Taichi

Highlights:
- **The OpenGL Compute Shader backend (by **彭于斌**) is officially released!**
- **Examples**
- Add Multiple Importance Sampling to the cornell box scene (890) (by **Ye Kuang**)
- **IR optimization passes**
- Extract constants to top-level (897) (by **xumingkuan**)
- Global variable optimizations (857) (by **xumingkuan**)

Full changelog:
- [ir] [refactor] Separate `UnaryOpType::cast` into `cast_value` and `cast_bits` (892) (by **彭于斌**)
- [opt] Set `has_global_side_effect` to `false` for some statements (898) (by **xumingkuan**)
- [Example] Add Multiple Importance Sampling to the cornell box scene (890) (by **Ye Kuang**)
- [async] Overlap compilation and execution (885) (by **Yuanming Hu**)
- [Opt] Extract constants to top-level (897) (by **xumingkuan**)
- [ir] Remove `Ident` alias (895) (by **Ye Kuang**)
- [opt] Use advanced_optimization for 857 (894) (by **xumingkuan**)
- [Opt] Global variable optimizations (857) (by **xumingkuan**)

- [Bug] Fix CPU SNode reader in debug mode (887) (by **Yuanming Hu**)
- [opengl] Tolerate all errors in with_opengl() (884) (by **彭于斌**)
- [Opt] [Refactor] [Bug] Use state machines for optimization on variables (859) (by **xumingkuan**)
- [async] No sync after kernel launch and postpone lower access (883) (by **Yuanming Hu**)
- [async] Fix SNode reading in async mode (881) (by **Yuanming Hu**)
- [opt] Eliminate assertions with non-zero const conditions (877) (by **xumingkuan**)
- [misc] Reorganize misc files (876) (by **Yuanming Hu**)
- revert 769 ti.cfg.gdb_trigger error (879) (by **彭于斌**)
- [cuda] [test] Add TI_DEVICE_MEMORY_GB and TI_DEVICE_MEMORY_FRACTION environment variable (769) (by **彭于斌**)
- [OpenGL] Detect driver existence in `with_opengl()` (864) (by **彭于斌**)
- [misc] Avoid unnecessary linking when git commit hash not changed (871) (by **Yuanming Hu**)
- [async] [refactor] Fix async engine statement not found error (874) (by **Yuanming Hu**)
- [example] Fix `pbf2d.py`'s initialization to use np.float32 (873) (by **Ye Kuang**)
- [misc] Avoid mutable defaults in `PyTaichi` (870) (by **Yuxin Wu**)
- [misc] Fix imread not reading properly when image is not equal in height and width (855) (by **彭于斌**)
- [async] Parallel compilation (863) (by **Yuanming Hu**)
- [Opt] [Bug] Fix the state of the last store after a loop (862) (by **xumingkuan**)
- [test] `ti test -na opengl` to exclude tests on some archs (830) (by **彭于斌**)
- [opt] Eliminate useless local stores and atomics (858) (by **xumingkuan**)
- [doc] update documention for 843 (844) (by **彭于斌**)
- [Example] add sdf2d.py (835) (by **彭于斌**)
- [opt] Lower `linearize` even without advanced optimization (854) (by **xumingkuan**)
- [misc] Split accessor and other kernels in statistics (853) (by **xumingkuan**)
- [misc] Profiler now supports multiple threads (852) (by **Yuanming Hu**)
- [opt] Improve optimization for OffsetAndExtractBitsStmt (851) (by **xumingkuan**)
- [Bug] [Opt] Fix a bug in local variable optimization (849) (by **xumingkuan**)
- [test] Fix duplicate test name in `test_tensor_reflection.py` (850) (by **xumingkuan**)
- [Example] Add `quadtree.py` (824) (by **彭于斌**)
- [misc] Avoid printing empty logs (848) (by **xumingkuan**)
- [async] Each JIT thread now has its own LLVM context (845) (by **Yuanming Hu**)
- [misc] Clear stats in the constructor of Program (by **xumingkuan**)
- [Misc] Enhance `ti.init` and support `arch=ti.gpu` (843) (by **彭于斌**)
- [misc] Add an option to print statistics into files (841) (by **xumingkuan**)
- [test] Fix test when `advanced_optimization == false` (842) (by **xumingkuan**)
- [Example] Add a Cornell box renderer (836) (by **Ye Kuang**)
- [metal] Increment by thread grid size for the grid-strip loops (837) (by **Ye Kuang**)
- [OpenGL] Use GLAD as API loader (replace GLEW) (819) (by **彭于斌**)
- [opt] Eliminate `WhileControlStmt` with non-zero const conditions (by **xumingkuan**)
- [refactor] Move backend implementations to the `backends` folder (818) (by **Yuanming Hu**)
- [test] Add a test for statement offloading (826) (by **xumingkuan**)
- [Opt] Algebraic simplification for bitwise operators (827) (by **xumingkuan**)

