := range ts {
 		sum += t.value
 		if sum > float32(p) {
-			ts = ts[:i+1]
-			return ts
+			return ts[:i+1]
 		}
 	}
 
 	return ts
 }
 
-// minP limits tokens to those with cumulative probability p
+// minP filters tokens with probabilities >= p * max_prob
+// requires ts to be sorted in descending order of probabilities
 func minP(ts []token, p float32) []token {
-	if p == 1.0 {
-		return ts
-	}
+	maxProb := ts[0].value
 
-	maxProb := float32(math.Inf(-1))
-	for _, token := range ts {
-		if token.value > maxProb {
-			maxProb = token.value
+	threshold := maxProb * p
+
+	for i, t := range ts {
+		if t.value < threshold {
+			return ts[:i]
 		}
 	}
-
-	threshold := maxProb * float32(p)
-
-	// Filter tokens in-place
-	validTokens := ts[:0]
-	for i, token := range ts {
-		if token.value >= threshold {
-			validTokens = append(validTokens, ts[i])
-		}
-	}
-
-	ts = validTokens
 	return ts
 }