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Sergei Trofimovich authored
Summary: The commit fixes incorrect code generation of integer-gmp package on ia64 due to C prototypes mismatch. Before the patch prototypes for "foreign import prim" were: StgWord poizh[]; After the patch they became: StgFunPtr poizh(); Long story: Consider the following simple example: {-# LANGUAGE MagicHash, GHCForeignImportPrim, UnliftedFFITypes #-} module M where import GHC.Prim -- Int# foreign import prim "poizh" poi# :: Int# -> Int# Before the patch unregisterised build generated the following 'poizh' reference: EI_(poizh); /* StgWord poizh[]; */ FN_(M_poizh_entry) { // ... JMP_((W_)&poizh); } After the patch it looks this way: EF_(poizh); /* StgFunPtr poizh(); */ FN_(M_poizh_entry) { // ... JMP_((W_)&poizh); } On ia64 it leads to different relocation types being generated: incorrect one: addl r14 = @ltoffx(poizh#) ld8.mov r14 = [r14], poizh# ; r14 = address-of 'poizh#' correct one: addl r14 = @ltoff(@fptr(poizh#)), gp ; r14 = address-of-thunk 'poizh#' ld8 r14 = [r14] '@fptr(poizh#)' basically instructs assembler to creates another obect consisting of real address to 'poizh' instructions and module address. That '@fptr' object is used as a function "address" This object is different for every module referencing 'poizh' symbol. All indirect function calls expect '@fptr' object. That way call site reads real destination address and set destination module address in 'gp' register from '@fptr'. Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
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