Highlights:
- **CUDA backend**
- Fix `slim_libdevice.bc` shipping on Windows (820) (by **Yuanming Hu**)
- **OpenGL backend**
- Fix NVIDIA GLSL compile freeze by sorting SNodes (808) (by **彭于斌**)

Full changelog:
- [refactor] Miscellaneous & mechanical cleanups (822) (by **Taichi Gardener**)
- [CUDA] Fix `slim_libdevice.bc` shipping on Windows (820) (by **Yuanming Hu**)
- [OpenGL] Fix NVIDIA GLSL compile freeze by sorting SNodes (808) (by **彭于斌**)
- [refactor] Remove `SNodeAttr` and decouple `SNode` from LLVM (817) (by **Yuanming Hu**)
- [async] Parallel compilation infrastructure (816) (by **Yuanming Hu**)
- [example] Improve `mpm128` gravity control (809) (by **彭于斌**)

Highlights:
- **Bug fixes**
- Insert gc tasks only for `pointer` and `dynamic` SNodes (781) (by **Ye Kuang**)
- **Command line interface**
- Fix `ti` commands other than `ti test` (783) (by **Yuanming Hu**)
- **Documentation**
- Improved documentation (747) (by **彭于斌**)
- **Examples**
- Add an Euler equation solver (796) (by **Kenneth Lozes**)
- **Intermediate representation**
- Fix compilation crash when offloading local variables stores/atomic adds (813) (by **xumingkuan**)
- Fix malformed IRs (806) (by **xumingkuan**)
- **Language and syntax**
- Support matrix initialization with a list of vectors (811) (by **Kenneth Lozes**)
- **LLVM backend (CPU and CUDA)**
- Upgrade to LLVM 10 and keep backward compatibility with LLVM 8 (787) (by **Tao He**)
- **OpenGL backend**
- Support range for-loops with non-constant bounds (785) (by **彭于斌**)
- **IR optimization passes**
- Improve local variable optimizations (788) (by **xumingkuan**)

Full changelog:
- [Lang] Support matrix initialization with a list of vectors (811) (by **Kenneth Lozes**)
- [IR] Fix compilation crash when offloading local variables stores/atomic adds (813) (by **xumingkuan**)
- [opt] Avoid storing constants across offloaded tasks (812) (by **xumingkuan**)
- [misc] Update `README.md` (776) (by **Yuanming Hu**)
- [OpenGL] Support range for-loops with non-constant bounds (785) (by **彭于斌**)
- [Example] Add an Euler equation solver (796) (by **Kenneth Lozes**)
- [doc] Add Google code review article PDFs (800) (by **Yuanming Hu**)
- [IR] Fix malformed IRs (806) (by **xumingkuan**)
- [async] Add parallel task executor (805) (by **Yuanming Hu**)
- [ir] Add checks for `loop_var`s and print names for loops (803) (by **xumingkuan**)
- [Opt] Improve local variable optimizations (788) (by **xumingkuan**)
- [misc] Improve type checking error messages (797) (by **Yuanming Hu**)
- [example] Improve mpm_lagrangian_forces.py (799) (by **Yuanming Hu**)
- [doc] Document the Statistics class (795) (by **Yuanming Hu**)
- [metal] Implement range_for using grid stride loop (780) (by **Ye Kuang**)
- [doc] Include a few links to Google Code Health articles in contributor guidelines (789) (by **Yuanming Hu**)
- [Doc] Improved documentation (747) (by **彭于斌**)
- [LLVM] Upgrade to LLVM 10 and keep backward compatibility with LLVM 8 (787) (by **Tao He**)
- [doc] Fix typo (786) (by **xumingkuan**)
- [CLI] Fix `ti` commands other than `ti test` (783) (by **Yuanming Hu**)
- [Bug] [sparse] Insert gc tasks only for `pointer` and `dynamic` SNodes (781) (by **Ye Kuang**)

