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llvm-project/llvm/test/Transforms/GlobalOpt/pr21191.ll

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GlobalOpt: Don't drop unused memberes of a Comdat A linkonce_odr member of a COMDAT shouldn't be dropped if we need to keep the entire COMDAT group. This fixes PR21191. llvm-svn: 219283
2014-10-08 15:23:31 +08:00
; RUN: opt < %s -globalopt -S | FileCheck %s
$c = comdat any
; CHECK: $c = comdat any
Change the .ll syntax for comdats and add a syntactic sugar. In order to make comdats always explicit in the IR, we decided to make the syntax a bit more compact for the case of a GlobalObject in a comdat with the same name. Just dropping the $name causes problems for @foo = globabl i32 0, comdat $bar = comdat ... and declare void @foo() comdat $bar = comdat ... So the syntax is changed to @g1 = globabl i32 0, comdat($c1) @g2 = globabl i32 0, comdat and declare void @foo() comdat($c1) declare void @foo() comdat llvm-svn: 225302
2015-01-07 06:55:16 +08:00
define linkonce_odr void @foo() comdat($c) {
GlobalOpt: Don't drop unused memberes of a Comdat A linkonce_odr member of a COMDAT shouldn't be dropped if we need to keep the entire COMDAT group. This fixes PR21191. llvm-svn: 219283
2014-10-08 15:23:31 +08:00
ret void
}
IR: Introduce local_unnamed_addr attribute. If a local_unnamed_addr attribute is attached to a global, the address is known to be insignificant within the module. It is distinct from the existing unnamed_addr attribute in that it only describes a local property of the module rather than a global property of the symbol. This attribute is intended to be used by the code generator and LTO to allow the linker to decide whether the global needs to be in the symbol table. It is possible to exclude a global from the symbol table if three things are true: - This attribute is present on every instance of the global (which means that the normal rule that the global must have a unique address can be broken without being observable by the program by performing comparisons against the global's address) - The global has linkonce_odr linkage (which means that each linkage unit must have its own copy of the global if it requires one, and the copy in each linkage unit must be the same) - It is a constant or a function (which means that the program cannot observe that the unique-address rule has been broken by writing to the global) Although this attribute could in principle be computed from the module contents, LTO clients (i.e. linkers) will normally need to be able to compute this property as part of symbol resolution, and it would be inefficient to materialize every module just to compute it. See: http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160509/356401.html http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160516/356738.html for earlier discussion. Part of the fix for PR27553. Differential Revision: http://reviews.llvm.org/D20348 llvm-svn: 272709
2016-06-15 05:01:22 +08:00
; CHECK: define linkonce_odr void @foo() local_unnamed_addr comdat($c)
GlobalOpt: Don't drop unused memberes of a Comdat A linkonce_odr member of a COMDAT shouldn't be dropped if we need to keep the entire COMDAT group. This fixes PR21191. llvm-svn: 219283
2014-10-08 15:23:31 +08:00
Change the .ll syntax for comdats and add a syntactic sugar. In order to make comdats always explicit in the IR, we decided to make the syntax a bit more compact for the case of a GlobalObject in a comdat with the same name. Just dropping the $name causes problems for @foo = globabl i32 0, comdat $bar = comdat ... and declare void @foo() comdat $bar = comdat ... So the syntax is changed to @g1 = globabl i32 0, comdat($c1) @g2 = globabl i32 0, comdat and declare void @foo() comdat($c1) declare void @foo() comdat llvm-svn: 225302
2015-01-07 06:55:16 +08:00
define linkonce_odr void @bar() comdat($c) {
GlobalOpt: Don't drop unused memberes of a Comdat A linkonce_odr member of a COMDAT shouldn't be dropped if we need to keep the entire COMDAT group. This fixes PR21191. llvm-svn: 219283
2014-10-08 15:23:31 +08:00
ret void
}
IR: Introduce local_unnamed_addr attribute. If a local_unnamed_addr attribute is attached to a global, the address is known to be insignificant within the module. It is distinct from the existing unnamed_addr attribute in that it only describes a local property of the module rather than a global property of the symbol. This attribute is intended to be used by the code generator and LTO to allow the linker to decide whether the global needs to be in the symbol table. It is possible to exclude a global from the symbol table if three things are true: - This attribute is present on every instance of the global (which means that the normal rule that the global must have a unique address can be broken without being observable by the program by performing comparisons against the global's address) - The global has linkonce_odr linkage (which means that each linkage unit must have its own copy of the global if it requires one, and the copy in each linkage unit must be the same) - It is a constant or a function (which means that the program cannot observe that the unique-address rule has been broken by writing to the global) Although this attribute could in principle be computed from the module contents, LTO clients (i.e. linkers) will normally need to be able to compute this property as part of symbol resolution, and it would be inefficient to materialize every module just to compute it. See: http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160509/356401.html http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160516/356738.html for earlier discussion. Part of the fix for PR27553. Differential Revision: http://reviews.llvm.org/D20348 llvm-svn: 272709
2016-06-15 05:01:22 +08:00
; CHECK: define linkonce_odr void @bar() local_unnamed_addr comdat($c)
GlobalOpt: Don't drop unused memberes of a Comdat A linkonce_odr member of a COMDAT shouldn't be dropped if we need to keep the entire COMDAT group. This fixes PR21191. llvm-svn: 219283
2014-10-08 15:23:31 +08:00
define void @zed() {
call void @foo()
ret void
}