<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/208344>208344</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            `#pragma float_control(precise, on)`  behavior doesn't agree with docs
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          Marc-B-Reynolds
      </td>
    </tr>
</table>

<pre>
    Given `-ffast-math` on command line:  doesn't honor infinites, NaNs, setting errno and only respects any following `#pragma clang fp contract` in limited cases (see below)

https://godbolt.org/z/4z3PMEePc

local copy:

```c
#include <math.h>

// docs claim: -ffast-math turned off, -ffp-contract=on & -fmath-errno 
#pragma float_control(precise,on)


int is_ordered(float x) { return x == x; }        // not respecting NaNs
int is_inf(float x)     { return isinf(x); }      // not respecting inf
float my_sqrt(float x)  { return sqrtf(x); }      // good answer IMHO but not what doc's say

// correct to documentation: fusing on
float madd0(float a, float b, float c) { return a*b+c; }

// strange case: the pragma is respect if -ffp-contract={on, off, fast-honor-pragmas}
// is on the command line. But anyway: again not agreeing with documentation.
// we should be equivalent to -ffp-contract=on at this point..so this should be respected
// by my reading.
#pragma clang fp contract(off)
float madd1(float a, float b, float c) { return a*b+c; }
```

</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJysVE2T4jYQ_TXNpcuUkAcMBx9gZklymM1W_sCUPtq2UrLESvIw7K9PyfbAMLvJKRRVNqj7dfd7rSdiNK0jqmF9gPXTQgyp86F-FkEVh-IvujhvdVxIry_1b-aVHMKGFU0jYip6kTrYMPQOle974TRa4wjKPaL2FB3wKmHnnQ9oXGOcSRSBP-JX8XV8RkrJuBYpBOcx53tnLxgonkiliMJdsPHW-nOOgg0DXp6CaHuBygrXYnNC5V0KQqXciHFoTW8SaVQiUkTg20iEkqw_A98B2wPbdymdIpR74Efgx9Zr6W1a-tACP_4Afnz4UX57_kLf1BRuvRIWlT9dcs74V-5k_I4hvDRO2UETQvmYOVl2UH6ZI8caqL2KuWXTZ3I-0IdpCI40-qbJhBRNcyquE5VP3iHwDRZNji0mmqaSMw2N9SK9jBneAt-eAikTCfijd9eBge2NS2jiiw-aAmng2zER34DvEKoDBsqN4BtC-QTlE75BeUConnD-zHM4n97VyYqMOl7BjWvugcfEG7iJU0Q-u4P_NXgOZvsJrr-8xO8hfYL_gJ1P_wu79V6jcPFMAf94_v1PlEMaC547kbI8wKuIUVzuZFM-BFIJk88hQ08uiWS8yyI2Q8xdendrUmjNri2KrOf0Km-v6hPhAvheAj-ouem78jEF4VoadzmXTB3hrLuJ71ShaX5aG6gOWf7H97Ua1228h8WUH-dSUx0T8xXO6B-v8RIPQ8pX8Czy5qNohXEjZ6INRHn4s0ndPTPLG-qZMHZ-sBolIX0fzKuw5EYyf7HmImHqTMSTNy4tl9FPP28I87ikbxXkBfvsFkIb1y7v7sXP9sC3Ixm7O7lW_4Nc714AbL_Qdal35U4sqF5V23K9XjFeLbpaKhJytVsxttpVWnLN-Hq3q5SUUrBypxem5oxvWMW2nK8Zr5ZaVpXiOX21lUQreGDUC2OX1r722awWJsaBas625cPDwgpJNr6beKhzVCGHNsIDsyameMtLJlmq78z0310EJxvZMERJnXg1Pnyw9nERrlsQF0Ow9Sd3Nakb5FL5HvgxtzA_ilPwf1OW5TjOEYEf51Fea_5PAAAA___xxRRo">