Notable changes:
- **Language**
- Support `4x4` matrix inverse and determinant (763) (by **KLozes**)
- **Command-line interface**
- Fix `ti test --arch ...` (764) (by **彭于斌**)
- **Examples**
- Add 2D stable fluids example (748) (by **Ye Kuang**)
- **PyPI package**
- Package name changed from `taichi-nightly` to `taichi` (762) (by **Yuanming Hu**)
- [Full log](https://github.com/taichi-dev/taichi/releases/tag/0.5.12)

Full changelog:
- [cli] Add `TI_GDB_TRIGGER` environment variable (766) (by **彭于斌**)
- [misc] Update Jenkinsfile (by **Yuanming Hu**)
- [cli] Fix `ti test` (774) (by **Yuanming Hu**)
- [misc] Update `README.md` (767) (by **Yuanming Hu**)
- [refactor] [opt] Move LocalLoadSearcher and 2 other classes to irpass::analysis (771) (by **xumingkuan**)
- [ir] [refactor] Slim ir.h and reduce build time by ~4% (761) (by **xumingkuan**)
- [CLI] Fix `ti test --arch ...` (764) (by **彭于斌**)
- [opengl] GLFW 3.3.2 is now included as a submodule (760) (by **Yuanming Hu**)
- [lang] Support 4x4 matrix inverse and determinant (763) (by **KLozes**)
- [PyPI] Package name changed from `taichi-nightly` to `taichi` (762) (by **Yuanming Hu**)
- [misc] Unify include format (759) (by **Taichi Gardener**)
- [Example] Add 2D stable fluids example (748) (by **Ye Kuang**)

Notable changes:
- **Automatic differentiation**
- Fix floating-point type-cast gradients (687) (by **Yuanming Hu**)
- **CUDA backend**
- PyPI package `taichi-nightly` now covers CUDA 10.X on Windows and Linux (756) (by **Yuanming Hu**)
- **Examples**
- Add `game_of_life.py` (741) (by **彭于斌**)
- Fix `examples/regression.py` (757) (by **Quan Wang**)
- **GUI**
- Support SPACE key (749) (by **Ye Kuang**)
- Fix blinking particles and random segmentation faults in `ti.GUI.circles` (755) (by **Yuanming Hu**)
- **Language and syntax**
- Support `continue` on all backends (716) (by **Ye Kuang**)
- **LLVM backend (CPU and CUDA)**
- Fix LLVM struct-for codegen crashing due to extra return 704 (707) (by **Yuanming Hu**)
- **Metal backend**
- Support `ti.random()` on Metal (710) (by **Ye Kuang**)
- **OpenGL backend**
- Support NVIDIA GLSL compiler (666) (by **彭于斌**)
- 64-bit data type support (717) (by **彭于斌**)
- Support more than one external array arguments (694) (by **彭于斌**)
- **IR and Optimization**
- More Taichi IR standardization and optimization (656) (by **xumingkuan**)

