[clang] [flang] Add IR Profile-Guided Optimization (IR PGO) support to the Flang compiler (PR #136098)

[via cfe-commits]

fanju110 wrote:



The following is the Fortran benchmark test data from speccpu2006

|              | Runtime without PGO (Sec) | Runtime with PGO (Sec) | Speedup |
| ------------ | ------------------------- | ---------------------- | ------- |
| 410.bwaves   | 101                       | 97.6                   | 1.03    |
| 416.gamess   | 259                       | 244                    | 1.06    |
| 434.zeusmp   | 88.8                      | 91                     | 0.98    |
| 437.leslie3d | 94.7                      | 94.1                   | 1.01    |
| 454.calculix | 182                       | 180                    | 1.01    |
| 459.GemsFDTD | 176                       | 187                    | 0.94    |
| 465.tonto    | 118                       | 124                    | 0.95    |
| 481.wrf      | 93.4                      | 91.4                   | 1.02    |

* Complier: LLVM 20.1.0
* Options: 
  * without PGO: 
    * -O3 -flto -ffast-math 
  * with PGO:     
    * -O3 -flto -ffast-math -fprofile-generate
    * -O3 -flto -ffast-math -fprofile-use=<dir>/file

* Hardware: 11th Gen Intel(R) Core(TM) i9-11900K @ 3.50GHz
* OS: Ubuntu20.04.6 LTS (Focal Fossa)



https://github.com/llvm/llvm-project/pull/136098