https://github.com/python/cpython/commit/84512c0e7f4441f060026f4fd9ddb7611fc10de4
commit: 84512c0e7f4441f060026f4fd9ddb7611fc10de4
branch: main
author: Diego Russo <[email protected]>
committer: brandtbucher <[email protected]>
date: 2024-07-03T06:22:21-07:00
summary:
GH-119726: Emit AArch64 trampolines out-of-line (GH-121280)
files:
A Misc/NEWS.d/next/Core and
Builtins/2024-06-28-18-34-49.gh-issue-119726.Fjv_Ab.rst
M Tools/jit/_stencils.py
diff --git a/Misc/NEWS.d/next/Core and
Builtins/2024-06-28-18-34-49.gh-issue-119726.Fjv_Ab.rst b/Misc/NEWS.d/next/Core
and Builtins/2024-06-28-18-34-49.gh-issue-119726.Fjv_Ab.rst
new file mode 100644
index 00000000000000..cf5d61450aa3ae
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and
Builtins/2024-06-28-18-34-49.gh-issue-119726.Fjv_Ab.rst
@@ -0,0 +1,2 @@
+Optimize code layout for calls to C functions from the JIT on AArch64.
+Patch by Diego Russo.
diff --git a/Tools/jit/_stencils.py b/Tools/jit/_stencils.py
index 68eb1d13394170..1c6a9edb39840d 100644
--- a/Tools/jit/_stencils.py
+++ b/Tools/jit/_stencils.py
@@ -184,7 +184,7 @@ 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, alignment: int) -> None:
+ def emit_aarch64_trampoline(self, hole: Hole, alignment: int) -> Hole:
"""Even with the large code model, AArch64 Linux insists on 28-bit
jumps."""
assert hole.symbol is not None
reuse_trampoline = hole.symbol in self.trampolines
@@ -194,14 +194,10 @@ def emit_aarch64_trampoline(self, hole: Hole, alignment:
int) -> None:
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)
+ new_hole = hole.replace(addend=base, symbol=None, value=HoleValue.DATA)
if reuse_trampoline:
- return
+ return new_hole
self.disassembly += [
f"{base + 4 * 0:x}: 58000048 ldr x8, 8",
@@ -219,6 +215,7 @@ def emit_aarch64_trampoline(self, hole: Hole, alignment:
int) -> None:
self.body.extend(code)
self.holes.append(hole.replace(offset=base + 8,
kind="R_AARCH64_ABS64"))
self.trampolines[hole.symbol] = base
+ return new_hole
def remove_jump(self, *, alignment: int = 1) -> None:
"""Remove a zero-length continuation jump, if it exists."""
@@ -294,8 +291,9 @@ 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.emit_aarch64_trampoline(hole, alignment)
+ new_hole = self.data.emit_aarch64_trampoline(hole, alignment)
self.code.holes.remove(hole)
+ self.code.holes.append(new_hole)
self.code.remove_jump(alignment=alignment)
self.code.pad(alignment)
self.data.pad(8)
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