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Diffstat (limited to 'docs')
| -rw-r--r-- | docs/chapter-backports.md | 48 |
1 files changed, 39 insertions, 9 deletions
diff --git a/docs/chapter-backports.md b/docs/chapter-backports.md index ec6a727a..4b549771 100644 --- a/docs/chapter-backports.md +++ b/docs/chapter-backports.md @@ -361,15 +361,6 @@ lines beyond the original extraction. suite passes, including its current String programs. -- **Chapter 21 synthetic TOP return allocation.** The original compiler at - `f01ee052` and the memory port both fail in `Coalesce.coalesce`: a Split of - TOP has no input live range. Reproduction: `struct S { int x; int y; }; - S !a=new S; if(arg) while(1) { a.x+=arg; a.y+=a.x; } return a.x+a.y;` - through Encoding on x86/SystemV. The new memory regression checks both - precise slices of the synthetic exit, then schedules all three targets; - allocation of its scalar TOP arm remains separate work. Do not hide the - missing live range with a null guard in coalescing. - - **Existing Chapter 18 floating-array assertion.** The unchanged `TypeStruct.makeAry` assertion accepts integers and nullable references but excludes TypeFloat; `return new flt[1];` fails under `-ea`. The Chapter 18 @@ -565,6 +556,45 @@ The top-level runner accepts explicit chapter lists, e.g. ## Validation record +- **Function loop-tree boundaries, Chapters 18-25.** Stop the post-order loop + walk at Return, seed each function's outer tree before visiting its body, and + use that tree for synthetic exit projections, return Regions and the parent + of otherwise exitless loops. In Chapter 25, walking through Return/StopCU/Stop + into Start mistook the external-world cycle for another loop: the function + entry had depth 1 while its return Region retained depth 0. Function bodies + now consistently have depth 0, with real loops adding depth. Chapters 18-20 + also assign the tree to the newly created Never and both projections. + `Chapter18Test.testNeverExitLoopDepth`, forwarded through 25, covers single, + multiple, unconditional and nested synthetic exits. The RISC-V pointer-store + reproducer `Chapter25Test.testNeverReturnPointerRiscV` now runs through + Encoding without changing the spill heuristic or eight-round limit; its + `@Ignore` is removed. Baseline failures are recorded in + `build/loop-tree18-baseline.log` and `build/loop-tree25-baseline.log`. + Full Make suites pass in `build/loop-tree-all.log`: 18 **333+1**, 19 **377+1**, + 20 **399+1**, 21 **438+1**, 22 **459+1**, 23 **481+1**, 24 **511+1**, and + 25 **403+39+9+23+1+14**, plus shared printer/ISA tests. Spill goldens remain + unchanged. + +- **Synthetic TOP returns, Chapters 20-25.** TOP remains neutral in the type + merge but has no runtime register value. BuildLRG excludes TOP definitions + and Phi inputs; IFG does not propagate TOP arms into predecessor liveness; + spilling ignores TOP for loop depth and inserts no copies for it. Chapter + 20's register-bias walk also stops when a Phi arm has no LRG. Coalesce keeps + its normal requirement that both ends of a real copy have live ranges. + `Chapter20Test.testAllocatorTopPhi` checks either Phi slot in scheduled graphs + from Chapter 20 onward. Source regressions in 21-25 (where loop repair precedes + instruction selection) cover integer, non-null pointer and floating returns, + multiple synthetic exits, no real exit, and the original two-field memory + reproducer. Existing `testNeverMemory` tests now continue through Encoding. + Full Make suites pass: 20 **398+1**, 21 **437+1**, 22 **458+1**, 23 **480+1**, + 24 **510+1**, and 25 **402+39+9+22+1+14**, plus shared printer/ISA tests. + Spill goldens were unchanged. The RISC-V pointer-store convergence test was + ignored in that run; the subsequent loop-tree correction above enables it. + Chapter 21 ARM/RISC-V execution + of the original reproducer returns 0 for `arg=0` and stays in the loop for + 10,000 instructions for `arg=1`. Logs: `build/top-ra-all.log` (20-24 and + shared modules), `build/top-ra25-final.log`, `build/top-ra-execution.log`. + - **GCM conditional-writer ordering, Chapters 21-25.** Restored the `idom()` walk from a writer's late block through its early bound, including matching memory-Phi predecessor paths. Chapters 11-20 already retained this walk. |