[llvm] [ConstantFolding] Consider `tanh*` to always be a noop (PR #70794)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `ml-opt-rel-x86-64` running on `ml-opt-rel-x86-64-b2` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/185/builds/35002

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM :: Transforms/EarlyCSE/math-1.ll' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 2
/b/ml-opt-rel-x86-64-b1/build/bin/opt -passes=early-cse -earlycse-debug-hash -S -o - /b/ml-opt-rel-x86-64-b1/llvm-project/llvm/test/Transforms/EarlyCSE/math-1.ll | /b/ml-opt-rel-x86-64-b1/build/bin/FileCheck /b/ml-opt-rel-x86-64-b1/llvm-project/llvm/test/Transforms/EarlyCSE/math-1.ll
# executed command: /b/ml-opt-rel-x86-64-b1/build/bin/opt -passes=early-cse -earlycse-debug-hash -S -o - /b/ml-opt-rel-x86-64-b1/llvm-project/llvm/test/Transforms/EarlyCSE/math-1.ll
# executed command: /b/ml-opt-rel-x86-64-b1/build/bin/FileCheck /b/ml-opt-rel-x86-64-b1/llvm-project/llvm/test/Transforms/EarlyCSE/math-1.ll
# .---command stderr------------
# | /b/ml-opt-rel-x86-64-b1/llvm-project/llvm/test/Transforms/EarlyCSE/math-1.ll:189:15: error: CHECK-NEXT: expected string not found in input
# | ; CHECK-NEXT: [[RES:%.*]] = tail call fast float @tanhf(float 1.000000e+00)
# |               ^
# | <stdin>:148:23: note: scanning from here
# | define float @f_tanhf() {
# |                       ^
# | <stdin>:149:2: note: possible intended match here
# |  ret float 0x3FE85EFAC0000000
# |  ^
# | 
# | Input file: <stdin>
# | Check file: /b/ml-opt-rel-x86-64-b1/llvm-project/llvm/test/Transforms/EarlyCSE/math-1.ll
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |             .
# |             .
# |             .
# |           143: } 
# |           144:  
# |           145: ; Function Attrs: nofree nounwind willreturn 
# |           146: declare float @tanhf(float) #0 
# |           147:  
# |           148: define float @f_tanhf() { 
# | next:189'0                           X~~~ error: no match found
# |           149:  ret float 0x3FE85EFAC0000000 
# | next:189'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# | next:189'1      ?                             possible intended match
# |           150: } 
# | next:189'0     ~~
# |           151:  
# | next:189'0     ~
# |           152: attributes #0 = { nofree nounwind willreturn } 
# | next:189'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |           153: attributes #1 = { nocallback nocreateundeforpoison nofree nosync nounwind speculatable willreturn memory(none) } 
# | next:189'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# | >>>>>>
# `-----------------------------
...

```

</details>

https://github.com/llvm/llvm-project/pull/70794