[LLVMdev] [ARM] [PIC] optimizing the loading of hidden global variable (original) (raw)

Rafael Espíndola rafael.espindola at gmail.com
Fri Mar 14 13:48:54 PDT 2014

On 14 March 2014 14:34, Weiming Zhao <weimingz at codeaurora.org> wrote:

Hi Rafael,

Yes, merging gv prevents linker to do garbage collection. Should it be implemented as a peephole pass? If we do it too early, the distance between GVs are not fixed yet.

Correct. It would be somewhere in CodeGen, I am not exactly sure where.

PS: Below is the GCC output with "extern" hidden: ldr r2, .L2 stmfd sp!, {r3, lr} .save {r3, lr} .LPIC0: add r0, pc, r2 bl Z4initPv(PLT) ldr r1, .L2+4 .LPIC1: add r0, pc, r1 bl Z4initPv(PLT) ldr r0, .L2+8 .LPIC2: add r0, pc, r0 ldmfd sp!, {r3, lr} b Z4initPv(PLT) .L3: .align 2 .L2: .word g0-(.LPIC0+8) .word g1-(.LPIC1+8) .word g2-(.LPIC2+8)

That is pretty neat too.

Cheers, Rafael

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