separate paddle.logsumexp (#3897)

paddlespeech/s2t/models/whisper/whisper.py

@@ -971,8 +971,14 @@ class ApplyTimestampRules(LogitFilter):
         # if sum of probability over timestamps is above any other token, sample timestamp
         logprobs = F.log_softmax(logits, axis=-1, dtype=paddle.float32)
         for k in range(tokens.shape[0]):
-            timestamp_logprob = paddle.logsumexp(
-                logprobs[k, self.tokenizer.timestamp_begin:], axis=-1)
+            # When using paddle.logsumexp on a 32GB Tesla-V100 GPU, we encountered CUDA error 700. 
+            # To bypass this issue in CI, we have decomposed the operation into separate steps. 
+            # It will raise 2e-6 difference in precision.
+            # TODO: revert this after logsumexp been fixed.
+            timestamp_logprob = paddle.exp(
+                logprobs[k, self.tokenizer.timestamp_begin:])
+            timestamp_logprob = paddle.sum(timestamp_logprob, axis=-1)
+            timestamp_logprob = paddle.log(timestamp_logprob)
             max_text_token_logprob = paddle.max(
                 logprobs[k, :self.tokenizer.timestamp_begin])
             if timestamp_logprob > max_text_token_logprob: