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Update CreateAndExperiment.md #32
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CreateAnExperiment.md
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- Pick a good name for your experiment and create branch for it in dotnet/runtimelab. | ||
- If the experiment is expected to require changes of .NET runtime itself, it should be branched off of [dotnet/runtimelab:runtime-master](https://github.com/dotnet/runtimelab/tree/runtime-master) that is manually maitained mirror of [dotnet/runtime:master](https://github.com/dotnet/runtime/tree/master) branch. |
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These will need to be updated for the master->main rename once it happens.
CreateAnExperiment.md
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- Pick a good name for your experiment and create branch for it in dotnet/runtimelab. | ||
- If the experiment is expected to require changes of .NET runtime itself, it should be branched off of [dotnet/runtimelab:runtime-master](https://github.com/dotnet/runtimelab/tree/runtime-master) that is manually maitained mirror of [dotnet/runtime:master](https://github.com/dotnet/runtime/tree/master) branch. |
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is manually -> "is a manually"
CreateAnExperiment.md
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- Submit a PR to update the [README.MD](https://github.com/dotnet/runtimelab/blob/master/README.md#active-experimental-projects) with the name of your branch and a brief description of the experiment. (Example: [#19](https://github.com/dotnet/runtimelab/pull/19/files)) | ||
- Create label `area-<your experiment name>` for tagging issues. The label should use color `#d4c5f9`. | ||
- If you experiment is branched from dotnet/runtime: |
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If you experiment -> "If your experiment"
Commit migrated from dotnet/runtimelab@4072ab9
…(#63598) * Fix native frame unwind in syscall on arm64 for VS4Mac crash report. Add arm64 version of StepWithCompactNoEncoding for syscall leaf node wrappers that have compact encoding of 0. Fix ReadCompactEncodingRegister so it actually decrements the addr. Change StepWithCompactEncodingArm64 to match what MacOS libunwind does for framed and frameless stepping. arm64 can have frames with the same SP (but different IPs). Increment SP for this condition so createdump's unwind loop doesn't break out on the "SP not increasing" check and the frames are added to the thread frame list in the correct order. Add getting the unwind info for tail called functions like this: __ZL14PROCEndProcessPvji: 36630: f6 57 bd a9 stp x22, x21, [sp, #-48]! 36634: f4 4f 01 a9 stp x20, x19, [sp, #16] 36638: fd 7b 02 a9 stp x29, x30, [sp, #32] 3663c: fd 83 00 91 add x29, sp, #32 ... 367ac: e9 01 80 52 mov w9, #15 367b0: 7f 3e 02 71 cmp w19, #143 367b4: 20 01 88 1a csel w0, w9, w8, eq 367b8: 2e 00 00 94 bl _PROCAbort _TerminateProcess: -> 367bc: 22 00 80 52 mov w2, #1 367c0: 9c ff ff 17 b __ZL14PROCEndProcessPvji The IP (367bc) returns the (incorrect) frameless encoding with nothing on the stack (uses an incorrect LR to unwind). To fix this get the unwind info for PC -1 which points to PROCEndProcess with the correct unwind info. This matches how lldb unwinds this frame. Always address module segment to IP lookup list instead of checking the module regions. Strip pointer authentication bits on PC/LR.
# Local heap optimizations on Arm64 1. When not required to zero the allocated space for local heap (for sizes up to 64 bytes) - do not emit zeroing sequence. Instead do stack probing and adjust stack pointer: ```diff - stp xzr, xzr, [sp,#-16]! - stp xzr, xzr, [sp,#-16]! - stp xzr, xzr, [sp,#-16]! - stp xzr, xzr, [sp,#-16]! + ldr wzr, [sp],#-64 ``` 2. For sizes less than one `PAGE_SIZE` use `ldr wzr, [sp], #-amount` that does probing at `[sp]` and allocates the space at the same time. This saves one instruction for such local heap allocations: ```diff - ldr wzr, [sp] - sub sp, sp, #208 + ldr wzr, [sp],#-208 ``` Use `ldp tmpReg, xzr, [sp], #-amount` when the offset not encodable by post-index variant of `ldr`: ```diff - ldr wzr, [sp] - sub sp, sp, #512 + ldp x0, xzr, [sp],#-512 ``` 3. Allow non-loop zeroing (i.e. unrolled sequence) for sizes up to 128 bytes (i.e. up to `LCLHEAP_UNROLL_LIMIT`). This frees up two internal integer registers for such cases: ```diff - mov w11, #128 - ;; bbWeight=0.50 PerfScore 0.25 -G_M44913_IG19: ; gcrefRegs=00F9 {x0 x3 x4 x5 x6 x7}, byrefRegs=0000 {}, byref, isz stp xzr, xzr, [sp,#-16]! - subs x11, x11, #16 - bne G_M44913_IG19 + stp xzr, xzr, [sp,#-112]! + stp xzr, xzr, [sp,#16] + stp xzr, xzr, [sp,#32] + stp xzr, xzr, [sp,#48] + stp xzr, xzr, [sp,#64] + stp xzr, xzr, [sp,#80] + stp xzr, xzr, [sp,#96] ``` 4. Do zeroing in ascending order of the effective address: ```diff - mov w7, #96 -G_M49279_IG13: stp xzr, xzr, [sp,#-16]! - subs x7, x7, #16 - bne G_M49279_IG13 + stp xzr, xzr, [sp,#-80]! + stp xzr, xzr, [sp,#16] + stp xzr, xzr, [sp,#32] + stp xzr, xzr, [sp,#48] + stp xzr, xzr, [sp,#64] ``` In the example, the zeroing is done at `[initialSp-16], [initialSp-96], [initialSp-80], [initialSp-64], [initialSp-48], [initialSp-32]` addresses. The idea here is to allow a CPU to detect the sequential `memset` to `0` pattern and switch into write streaming mode.
* Support Arm64 "constructed" constants in SuperPMI asm diffs SuperPMI asm diffs tries to ignore constants that can change between multiple replays, such as addresses that the replay engine must generate and not simply hand back from the collected data. Often, addresses have associated relocations generated during replay. SuperPMI can use these relocations to adjust the constants to allow two replays to match. However, there are cases on Arm64 where an address both doesn't report a relocation and is "constructed" using multiple `mov`/`movk` instructions. One case is the `allocPgoInstrumentationBySchema()` API which returns a pointer to a PGO data buffer. An address within this buffer is constructed via a sequence such as: ``` mov x0, #63408 movk x0, #23602, lsl dotnet#16 movk x0, dotnet#606, lsl dotnet#32 ``` When SuperPMI replays this API, it constructs a new buffer and returns that pointer, which is used to construct various actual addresses that are generated as "constructed" constants, shown above. This change "de-constructs" the constants and looks them up in the replay address map. If base and diff match the mapped constants, there is no asm diff. * Fix 32-bit build I don't think we fully support 64-bit replay on 32-bit host, but this fix at least makes it possible for this case. * Support more general mov/movk sequence Allow JIT1 and JIT2 to have a different sequence of mov/movk[/movk[/movk]] that map to the same address in the address map. That is, the replay constant might require a different set of instructions (e.g., if a `movk` is missing because its constant is zero).
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