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48-bit bitwise not emits __snot instead of __i48not #48

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runer112 opened this issue Nov 11, 2024 · 0 comments
Open

48-bit bitwise not emits __snot instead of __i48not #48

runer112 opened this issue Nov 11, 2024 · 0 comments

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@runer112
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runer112 commented Nov 11, 2024 •
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Demonstration: https://discord.com/channels/432891584451706892/1184990251769397380/1305595574246182952

Compiling c -std=gnu11 in -Oz for ez80:

int48_t foo(int48_t x) { return ~x; }
public	_foo
_foo:
	call	__frameset0
	ld	hl, (ix + 6)
	ld	de, (ix + 9)
	call	__snot
	pop	ix
	ret

	extern	__snot
	extern	__frameset0
@runer112 runer112 mentioned this issue Nov 18, 2024
Merged
jacobly0 pushed a commit that referenced this issue Nov 29, 2024
@atrosinenko
[AArch64][PAC] Eliminate excessive MOVs when computing blend (llvm#11…
1fccba5 
…5185)

As function calls do not generally preserve X16 and X17, it is beneficial
to allow AddrDisc operand of BLRA instruction to reside in these
registers and make use of this condition when computing the
discriminator.

This can save up to two MOVs in cases such as loading a (signed) virtual
function pointer via a (signed) pointer to vtable, for example

    ldr   x9, [x16]
    mov   x8, x16
    mov   x17, x8
    movk  x17, llvm#34646, lsl #48
    blraa x9, x17

can be simplified to

    ldr   x8, [x16]
    movk  x16, llvm#34646, lsl #48
    blraa x8, x16
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