https://github.com/python/cpython/commit/a0dce37895947a09f3ff97ae33bba703f6a6310c
commit: a0dce37895947a09f3ff97ae33bba703f6a6310c
branch: main
author: Diego Russo <[email protected]>
committer: brandtbucher <[email protected]>
date: 2024-06-18T18:27:02-07:00
summary:
GH-119726: Deduplicate JIT trampolines for out-of-range jumps (GH-120250)
files:
A Misc/NEWS.d/next/Core and
Builtins/2024-06-07-22-54-15.gh-issue-119726.D9EE-o.rst
M Tools/jit/_stencils.py
diff --git a/Misc/NEWS.d/next/Core and
Builtins/2024-06-07-22-54-15.gh-issue-119726.D9EE-o.rst b/Misc/NEWS.d/next/Core
and Builtins/2024-06-07-22-54-15.gh-issue-119726.D9EE-o.rst
new file mode 100644
index 00000000000000..595d8dda25fe1b
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and
Builtins/2024-06-07-22-54-15.gh-issue-119726.D9EE-o.rst
@@ -0,0 +1 @@
+JIT: Re-use trampolines on AArch64 when creating stencils. Patch by Diego Russo
diff --git a/Tools/jit/_stencils.py b/Tools/jit/_stencils.py
index 6e046df3026ae9..c7c5ca1590d601 100644
--- a/Tools/jit/_stencils.py
+++ b/Tools/jit/_stencils.py
@@ -181,6 +181,7 @@ class Stencil:
body: bytearray = dataclasses.field(default_factory=bytearray, init=False)
holes: list[Hole] = dataclasses.field(default_factory=list, init=False)
disassembly: list[str] = dataclasses.field(default_factory=list,
init=False)
+ trampolines: dict[str, int] = dataclasses.field(default_factory=dict,
init=False)
def pad(self, alignment: int) -> None:
"""Pad the stencil to the given alignment."""
@@ -189,14 +190,25 @@ def pad(self, alignment: int) -> None:
self.disassembly.append(f"{offset:x}: {' '.join(['00'] * padding)}")
self.body.extend([0] * padding)
- def emit_aarch64_trampoline(self, hole: Hole) -> None:
+ def emit_aarch64_trampoline(self, hole: Hole, alignment: int) -> None:
"""Even with the large code model, AArch64 Linux insists on 28-bit
jumps."""
- base = len(self.body)
+ assert hole.symbol is not None
+ reuse_trampoline = hole.symbol in self.trampolines
+ if reuse_trampoline:
+ # Re-use the base address of the previously created trampoline
+ base = self.trampolines[hole.symbol]
+ else:
+ self.pad(alignment)
+ base = len(self.body)
where = slice(hole.offset, hole.offset + 4)
instruction = int.from_bytes(self.body[where], sys.byteorder)
instruction &= 0xFC000000
instruction |= ((base - hole.offset) >> 2) & 0x03FFFFFF
self.body[where] = instruction.to_bytes(4, sys.byteorder)
+
+ if reuse_trampoline:
+ return
+
self.disassembly += [
f"{base + 4 * 0:x}: d2800008 mov x8, #0x0",
f"{base + 4 * 0:016x}: R_AARCH64_MOVW_UABS_G0_NC
{hole.symbol}",
@@ -225,6 +237,7 @@ def emit_aarch64_trampoline(self, hole: Hole) -> None:
]
):
self.holes.append(hole.replace(offset=base + 4 * i, kind=kind))
+ self.trampolines[hole.symbol] = base
def remove_jump(self, *, alignment: int = 1) -> None:
"""Remove a zero-length continuation jump, if it exists."""
@@ -300,8 +313,7 @@ def process_relocations(self, *, alignment: int = 1) ->
None:
in {"R_AARCH64_CALL26", "R_AARCH64_JUMP26",
"ARM64_RELOC_BRANCH26"}
and hole.value is HoleValue.ZERO
):
- self.code.pad(alignment)
- self.code.emit_aarch64_trampoline(hole)
+ self.code.emit_aarch64_trampoline(hole, alignment)
self.code.holes.remove(hole)
self.code.remove_jump(alignment=alignment)
self.code.pad(alignment)
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