Full changelog:
- [CUDA] limit memory allocation chunk size 128 MB (758) (by **Yuanming Hu**)
- [CUDA] PyPI package `taichi-nightly` now covers CUDA 10.X on Windows and Linux (756) (by **Yuanming Hu**)
- [Example] Fix `examples/regression.py` (757) (by **Quan Wang**)
- [ir] [refactor] Move all passes that do not change IR into `irpass::analysis` (754) (by **xumingkuan**)
- [GUI] Fix blinking particles and random segmentation faults in `ti.GUI.circles` (755) (by **Yuanming Hu**)
- [misc] Fix dynamic node out-of-bound checker (752) (by **Yuanming Hu**)
- [doc] Update `syntax.rst` to include `ti.sqrt`, `ti.asin`, `ti.acos` and `x ** y` (753) (by **Quan Wang**)
- [refactor] Remove vprintf in runtime/llvm/runtime.cpp to avoid name conflicts (750) (by **Yuanming Hu**)
- [misc] Update Jenkinsfile (by **Yuanming Hu**)
- [GUI][Metal] Support SPACE key (749) (by **Ye Kuang**)
- [OpenGL] 64-bit data type support (717) (by **彭于斌**)
- [cli] Better `ti test` to test single cpp file and no cpp test when testing python(s) (724) (by **彭于斌**)
- [ir] [refactor] Simplify statement visitors (744) (by **xumingkuan**)
- [async] Benchmark infrastructure (743) (by **Yuanming Hu**)
- [opt] Move common statements in true/false branches outside if's (727) (by **xumingkuan**)
- [opengl] Add `check_opengl_error` to prevent potential segfaults (728) (by **彭于斌**)
- [Example] Add `game_of_life.py` (741) (by **彭于斌**)
- [ir] [refactor] Add a `verify` pass to find out illegal IRs, and remove OffloadedStmt::begin_stmt/end_stmt (731) (by **xumingkuan**)
- [cli] Improve `ti` header message (715) (by **Ye Kuang**)
- [metal][refactor] Use `compile_to_offloads()` in codegen (738) (by **Ye Kuang**)
- [ir] Fix adjoint alloca location in `make_adjoint` (734) (by **Yuanming Hu**)
- [ir] Fix out-of-scope operands during offloading (730) (by **Yuanming Hu**)
- [metal] Refactor the codegen to have multiple code sections (733) (by **Ye Kuang**)
- [ir] [refactor] BasicStmtVisitor includes Frontend sstatements (732) (by **彭于斌**)
- [infra] AppVeyor triggers format server when `[format]` included as substrings in commit messages (725) (by **彭于斌**)
- [opengl] [refactor] Remove the global `no_gc` in `opengl_codegen.cpp` (723) (by **Ye Kuang**)
- [Lang] Support `continue` on all backends (716) (by **Ye Kuang**)
- [ir] Add assertions of `Alloca`s in the constructors of LocalAddress and LocalStoreStmt (by **xumingkuan**)
- [CUDA] Improve CUDA build portability with run-time driver loading (714) (by **Yuanming Hu**)
- [infra] Windows stack backtrace (720) (by **xumingkuan**)
- [ir][refactor] Use const & in function arguments to avoid copying (718) (by **xumingkuan**)
- [opengl] [refactor] Fix memory leakages using modern C++ memory management features (696) (by **彭于斌**)
- [ir] Fix compilation crash when passing global pointer to if statements (713) (by **Yuanming Hu**)
- [test] Make `test_struct_for_branching` run on archs with `pointer` (712) (by **Ye Kuang**)
- [Metal] Support `ti.random()` on Metal (710) (by **Ye Kuang**)
- [refactor] SNode now uses unique_ptr instead of shared_ptr for clearer children ownership (705) (by **Yuanming Hu**)
- [LLVM] Fix LLVM struct-for codegen crashing due to extra return 704 (707) (by **Yuanming Hu**)
- [metal] Skip `listgen` for leaf Snode (699) (by **Ye Kuang**)
- [refactor] CUDA-related infrastructure (706) (by **Yuanming Hu**)
- [OpenGL] Support more than one external array arguments (694) (by **彭于斌**)
- [ir] Add a function to test if two IRNodes are equivalent (683) (by **xumingkuan**)
- [refactor] Create `taichi/codegen/codegen_llvm.cpp` and outline class member definitions (702) (by **Taichi Gardener**)
- [refactor] Extract Taichi IR compilation from KernelCodeGen (700) (by **Yuanming Hu**)
- [async] AsyncEngine infrastructure (698) (by **Yuanming Hu**)
- [metal] Fix tests that require 64-bit data (697) (by **Ye Kuang**)
- [opengl] Improved randomness of PRNGs across each launch (692) (by **彭于斌**)
- [OpenGL] Support NVIDIA GLSL compiler (666) (by **彭于斌**)
- [metal] Fix bug in Metal listgen where it goes beyond the capacity (691) (by **Ye Kuang**)
- [ir] Add statement field manager (690) (by **Yuanming Hu**)
- [misc] Enforce the use of include "taichi/..." (688) (by **Taichi Gardener**)
- [AutoDiff] Fix floating-point type-cast gradients (687) (by **Yuanming Hu**)
- [metal] Use grid-stride loop to implement `listgen` kernels (682) (by **Ye Kuang**)
- [refactor] Remove `llvm::Value *Stmt::value` (686) (by **Yuanming Hu**)
- [refactor] Removed `Stmt::adjoint` (685) (by **Yuanming Hu**)
- [lang] Fix ti.static(ti.grouped(...)) syntax checker (681) (by **xumingkuan**)