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[TargetMachine] Move COFF special case for ExternalSymbolSDNode from shouldAssumeDSOLocal to X86Subtarget 

Intended to be NFC. ARM/AArch64 don't appear to need adjustment.

TargetMachine::shouldAssumeDSOLocal is expected to be very simple, ideally
matching isDSOLocal(). The IR producers are expected to set dso_local correctly.
(While some may think this function can make producers' work easier, the
function is really not in a good position to set dso_local. See the various
special cases we duplicate from clang CodeGenModule.cpp.)

Reviewed By: mstorsjo

Differential Revision: https://reviews.llvm.org/D108514
This commit is contained in:
Fangrui Song 2021-08-23 13:54:39 -07:00
parent 4c40c03b39
commit ba6e15d8cc
2 changed files with 8 additions and 6 deletions
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6
llvm/lib/Target/TargetMachine.cpp
View File

@ -101,15 +101,11 @@ bool TargetMachine::shouldAssumeDSOLocal(const Module &M,
// dso_preemptable. At this point in time, the various IR producers
// have not been transitioned to always produce a dso_local when it
// is possible to do so.
// In the case of ExternalSymbolSDNode, GV is null and we should just return
// false. However, COFF currently relies on this to be true
//
// As a result we still have some logic in here to improve the quality of the
// generated code.
// FIXME: Add a module level metadata for whether intrinsics should be assumed
// local.
if (!GV)
return TT.isOSBinFormatCOFF();
return false;
// If the IR producer requested that this GV be treated as dso local, obey.
if (GV->isDSOLocal())

8
llvm/lib/Target/X86/X86Subtarget.cpp
View File

@ -143,6 +143,9 @@ unsigned char X86Subtarget::classifyGlobalReference(const GlobalValue *GV,
return classifyLocalReference(GV);
if (isTargetCOFF()) {
// ExternalSymbolSDNode like _tls_index.
if (!GV)
return X86II::MO_NO_FLAG;
if (GV->hasDLLImportStorageClass())
return X86II::MO_DLLIMPORT;
return X86II::MO_COFFSTUB;
@ -184,10 +187,13 @@ X86Subtarget::classifyGlobalFunctionReference(const GlobalValue *GV,
if (TM.shouldAssumeDSOLocal(M, GV))
return X86II::MO_NO_FLAG;
// Functions on COFF can be non-DSO local for two reasons:
// Functions on COFF can be non-DSO local for three reasons:
// - They are intrinsic functions (!GV)
// - They are marked dllimport
// - They are extern_weak, and a stub is needed
if (isTargetCOFF()) {
if (!GV)
return X86II::MO_NO_FLAG;
if (GV->hasDLLImportStorageClass())
return X86II::MO_DLLIMPORT;
return X86II::MO_COFFSTUB;