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gh-145742: Fix cross-block adrp+ldr to movz optimization on AArch64 #148436

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gh-145742: Fix cross-block adrp+ldr to movz optimization on AArch64 #148436

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gh-145742: Fix cross-block adrp+ldr to movz optimization on AArch64
corona10 Apr 12, 2026
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corona10 Apr 12, 2026
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2026-04-12-20-25-58.gh-issue-145742.R7lf1e.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Fix cross-block adrp+ldr to movz optimization on AArch64. Patch by Donghee
Na.
16 changes: 11 additions & 5 deletions Tools/jit/_optimizers.py
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Original file line number Diff line number Diff line change
Expand Up @@ -499,9 +499,12 @@ def _fixup_constants(self) -> None:
if not self.supports_small_constants:
return
index = 0
# Keep small_const_index across blocks so small constant
# pairs split across block boundaries are still matched.
small_const_index = -1
prev_fixed: list[Instruction] = []
for block in self._blocks():
fixed: list[Instruction] = []
small_const_index = -1
for inst in block.instructions:
if inst.kind == InstructionKind.SMALL_CONST_1:
marker = f"jit_pending_{inst.target}{index}:"
Expand All @@ -513,25 +516,27 @@ def _fixup_constants(self) -> None:
if small_const_index < 0:
fixed.append(inst)
continue
small_const_1 = fixed[small_const_index]
# SMALL_CONST_1 may be in the current or previous block's list.
source = fixed if small_const_index < len(fixed) else prev_fixed
small_const_1 = source[small_const_index]
if not self._small_consts_match(small_const_1, inst):
small_const_index = -1
fixed.append(inst)
continue
assert small_const_1.target is not None
if small_const_1.target.endswith("16"):
fixed[small_const_index] = self._make_temp_label(index)
source[small_const_index] = self._make_temp_label(index)
index += 1
else:
assert small_const_1.target.endswith("32")
patch_kind, replacement = self._small_const_1(small_const_1)
if replacement is not None:
label = f"{self.const_reloc}{patch_kind}_JIT_RELOCATION_CONST{small_const_1.target[:-3]}_JIT_RELOCATION_{index}:"
index += 1
fixed[small_const_index - 1] = Instruction(
source[small_const_index - 1] = Instruction(
InstructionKind.OTHER, "", label, None
)
fixed[small_const_index] = replacement
source[small_const_index] = replacement
patch_kind, replacement = self._small_const_2(inst)
if replacement is not None:
assert inst.target is not None
Expand All @@ -544,6 +549,7 @@ def _fixup_constants(self) -> None:
small_const_index = -1
else:
fixed.append(inst)
prev_fixed = fixed
block.instructions = fixed

def _small_const_1(self, inst: Instruction) -> tuple[str, Instruction | None]:
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