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Symptom

In yklua's LLVM AOT IR, we see stuff like:

getelementptr i8, ptr %394, i64 -67108860

Which is surprising.

Where does -67108860 come from?

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Curated Meta-tracing literature list

This is a curated list of meta-tracing reading material ordered by date.

There's a lot out there about meta-traing (the pypy blog contains hundreds of posts alone), so this isn't an exhaustive list. I've slimed it down using the following loose criteria:

• The article must be about meta-tracing concepts.
• It must be a technical article discussing (for example) design decisions/optimisations/performance trade-offs.
• The article isn't a tutorial for a particular system.

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cd /usr/ports/pobj/pypy-7.3.11/pypy3.9-v7.3.11-src && LD_LIBRARY_PATH=.  LDFLAGS=-L/usr/local/lib  CPPFLAGS=-I/usr/local/include  LD_LIBRARY_PATH=.  PYTHONPATH=/usr/ports/pobj/pypy-7.3.11/pypy3.9
-v7.3.11-src/lib_pypy  ./pypy3.9-c lib_pypy/pypy_tools/build_cffi_imports.py                                                                                                                       
/usr/ports/pobj/pypy-7.3.11/pypy3.9-v7.3.11-src/lib-python/3/hashlib.py:181: RuntimeWarning: The _hashlib module is not available, falling back to a much slower implementation (No module named '_
pypy_openssl')                                                                                                                                                                                     
  warnings.warn("The _hashlib module is not available, falling back "                                                                                                                              
ERROR:root:code for hash blake2b was not fou

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$ LD_LIBRARY_PATH=`pwd`/pypy/goal ./pypy/goal/pypy3.9-c -m compileall ./pypy/lib_pypy
debug: WARNING: Library path not found, using compiled-in sys.path, with
debug: WARNING: sys.prefix = '/usr/ports/pobj/pypy-7.3.11/pypy3.9-v7.3.11-src'
debug: WARNING: Make sure the pypy3 binary is kept inside its tree of files.
debug: WARNING: It is ok to create a symlink to it from somewhere else.
Traceback (most recent call last):
  File "/usr/ports/pobj/pypy-7.3.11/pypy3.9-v7.3.11-src/lib-python/3/runpy.py", line 200, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/usr/ports/pobj/pypy-7.3.11/pypy3.9-v7.3.11-src/lib-python/3/runpy.py", line 87, in _run_code
    exec(code, run_globals)

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arrakis:edd> doas btrace trace.bt 44773
tracing pid 44773
[1671642769235478231 +1671642769235478231]		 tid=313009	 >>>20
[1671642769235482014 +3783]		 tid=313009	 >>>46
[1671642769235516315 +34301]		 tid=313009	 >>>86
[1671642769235464974 +1671642769235464974]		 tid=313009	 <<<4
[1671642769235478799 +13825]		 tid=313009	 <<<20
[1671642769235509958 +31159]		 tid=313009	 <<<46
[1671642769235539757 +23442]		 tid=313009	 >>>119
[1671642769235541846 +2089]		 tid=313009	 >>>103

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00000000000106d0 <sem_destroy@@GLIBC_2.2.5>:
   106d0:       31 c0                   xor    %eax,%eax
   106d2:       c3                      retq   

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Stackmap legalisation

Goal

The goal is to fix llvm/llvm-project#21657

TLDR: Passing illegally-typed live variable operands to

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diff --git a/llvm/include/llvm/CodeGen/ISDOpcodes.h b/llvm/include/llvm/CodeGen/ISDOpcodes.h
index ea1d3170acba..531edff27c70 100644
--- a/llvm/include/llvm/CodeGen/ISDOpcodes.h
+++ b/llvm/include/llvm/CodeGen/ISDOpcodes.h
@@ -1269,6 +1269,9 @@ enum NodeType {
 #define BEGIN_REGISTER_VP_SDNODE(VPSDID, ...) VPSDID,
 #include "llvm/IR/VPIntrinsics.def"
 
+  // The `llvm.experimental.stackmap` intrinsic.
+  STACKMAP,

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diff --git a/bin/run_docker_ci_job b/bin/run_docker_ci_job
index bfd5689..4936468 100755
--- a/bin/run_docker_ci_job
+++ b/bin/run_docker_ci_job
@@ -26,13 +26,16 @@ run_image() {
     # Image name must be unique to the buildbot worker so that workers don't clash.
     image_tag=${LOGNAME}-${repo}-${suffix}
 
+    # The container will be run as the worker's "host user". The image is
+    # expected to create a user with the same UID.

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diff --git a/llvm/include/llvm/CodeGen/ISDOpcodes.h b/llvm/include/llvm/CodeGen/ISDOpcodes.h
index ea1d3170acba..531edff27c70 100644
--- a/llvm/include/llvm/CodeGen/ISDOpcodes.h
+++ b/llvm/include/llvm/CodeGen/ISDOpcodes.h
@@ -1269,6 +1269,9 @@ enum NodeType {
 #define BEGIN_REGISTER_VP_SDNODE(VPSDID, ...) VPSDID,
 #include "llvm/IR/VPIntrinsics.def"
 
+  // The `llvm.experimental.stackmap` intrinsic.
+  STACKMAP,