PR #19913: [ROCm] Do not use fast approximation for exp and log

[copybara-service]

PR #19913: [ROCm] Do not use fast approximation for exp and log

Imported from GitHub PR #19913

Error started occurring from this commit for exp 6e9eefe (originally introduced here 9b19353#diff-61ab646c9c3b8b0fc5ed1e9a62f535e9df5843adddd071250343f3bec48eacb6) and from this one 53d5338 for log.

Trying to compile following MLIR code:

HloModule module

ENTRY main {
      p0 = bf16[4] parameter(0)
      ROOT exp = bf16[4] exp(p0)
}

would result in:

UNKNOWN: <unknown>:0: error: loc(callsite("wrapped_exponential" at "wrapped_exponential")): failed to legalize operation 'math.exp'
<unknown>:0: note: loc("wrapped_exponential"): called from
<unknown>:0: note: loc(callsite("wrapped_exponential" at "wrapped_exponential")): see current operation: %7 = "math.exp"(%6) <{fastmath = #arith.fastmath<afn>}> : (bf16) -> bf16

Copybara import of the project:

--
616c10b by Milica Makevic [email protected]:

Do not use fast approximation for exp and log for ROCm

--
3fa4914 by Milica Makevic [email protected]:

Add unit test for log and exp lowering on ROCm

Merging this change closes #19913

FUTURE_COPYBARA_INTEGRATE_REVIEW=#19913 from ROCm:fix_exp_log_lowering 3fa4914