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Recommit "[ThinLTO] Handle GUID collision in import global processing""

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This recommits cc0b9647b76178bc3869bbfff80535ad86366472 which was
reverted in d39d1a2f87aca3cfabe58ecfa5146879baa70096.

I added a fix for an issue found when testing via distributed ThinLTO,
and added a test case for that failure.
This commit is contained in:
Teresa Johnson 2019-11-01 10:31:02 -07:00
parent f5d935c167
commit 16ec00eee7
3 changed files with 68 additions and 5 deletions
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21
llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
View File

@ -239,11 +239,22 @@ void FunctionImportGlobalProcessing::processGlobalForThinLTO(GlobalValue &GV) {
// propagateConstants hasn't been run. We can't internalize GV
// in such case.
if (!GV.isDeclaration() && VI && ImportIndex.withGlobalValueDeadStripping()) {
const auto &SL = VI.getSummaryList();
auto *GVS = SL.empty() ? nullptr : dyn_cast<GlobalVarSummary>(SL[0].get());
// At this stage "maybe" is "definitely"
if (GVS && (GVS->maybeReadOnly() || GVS->maybeWriteOnly()))
cast<GlobalVariable>(&GV)->addAttribute("thinlto-internalize");
if (GlobalVariable *V = dyn_cast<GlobalVariable>(&GV)) {
// We can have more than one local with the same GUID, in the case of
// same-named locals in different but same-named source files that were
// compiled in their respective directories (so the source file name
// and resulting GUID is the same). Find the one in this module.
// Handle the case where there is no summary found in this module. That
// can happen in the distributed ThinLTO backend, because the index only
// contains summaries from the source modules if they are being imported.
// We might have a non-null VI and get here even in that case if the name
// matches one in this module (e.g. weak or appending linkage).
auto* GVS = dyn_cast_or_null<GlobalVarSummary>(
ImportIndex.findSummaryInModule(VI, M.getModuleIdentifier()));
// At this stage "maybe" is "definitely"
if (GVS && (GVS->maybeReadOnly() || GVS->maybeWriteOnly()))
V->addAttribute("thinlto-internalize");
}
}
bool DoPromote = false;

15
llvm/test/ThinLTO/X86/Inputs/guid_collision.ll Normal file
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@ -0,0 +1,15 @@
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-linux-gnu"
; The source for the GUID for this symbol will be -:F
source_filename = "-"
define internal fastcc i64 @F() {
ret i64 0
}
@llvm.global_ctors = appending global [0 x { i32, void ()*, i8* }] zeroinitializer
define i64 @G() {
;%1 = load i32, i32* @dummy2, align 4
ret i64 0
}

37
llvm/test/ThinLTO/X86/guid_collision.ll Normal file
View File

@ -0,0 +1,37 @@
; Make sure LTO succeeds even if %t.bc contains a GlobalVariable F and
; %t2.bc cointains a Function F with the same GUID.
;
; RUN: opt -module-summary %s -o %t.bc
; RUN: opt -module-summary %p/Inputs/guid_collision.ll -o %t2.bc
; RUN: llvm-lto2 run %t.bc %t2.bc -o %t.out -save-temps \
; RUN: -r=%t.bc,H,px -r=%t.bc,G, -r=%t2.bc,G,px
; RUN: llvm-dis -o - %t.out.1.3.import.bc | FileCheck %s
; RUN: llvm-lto2 run %t.bc %t2.bc -o %t.out -thinlto-distributed-indexes \
; RUN: -r=%t.bc,H,px -r=%t.bc,G, -r=%t2.bc,G,px
; RUN: opt -function-import -import-all-index -summary-file %t.bc.thinlto.bc %t.bc -o %t.out
; RUN: llvm-dis -o - %t.out | FileCheck %s
; Sanity check that G was imported
; CHECK: define available_externally i64 @G
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-linux-gnu"
; The source for the GUID for this symbol will be -:F
source_filename = "-"
@F = internal constant i8 0
; Provide a global that has the same name as one from the module we import G
; from, to test handling of a global variable with an entry in the distributed
; index but not with a copy in the source module (since we can't import
; appending linkage globals).
@llvm.global_ctors = appending global [0 x { i32, void ()*, i8* }] zeroinitializer
define i64 @H() {
call i64 @G()
ret i64 0
}
declare i64 @G()