Taichi

Highlights:
- **Bug fixes**
- Fix compiler error when flattening if(0) and if(1) (1613) (by **xumingkuan**)
- **Documentation**
- Update documentations on autodiff (1550) (by **彭于斌**)
- **Error messages**
- Improve error message when using non-global variables in global operations (1606) (by **彭于斌**)
- **Examples**
- Add comet.py and fix to_numpy() on sparse matrix fields (1583) (by **彭于斌**)
- **GUI**
- Support gui.lines for batched line drawing (1603) (by **彭于斌**)
- **Infrastructure**
- Add "ti.profiler" (PythonProfiler) for intuitive Python-scope profiling (1493) (by **彭于斌**)
- **IPython and other shells**
- 'ti.sync()' is no longer needed for 'print()' in OpenGL and Metal backend (1546) (by **彭于斌**)

Full changelog:
- [misc] Revert 1493 (1622) (by **Taichi Gardener**)
- [misc] Revert 1550 (1621) (by **Taichi Gardener**)
- [Doc] [autodiff] Update documentations on autodiff (1550) (by **彭于斌**)
- [Example] Add comet.py and fix to_numpy() on sparse matrix fields (1583) (by **彭于斌**)
- [misc] [refactor] 'ti.vec' and 'ti.veci' is deprecated, directly use a tuple in GUI system instead (1605) (by **彭于斌**)
- [doc] Workflow for writing a Python test for 1462 (1475) (by **彭于斌**)
- [Infra] Add "ti.profiler" (PythonProfiler) for intuitive Python-scope profiling (1493) (by **彭于斌**)
- [test] [refactor] Add ti.test decorators to unify testing infrastructure (1462) (by **彭于斌**)
- [async] Compute offloaded IR hash once and cache it (1608) (by **Ye Kuang**)
- [Bug] [opt] Fix compiler error when flattening if(0) and if(1) (1613) (by **xumingkuan**)
- [IPython] 'ti.sync()' is no longer needed for 'print()' in OpenGL and Metal backend (1546) (by **彭于斌**)
- [Error] Improve error message when using non-global variables in global operations (1606) (by **彭于斌**)
- [GUI] Support gui.lines for batched line drawing (1603) (by **彭于斌**)

Highlights:
- **OpenGL backend**
- Support ti.block_dim as block size hint (1602) (by **彭于斌**)
- Support TLS to improve reduction performance (1574) (by **彭于斌**)

Full changelog:
- [OpenGL] [perf] Support ti.block_dim as block size hint (1602) (by **彭于斌**)
- [opengl] [refactor] Fix TLS not working and refactor ParallelSize for grid-stride-loop (1600) (by **彭于斌**)
- [async] Demote struct-fors in async compilation (1593) (by **Ye Kuang**)
- [ir] Make sure "StmtFieldManager" to be correct if we modify some fields after the ctor (1587) (by **Xuanda Yang**)
- [ipython] [refactor] Misc tweaks to make 1308 easier to review (1584) (by **彭于斌**)
- [OpenGL] [perf] Support TLS to improve reduction performance (1574) (by **彭于斌**)

Highlights:
- **Language and syntax**
- Support SNode trailing bits (1558) (by **Yuanming Hu**)
- **OpenGL backend**
- Support 'ti.asm' to insert embed GLSL codes (experimental) (1573) (by **彭于斌**)
- **Performance improvements**
- Improve CUDA runtime performance with warp-level primitives (1571) (by **Yuanming Hu**)

Full changelog:
- [cuda] [bug] Fix a CUDA codegen bug (1592) (by **Yuanming Hu**)
- [test] Fix issues in "bls_particle_grid" tests caused by float-point errors (1590) (by **Yuanming Hu**)
- [llvm] Fix LLVM runtime sparse computation issues (1582) (by **Yuanming Hu**)
- [OpenGL] Support 'ti.asm' to insert embed GLSL codes (experimental) (1573) (by **彭于斌**)
- [example] Upgrade mpm88 to new syntax (1581) (by **彭于斌**)
- [gui] [error] [linux] Better error message when X display not available (1575) (by **彭于斌**)
- [test] Skip mpm88 async on Appveyor (1566) (by **Ye Kuang**)
- [Perf] Improve CUDA runtime performance with warp-level primitives (1571) (by **Yuanming Hu**)
- [async] Fuse tasks only if they are either from the same kernel or arg-less (1530) (by **Ye Kuang**)
- [cc] Support ActionRecorder in C backend (1559) (by **彭于斌**)
- [metal] Plug in the SNodeRep structs into codegen (1480) (by **Ye Kuang**)
- [Lang] Support SNode trailing bits (1558) (by **Yuanming Hu**)

