Commit Graph

3 Commits

Author SHA1 Message Date
Michael Kruse 650bbc5620 [OpenMP][OpenMPIRBuilder] Implement loop unrolling.
Recommit of 707ce34b06. Don't introduce a
dependency to the LLVMPasses component, instead register the required
passes individually.

Add methods for loop unrolling to the OpenMPIRBuilder class and use them in Clang if `-fopenmp-enable-irbuilder` is enabled. The unrolling methods are:

 * `unrollLoopFull`
 * `unrollLoopPartial`
 * `unrollLoopHeuristic`

`unrollLoopPartial` and `unrollLoopHeuristic` can use compiler heuristics to automatically determine the unroll factor. If possible, that is if no CanonicalLoopInfo is required to pass to another method, metadata for LLVM's LoopUnrollPass is added. Otherwise the unroll factor is determined using the same heurstics as user by LoopUnrollPass. Not requiring a CanonicalLoopInfo, especially with `unrollLoopHeuristic` allows greater flexibility.

With full unrolling and partial unrolling with known unroll factor, instead of duplicating instructions by the OpenMPIRBuilder, the full unroll is still delegated to the LoopUnrollPass. In case of partial unrolling the loop is first tiled using the existing `tileLoops` methods, then the inner loop fully unrolled using the same mechanism.

Reviewed By: jdoerfert, kiranchandramohan

Differential Revision: https://reviews.llvm.org/D107764
2021-09-04 19:18:58 -05:00
Roman Lebedev 50634deaa5
Revert "[OpenMP][OpenMPIRBuilder] Implement loop unrolling."
Breaks build with -DBUILD_SHARED_LIBS=ON
```
CMake Error: The inter-target dependency graph contains the following strongly connected component (cycle):
  "LLVMFrontendOpenMP" of type SHARED_LIBRARY
    depends on "LLVMPasses" (weak)
  "LLVMipo" of type SHARED_LIBRARY
    depends on "LLVMFrontendOpenMP" (weak)
  "LLVMCoroutines" of type SHARED_LIBRARY
    depends on "LLVMipo" (weak)
  "LLVMPasses" of type SHARED_LIBRARY
    depends on "LLVMCoroutines" (weak)
    depends on "LLVMipo" (weak)
At least one of these targets is not a STATIC_LIBRARY.  Cyclic dependencies are allowed only among static libraries.
CMake Generate step failed.  Build files cannot be regenerated correctly.
```

This reverts commit 707ce34b06.
2021-09-02 12:42:23 +03:00
Michael Kruse 707ce34b06 [OpenMP][OpenMPIRBuilder] Implement loop unrolling.
Add methods for loop unrolling to the OpenMPIRBuilder class and use them in Clang if `-fopenmp-enable-irbuilder` is enabled. The unrolling methods are:

 * `unrollLoopFull`
 * `unrollLoopPartial`
 * `unrollLoopHeuristic`

`unrollLoopPartial` and `unrollLoopHeuristic` can use compiler heuristics to automatically determine the unroll factor. If possible, that is if no CanonicalLoopInfo is required to pass to another method, metadata for LLVM's LoopUnrollPass is added. Otherwise the unroll factor is determined using the same heurstics as user by LoopUnrollPass. Not requiring a CanonicalLoopInfo, especially with `unrollLoopHeuristic` allows greater flexibility.

With full unrolling and partial unrolling with known unroll factor, instead of duplicating instructions by the OpenMPIRBuilder, the full unroll is still delegated to the LoopUnrollPass. In case of partial unrolling the loop is first tiled using the existing `tileLoops` methods, then the inner loop fully unrolled using the same mechanism.

Reviewed By: jdoerfert, kiranchandramohan

Differential Revision: https://reviews.llvm.org/D107764
2021-09-02 02:37:25 -05:00