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cmd/asm: cannot assemble return jump #23838

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cherrymui opened this issue Feb 15, 2018 · 1 comment
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cmd/asm: cannot assemble return jump #23838

cherrymui opened this issue Feb 15, 2018 · 1 comment
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@cherrymui
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The compiler generates return jump using RET instruction with the target in Prog.To. Currently it is not possible to write such instruction in assembly. On many architectures the assembler accepts it but misassembles it.

With (return jump from function with a frame)

TEXT	f(SB),4,$8
	CALL	f1(SB)
	RET	f2(SB)

AMD64: reject with invalid instruction MOVQ f2+8(SP), BP
ARM: assemble to MOVW.P f2+12(R13), R15; ...
ARM64: reject with invalid instruction MOVD.P f2+16(RSP), R30
MIPS: assemble to MOVW f2(R29), R4; ...
PPC64: assemble to MOVD f2(R1), R31; ...
S390X: assemble to MOVD f2(R15), R14; ...

None of them are right.

I will send a CL.
@cherrymui cherrymui self-assigned this Feb 15, 2018
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Change https://golang.org/cl/94175 mentions this issue: cmd/asm: fix assembling return jump

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