Highlights:
- **CUDA backend**
- Upgrade to PTX 6.3 and add a few CUDA intrinsics (1548) (by **Yuanming Hu**)
- **Performance improvements**
- Improve dynamic listgen and access performance (1547) (by **Yuanming Hu**)
- **Refactor**
- 'ti.Matrix(n, m, dt, shape)' is deprecated, use 'ti.Matrix.var(n, m, dt, shape)' instead (1531) (by **彭于斌**)

Full changelog:
- [cc] The C backend is now capable of running mpm128 (1553) (by **彭于斌**)
- [bug] Update mpm_lagrangian_force and fix Matrix constructor (1545) (by **Ye Kuang**)
- [opengl] [refactor] KernelParallelAttribs -> ParallelSize + virtual methods to make a way for grid-stride-loop (1540) (by **彭于斌**)
- [opengl] Fix reversed nested for loops error on OpenGL (1554) (by **彭于斌**)
- [Perf] Improve dynamic listgen and access performance (1547) (by **Yuanming Hu**)
- [cuda] [llvm] Module broken is TI_WARN instead of TI_ERROR (1557) (by **彭于斌**)
- [linux] Fix LLVM symbol leakage in release mode by using RTLD_GLOBAL (1544) (by **彭于斌**)
- [CUDA] Upgrade to PTX 6.3 and add a few CUDA intrinsics (1548) (by **Yuanming Hu**)
- [ir] Move struct-for demotion pass after offload pass (1541) (by **Ye Kuang**)
- [cc] Support "range for" and "while" statement on C backend (1536) (by **彭于斌**)
- [refactor] Better import order by using \_\_all\_\_ (1510) (by **彭于斌**)
- [misc] Add is_path_all_dense to SNode (1538) (by **Ye Kuang**)
- [Refactor] 'ti.Matrix(n, m, dt, shape)' is deprecated, use 'ti.Matrix.var(n, m, dt, shape)' instead (1531) (by **彭于斌**)
- [lang] [refactor] Setup a multipass AST transformer (1467) (by **彭于斌**)

Highlights:
- **Bug fixes**
- Fix environment variable TI_ARCH=xxx not work (1528) (by **彭于斌**)
- **CUDA backend**
- Use CUDA launch bound to limit register usage (1516) (by **Yuanming Hu**)
- Format CUDA assertions and access out-of-bound errors on the host (1509) (by **Yuanming Hu**)
- **Examples**
- Add FEM elastic simulator: fem99 and fem128 (1521) (by **彭于斌**)
- Add ad_gravity.py (compute gradient from potential energy) (1522) (by **彭于斌**)
- Enhance nbody_oscillator.py with molecular force (1529) (by **彭于斌**)
- **GUI**
- Support gui.triangles() for batched triangle painting (1520) (by **彭于斌**)
- **Language and syntax**
- Enhance warning system and support runtime assert message (1492) (by **彭于斌**)
- Support "break" and "continue" in static-fors (1496) (by **彭于斌**)
- Support (a if cond else b) syntax in Taichi-scope (1468) (by **彭于斌**)
- Make block local storage support coordinate offsets and improve its performance (1497) (by **Yuanming Hu**)
- **Linux**
- Fix LLVM symbol leakage to prevent conflict with libGLX_mesa.so by LD version script (1508) (by **彭于斌**)
- **Performance improvements**
- Make BLS work for MPM (1518) (by **Yuanming Hu**)
- **Refactor**
- Add "ti.field" and "ti.Matrix.field" for future deprecation of "ti.var" (1502) (by **彭于斌**)

