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

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corona10:gh-145742-aarch64
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gh-145742: Fix cross-block adrp+ldr to movz optimization on AArch64#148436
corona10 wants to merge 2 commits intopython:mainfrom
corona10:gh-145742-aarch64

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@corona10 corona10 commented Apr 12, 2026 •
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I found a possible optimization of the current stencil at AArch64 while working on #148217

_LOAD_FAST_r01

// Before (8 instructions):
adrp    x8, __JIT_OPARG_16@GOTPAGE
ldr     x8, [x8, __JIT_OPARG_16@GOTPAGEOFF]
add     x8, x21, w8, uxth #3
ldr     x24, [x8, #0x50]
tbnz    w24, #0x0, ...
ldr     w8, [x24]
add     w8, w8, #0x1
str     w8, [x24]

// After (7 instructions):
movz    x8, #0x0
add     x8, x21, w8, uxth #3
ldr     x24, [x8, #0x50]
tbnz    w24, #0x0, ...
ldr     w8, [x24]
add     w8, w8, #0x1
str     w8, [x24]

_LOAD_FAST_BORROW_r01

// Before (5 instructions):
adrp    x8, __JIT_OPARG_16@GOTPAGE
ldr     x8, [x8, __JIT_OPARG_16@GOTPAGEOFF]
add     x8, x21, w8, uxth #3
ldr     x8, [x8, #0x50]
orr     x24, x8, #0x1

// After (4 instructions):
movz    x8, #0x0
add     x8, x21, w8, uxth #3
ldr     x8, [x8, #0x50]
orr     x24, x8, #0x1

Affected uop codes at AArch64

_CHECK_ATTR_METHOD_LAZY_DICT_r11
_CHECK_ATTR_METHOD_LAZY_DICT_r22
_CHECK_ATTR_METHOD_LAZY_DICT_r33
_COPY_r01
_GUARD_BIT_IS_SET_POP_r00
_GUARD_BIT_IS_SET_POP_r10
_GUARD_BIT_IS_SET_POP_r21
_GUARD_BIT_IS_SET_POP_r32
_GUARD_BIT_IS_UNSET_POP_r00
_GUARD_BIT_IS_UNSET_POP_r10
_GUARD_BIT_IS_UNSET_POP_r21
_GUARD_BIT_IS_UNSET_POP_r32
_GUARD_CODE_VERSION__PUSH_FRAME_r00
_GUARD_CODE_VERSION__PUSH_FRAME_r11
_GUARD_CODE_VERSION__PUSH_FRAME_r22
_GUARD_CODE_VERSION__PUSH_FRAME_r33
_GUARD_TYPE_VERSION_LOCKED_r11
_GUARD_TYPE_VERSION_LOCKED_r22
_GUARD_TYPE_VERSION_LOCKED_r33
_GUARD_TYPE_VERSION_r11
_GUARD_TYPE_VERSION_r22
_GUARD_TYPE_VERSION_r33
_LOAD_COMMON_CONSTANT_r01
_LOAD_COMMON_CONSTANT_r12
_LOAD_COMMON_CONSTANT_r23
_LOAD_CONST_r01
_LOAD_CONST_r12
_LOAD_CONST_r23
_LOAD_FAST_AND_CLEAR_r01
_LOAD_FAST_AND_CLEAR_r12
_LOAD_FAST_AND_CLEAR_r23
_LOAD_FAST_BORROW_r01
_LOAD_FAST_BORROW_r12
_LOAD_FAST_BORROW_r23
_LOAD_FAST_r01
_LOAD_FAST_r12
_LOAD_FAST_r23
_LOAD_SMALL_INT_r01
_LOAD_SMALL_INT_r12
_LOAD_SMALL_INT_r23
_PUSH_NULL_CONDITIONAL_r00
_SAVE_RETURN_OFFSET_r00
_SAVE_RETURN_OFFSET_r11
_SAVE_RETURN_OFFSET_r22
_SAVE_RETURN_OFFSET_r33
_SWAP_FAST_r01
_SWAP_FAST_r11
_SWAP_FAST_r22
_SWAP_FAST_r33
_SWAP_r11

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@corona10 corona10 added the performance Performance or resource usage label Apr 12, 2026
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corona10 commented Apr 12, 2026 •
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cc @diegorusso and @markshannon who work at ARM :)

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