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Diffstat (limited to 'chapter24/README.md')
| -rw-r--r-- | chapter24/README.md | 24 |
1 files changed, 13 insertions, 11 deletions
diff --git a/chapter24/README.md b/chapter24/README.md index 58e13f39..59a893d9 100644 --- a/chapter24/README.md +++ b/chapter24/README.md @@ -5,10 +5,12 @@ where `score` in the middle does not have to be repeated. The main compiler change is Interprocedural Sparse Conditional Constant Propagation (SCCP): an optimistic type solve which also discovers call-graph -edges. This snapshot still uses the earlier parser/type and memory machinery; -Chapter 25 currently contains the larger incomplete-types SSA redesign and -separate compilation. Independent correctness fixes will move backward first; -see the [backport review queue](../docs/chapter-backports.md). +edges. Memory follows Chapter 10b's lazy partitioning: BulkMemPhi represents +whole memory, MemPhi merges precise aliases, and allocations consume and produce +partial memory for their instance fields. During SCCP, memory Phis ignore +unreachable inputs and allocation results stay high until control reaches them. +Chapter 25 retains the larger incomplete-types SSA redesign, private constructor +memory, and separate compilation; see the [backport review queue](../docs/chapter-backports.md). You can also read [this chapter](https://github.com/SeaOfNodes/Simple/tree/linear-chapter24) in a linear Git revision history on the [linear](https://github.com/SeaOfNodes/Simple/tree/linear) branch and [compare](https://github.com/SeaOfNodes/Simple/compare/linear-chapter23...linear-chapter24) it to the previous chapter. @@ -299,22 +301,22 @@ both the cheaper first attempt and the mandatory fallback. Chapter 21's adjacent-copy forwarding also carries forward: after coloring, a sole use in the next instruction can read the source register when its operand mask permits it and no two-address tie is broken. The table below -includes this cleanup. Cohort 22 now also includes the two zero-move C return +includes this cleanup and the lazy memory forward port. Cohort 22 now also includes the two zero-move C return ABI checks added since the earlier audit (26 entries instead of 24). Run `make spill-stats`. All rows use **Chapter 24's compiler**, optimizer seed 123, and the same source/target combinations as the earlier cohort tables. These Windows results combine x86 SystemV/Win64 and RISC-V/ARM SystemV, -remeasured on 2026-09-28 after the function-pointer lifetime backport. +remeasured after the lazy memory forward port. | Program cohort | Compilations | Retained moves | Loop-weighted moves | |---|---:|---:|---:| -| Chapter 20 | 39 | 319 | 431 | -| Chapter 21 | 52 | 425 | 957 | +| Chapter 20 | 39 | 320 | 439 | +| Chapter 21 | 52 | 420 | 952 | | Chapter 22 | 26 | 67 | 67 | -| Chapter 23 | 30 | 81 | 228 | -| Chapter 24 | 67 | 418 | 1,286 | -| **Total** | **214** | **1,310** | **2,969** | +| Chapter 23 | 30 | 78 | 225 | +| Chapter 24 | 67 | 422 | 1,325 | +| **Total** | **214** | **1,307** | **3,008** | `_spills` counts retained SplitNodes, including register moves. `_spillScaled` weights those moves by `8^loopDepth`; it is a cost estimate, not measured memory |