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intel isa: comments to explain rip-relative addressing encoding

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This commit is contained in:
Pat Hickey
2017-12-12 15:13:11 -08:00
committed by Jakob Stoklund Olesen
parent ed81bc21be
commit d444044e9e
2 changed files with 10 additions and 3 deletions
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6
lib/cretonne/meta/isa/intel/recipes.py
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@@ -560,11 +560,11 @@ allones_fnaddr8 = TailRecipe(
got_fnaddr8 = TailRecipe(
'got_fnaddr8', FuncAddr, size=5, ins=(), outs=GPR,
# rex2 is a hack at the moment to get one that sets the `r` bit in rex
# rm for modrm_rm is 5 to get RIP-relative addressing
# rex2 gets passed 0 for r/m register because the upper bit of
# r/m doesnt get decoded when in rip-relative addressing mode.
emit='''
PUT_OP(bits, rex2(0, out_reg0), sink);
modrm_rm(5, out_reg0, sink);
modrm_riprel(out_reg0, sink);
sink.reloc_external(Reloc::IntelGotPCRel4,
&func.dfg.ext_funcs[func_ref].name);
sink.put4(0);