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llvm-project/llvm/test/Assembler/ifunc-dsolocal-daig.ll

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Represent runtime preemption in the IR. Currently we do not represent runtime preemption in the IR, which has several drawbacks: 1) The semantics of GlobalValues differ depending on the object file format you are targeting (as well as the relocation-model and -fPIE value). 2) We have no way of disabling inlining of run time interposable functions, since in the IR we only know if a function is link-time interposable. Because of this llvm cannot support elf-interposition semantics. 3) In LTO builds of executables we will have extra knowledge that a symbol resolved to a local definition and can't be preemptable, but have no way to propagate that knowledge through the compiler. This patch adds preemptability specifiers to the IR with the following meaning: dso_local --> means the compiler may assume the symbol will resolve to a definition within the current linkage unit and the symbol may be accessed directly even if the definition is not within this compilation unit. dso_preemptable --> means that the compiler must assume the GlobalValue may be replaced with a definition from outside the current linkage unit at runtime. To ease transitioning dso_preemptable is treated as a 'default' in that low-level codegen will still do the same checks it did previously to see if a symbol should be accessed indirectly. Eventually when IR producers emit the specifiers on all Globalvalues we can change dso_preemptable to mean 'always access indirectly', and remove the current logic. Differential Revision: https://reviews.llvm.org/D20217 llvm-svn: 316668
2017-10-26 23:00:26 +08:00
; RUN: not llvm-as < %s -o /dev/null 2>&1 | FileCheck %s
@foo = dso_local ifunc i32 (i32), i64 ()* @foo_ifunc
; CHECK: error: dso_local is invalid on ifunc
define internal i64 @foo_ifunc() {
entry:
ret i64 0
}