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[ThinLTO/gold] ThinLTO internalization fixes

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Internalization was missing cases where we originally had a local symbol
that was promoted eagerly but not actually exported. This is because we
were only internalizing the set of global (non-local) symbols that were
PREVAILAING_DEF_IRONLY. Instead, collect the set of global symbols that
are referenced outside of a single IR file, and skip internalization for
those.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275247 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Teresa Johnson 2016-07-13 03:42:41 +00:00
parent 17c5ce914c
commit 90c5cb8752
3 changed files with 18 additions and 16 deletions
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2
test/tools/gold/X86/thinlto.ll
View File

@ -62,6 +62,8 @@
; BACKEND1-NEXT: </MODULE_STRTAB_BLOCK
; BACKEND1-NEXT: <GLOBALVAL_SUMMARY_BLOCK
; BACKEND1-NEXT: <VERSION
; One of these will be a COMBINED_ORIGINAL_NAME since f can be internalized.
; BACKEND1-NEXT: <COMBINED
; BACKEND1-NEXT: <COMBINED
; BACKEND1-NEXT: <COMBINED
; BACKEND1-NEXT: </GLOBALVAL_SUMMARY_BLOCK

7
test/tools/gold/X86/thinlto_internalize.ll
View File

@ -11,11 +11,18 @@
; f() should be internalized and eliminated after inlining
; CHECK-NOT: @f()
; h() should be internalized after promotion, and eliminated after inlining
; CHECK-NOT: @h.llvm.
target triple = "x86_64-unknown-linux-gnu"
define i32 @g() {
call void @f()
call void @h()
ret i32 0
}
define void @f() {
ret void
}
define internal void @h() {
ret void
}

25
tools/gold/gold-plugin.cpp
View File

@ -1323,10 +1323,9 @@ static ld_plugin_status thinLTOLink(raw_fd_ostream *ApiFile) {
// interfaces with gold.
DenseMap<void *, std::unique_ptr<PluginInputFile>> HandleToInputFile;
// Keep track of internalization candidates as well as those that may not
// be internalized because they are refereneced from other IR modules.
DenseSet<GlobalValue::GUID> Internalize;
DenseSet<GlobalValue::GUID> CrossReferenced;
// Keep track of symbols that must not be internalized because they
// are referenced outside of a single IR module.
DenseSet<GlobalValue::GUID> Preserve;
ModuleSummaryIndex CombinedIndex;
uint64_t NextModuleId = 0;
@ -1352,23 +1351,17 @@ static ld_plugin_status thinLTOLink(raw_fd_ostream *ApiFile) {
if (Index)
CombinedIndex.mergeFrom(std::move(Index), ++NextModuleId);
// Look for internalization candidates based on gold's symbol resolution
// information. Also track symbols referenced from other IR modules.
// Use gold's symbol resolution information to identify symbols referenced
// by more than a single IR module (before importing, which is checked
// separately).
for (auto &Sym : F.syms) {
ld_plugin_symbol_resolution Resolution =
(ld_plugin_symbol_resolution)Sym.resolution;
if (Resolution == LDPR_PREVAILING_DEF_IRONLY)
Internalize.insert(GlobalValue::getGUID(Sym.name));
if (Resolution == LDPR_RESOLVED_IR || Resolution == LDPR_PREEMPTED_IR)
CrossReferenced.insert(GlobalValue::getGUID(Sym.name));
if (Resolution != LDPR_PREVAILING_DEF_IRONLY)
Preserve.insert(GlobalValue::getGUID(Sym.name));
}
}
// Remove symbols referenced from other IR modules from the internalization
// candidate set.
for (auto &S : CrossReferenced)
Internalize.erase(S);
// Collect for each module the list of function it defines (GUID ->
// Summary).
StringMap<std::map<GlobalValue::GUID, GlobalValueSummary *>>
@ -1387,7 +1380,7 @@ static ld_plugin_status thinLTOLink(raw_fd_ostream *ApiFile) {
const auto &ExportList = ExportLists.find(ModuleIdentifier);
return (ExportList != ExportLists.end() &&
ExportList->second.count(GUID)) ||
!Internalize.count(GUID);
Preserve.count(GUID);
};
// Use global summary-based analysis to identify symbols that can be