Full changelog:
- [Example] [autodiff] Add FEM elastic simulator: fem99 and fem128 (1521) (by **彭于斌**)
- [cuda] Another mutex fix (1534) (by **Yuanming Hu**)
- [opengl] [test] Fix failed OpenGL tests these days (1533) (by **彭于斌**)
- [misc] Prettify KernelProfiler outputs (1525) (by **Yuanming Hu**)
- [Example] [autodiff] Add ad_gravity.py (compute gradient from potential energy) (1522) (by **彭于斌**)
- [cuda] Fix mutex on Turing GPUs (1532) (by **Yuanming Hu**)
- [Bug] [cli] Fix environment variable TI_ARCH=xxx not work (1528) (by **彭于斌**)
- [Example] Enhance nbody_oscillator.py with molecular force (1529) (by **彭于斌**)
- [metal] Introduce SNodeRep_* to be used in the generated SNode structs (1527) (by **Ye Kuang**)
- [test] Fix a typo in test_field.py that caused the failure of CI (1523) (by **Xudong Feng**)
- [bug] Fix dynamic SNode activation (1526) (by **Yuanming Hu**)
- [GUI] Support gui.triangles() for batched triangle painting (1520) (by **彭于斌**)
- [Perf] Make BLS work for MPM (1518) (by **Yuanming Hu**)
- [test] Add test_fuse_dynamic.py to unit test (1513) (by **Ye Kuang**)
- [doc] Update documentaion on meta programming for 1374 (1389) (by **彭于斌**)
- [CUDA] Use CUDA launch bound to limit register usage (1516) (by **Yuanming Hu**)
- [misc] Fix ti.init argument parsing when corresponding environment variable presents (1517) (by **Yuanming Hu**)
- [metal] Fix listgen when iterating over children of bitmasked (1511) (by **Ye Kuang**)
- [test] Fix test_field.py (1514) (by **Yuanming Hu**)
- [Refactor] [lang] Add "ti.field" and "ti.Matrix.field" for future deprecation of "ti.var" (1502) (by **彭于斌**)
- [misc] Update README.md (1512) (by **Yuanming Hu**)
- [Lang] Enhance warning system and support runtime assert message (1492) (by **彭于斌**)
- [CUDA] [llvm] Format CUDA assertions and access out-of-bound errors on the host (1509) (by **Yuanming Hu**)
- [opt] Enable dead instruction elimination for RangeAssumptionStmt (1507) (by **xumingkuan**)
- [Linux] Fix LLVM symbol leakage to prevent conflict with libGLX_mesa.so by LD version script (1508) (by **彭于斌**)
- [cli] Fix "AttributeError" of pytest arguments (1505) (by **xumingkuan**)
- [cli] Remove the never used 'tid' command (1494) (by **彭于斌**)
- [Lang] Support "break" and "continue" in static-fors (1496) (by **彭于斌**)
- [doc] Fix code-block render issue in debugging.rst (1484) (by **彭于斌**)
- [Lang] Support (a if cond else b) syntax in Taichi-scope (1468) (by **彭于斌**)
- [async] Add test_fuse_dense.py to unit tests (1504) (by **Ye Kuang**)
- [Lang] [perf] Make block local storage support coordinate offsets and improve its performance (1497) (by **Yuanming Hu**)
- [metal] Misc tweaks to make 1480 easier to review (1481) (by **Ye Kuang**)

Highlights:
- **Docker**
- Some minor doc fixes and add a docker build badge (1442) (by **Chengchen(Rex) Wang**)
- **Examples**
- Add mass_spring_3d.py (an extension library usage demo) (1386) (by **彭于斌**)
- **Language and syntax**
- Experimental external function call support (1456) (by **xumingkuan**)
- Support ti.assume_in_range (1441) (by **Yuanming Hu**)
- **Miscellaneous**
- Standardize ti.init(), now support log_level, gdb_trigger, advanced_optimization as kwargs (1396) (by **彭于斌**)

Full changelog:
- [metal] Refactor runtime ListManager utils (1444) (by **Ye Kuang**)
- [Lang] Experimental external function call support (1456) (by **xumingkuan**)
- [misc] 'ti.init()' now supports all exported configurations in ti.cfg (1449) (by **彭于斌**)
- [doc] Improve the developer installation documentation (1388) (by **彭于斌**)
- [Example] Add mass_spring_3d.py (an extension library usage demo) (1386) (by **彭于斌**)
- [ir] [refactor] Move alias analysis to a separate file (1446) (by **xumingkuan**)
- [Misc] [cli] Standardize ti.init(), now support log_level, gdb_trigger, advanced_optimization as kwargs (1396) (by **彭于斌**)
- [doc] [Docker] Some minor doc fixes and add a docker build badge (1442) (by **Chengchen(Rex) Wang**)
- [Lang] [ir] Support ti.assume_in_range (1441) (by **Yuanming Hu**)
- [llvm] [mac] Update OS X build bots with prebuilt LLVM 10 (1429) (by **Xuanda Yang**)
- [llvm] Support BLS epilogues (1433) (by **Yuanming Hu**)
- [cc] Setup basic statements & runtime for C backend (1400) (by **彭于斌**)