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Move summary dead stripping before regular LTO.

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This way dead stripping results are recorded in combined summary and
can be used in regular LTO passes.

Differential Revision: https://reviews.llvm.org/D33615

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@304577 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evgeniy Stepanov 2017-06-02 18:24:17 +00:00
parent f1a1cf19c1
commit a667b70dbe
2 changed files with 28 additions and 14 deletions
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26
lib/LTO/LTO.cpp
View File

@ -622,6 +622,19 @@ unsigned LTO::getMaxTasks() const {
}
Error LTO::run(AddStreamFn AddStream, NativeObjectCache Cache) {
// Compute "dead" symbols, we don't want to import/export these!
DenseSet<GlobalValue::GUID> GUIDPreservedSymbols;
for (auto &Res : GlobalResolutions) {
if (Res.second.VisibleOutsideThinLTO &&
// IRName will be defined if we have seen the prevailing copy of
// this value. If not, no need to preserve any ThinLTO copies.
!Res.second.IRName.empty())
GUIDPreservedSymbols.insert(GlobalValue::getGUID(
GlobalValue::dropLLVMManglingEscape(Res.second.IRName)));
}
computeDeadSymbols(ThinLTO.CombinedIndex, GUIDPreservedSymbols);
// Save the status of having a regularLTO combined module, as
// this is needed for generating the ThinLTO Task ID, and
// the CombinedModule will be moved at the end of runRegularLTO.
@ -974,19 +987,6 @@ Error LTO::runThinLTO(AddStreamFn AddStream, NativeObjectCache Cache,
StringMap<std::map<GlobalValue::GUID, GlobalValue::LinkageTypes>> ResolvedODR;
if (Conf.OptLevel > 0) {
// Compute "dead" symbols, we don't want to import/export these!
DenseSet<GlobalValue::GUID> GUIDPreservedSymbols;
for (auto &Res : GlobalResolutions) {
if (Res.second.VisibleOutsideThinLTO &&
// IRName will be defined if we have seen the prevailing copy of
// this value. If not, no need to preserve any ThinLTO copies.
!Res.second.IRName.empty())
GUIDPreservedSymbols.insert(GlobalValue::getGUID(
GlobalValue::dropLLVMManglingEscape(Res.second.IRName)));
}
computeDeadSymbols(ThinLTO.CombinedIndex, GUIDPreservedSymbols);
ComputeCrossModuleImport(ThinLTO.CombinedIndex, ModuleToDefinedGVSummaries,
ImportLists, ExportLists);

16
test/ThinLTO/X86/deadstrip.ll
View File

@ -22,6 +22,20 @@
; RUN: llvm-dis < %t.out.1.3.import.bc | FileCheck %s --check-prefix=CHECK2
; RUN: llvm-nm %t.out.1 | FileCheck %s --check-prefix=CHECK2-NM
; RUN: llvm-bcanalyzer -dump %t.out.index.bc | FileCheck %s --check-prefix=COMBINED
; Live, NotEligibleForImport, Internal
; COMBINED-DAG: <COMBINED {{.*}} op2=55
; Live, Internal
; COMBINED-DAG: <COMBINED {{.*}} op2=39
; Live, External
; COMBINED-DAG: <COMBINED {{.*}} op2=32
; COMBINED-DAG: <COMBINED {{.*}} op2=32
; COMBINED-DAG: <COMBINED {{.*}} op2=32
; (Dead)
; COMBINED-DAG: <COMBINED {{.*}} op2=0
; COMBINED-DAG: <COMBINED {{.*}} op2=0
; COMBINED-DAG: <COMBINED {{.*}} op2=0
; Dead-stripping on the index allows to internalize these,
; and limit the import of @baz thanks to early pruning.
; CHECK-NOT: available_externally {{.*}} @baz()
@ -35,7 +49,7 @@
; Make sure we didn't internalize @boo, which is reachable via
; llvm.global_ctors
; CHECK2: define void @boo()
; We should have eventually revoved @baz since it was internalized and unused
; We should have eventually removed @baz since it was internalized and unused
; CHECK2-NM-NOT: _baz
; The final binary should not contain any of the dead functions,