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[IR] AutoUpgrade ModuleFlagBehavior for PIC and PIE level

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Summary:
From r303590, ModuleFlagBehavior for PIC and PIE level is changed from
Error to Max. This will cause bitcode compatibility issue when linking
against a bitcode static archive built with old compiler.
Add an auto-ugprade path to upgrade the the ModuleFlagBehavior in the
old bitcode to match the new one so IRLinker can link them.

Reviewers: tejohnson, mehdi_amini, dexonsmith

Reviewed By: dexonsmith

Subscribers: hans, llvm-commits

Differential Revision: https://reviews.llvm.org/D36556

llvm-svn: 311387
This commit is contained in:
Steven Wu 2017-08-21 21:49:13 +00:00
parent f241c0c2b9
commit aecde19935
3 changed files with 33 additions and 11 deletions
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28
lib/IR/AutoUpgrade.cpp
View File

@ -2284,14 +2284,14 @@ bool llvm::UpgradeDebugInfo(Module &M) {
}
bool llvm::UpgradeModuleFlags(Module &M) {
const NamedMDNode *ModFlags = M.getModuleFlagsMetadata();
NamedMDNode *ModFlags = M.getModuleFlagsMetadata();
if (!ModFlags)
return false;
bool HasObjCFlag = false, HasClassProperties = false;
bool HasObjCFlag = false, HasClassProperties = false, Changed = false;
for (unsigned I = 0, E = ModFlags->getNumOperands(); I != E; ++I) {
MDNode *Op = ModFlags->getOperand(I);
if (Op->getNumOperands() < 2)
if (Op->getNumOperands() != 3)
continue;
MDString *ID = dyn_cast_or_null<MDString>(Op->getOperand(1));
if (!ID)
@ -2300,7 +2300,24 @@ bool llvm::UpgradeModuleFlags(Module &M) {
HasObjCFlag = true;
if (ID->getString() == "Objective-C Class Properties")
HasClassProperties = true;
// Upgrade PIC/PIE Module Flags. The module flag behavior for these two
// field was Error and now they are Max.
if (ID->getString() == "PIC Level" || ID->getString() == "PIE Level") {
if (auto *Behavior =
mdconst::dyn_extract_or_null<ConstantInt>(Op->getOperand(0))) {
if (Behavior->getLimitedValue() == Module::Error) {
Type *Int32Ty = Type::getInt32Ty(M.getContext());
Metadata *Ops[3] = {
ConstantAsMetadata::get(ConstantInt::get(Int32Ty, Module::Max)),
MDString::get(M.getContext(), ID->getString()),
Op->getOperand(2)};
ModFlags->setOperand(I, MDNode::get(M.getContext(), Ops));
Changed = true;
}
}
}
}
// "Objective-C Class Properties" is recently added for Objective-C. We
// upgrade ObjC bitcodes to contain a "Objective-C Class Properties" module
// flag of value 0, so we can correclty downgrade this flag when trying to
@ -2309,9 +2326,10 @@ bool llvm::UpgradeModuleFlags(Module &M) {
if (HasObjCFlag && !HasClassProperties) {
M.addModuleFlag(llvm::Module::Override, "Objective-C Class Properties",
(uint32_t)0);
return true;
Changed = true;
}
return false;
return Changed;
}
static bool isOldLoopArgument(Metadata *MD) {

12
test/Bitcode/upgrade-module-flag.ll
View File

@ -1,9 +1,13 @@
; RUN: llvm-as < %s | llvm-dis | FileCheck %s
; RUN: verify-uselistorder < %s
!llvm.module.flags = !{!0}
!llvm.module.flags = !{!0, !1, !2}
!0 = !{i32 1, !"Objective-C Image Info Version", i32 0}
!0 = !{i32 1, !"PIC Level", i32 1}
!1 = !{i32 1, !"PIE Level", i32 1}
!2 = !{i32 1, !"Objective-C Image Info Version", i32 0}
; CHECK: !0 = !{i32 1, !"Objective-C Image Info Version", i32 0}
; CHECK: !1 = !{i32 4, !"Objective-C Class Properties", i32 0}
; CHECK: !0 = !{i32 7, !"PIC Level", i32 1}
; CHECK: !1 = !{i32 7, !"PIE Level", i32 1}
; CHECK: !2 = !{i32 1, !"Objective-C Image Info Version", i32 0}
; CHECK: !3 = !{i32 4, !"Objective-C Class Properties", i32 0}

4
test/Linker/module-flags-pic-1-a.ll
View File

@ -2,8 +2,8 @@
; test linking modules with specified and default PIC levels
!0 = !{ i32 1, !"PIC Level", i32 1 }
!0 = !{ i32 7, !"PIC Level", i32 1 }
!llvm.module.flags = !{!0}
; CHECK: !llvm.module.flags = !{!0}
; CHECK: !0 = !{i32 1, !"PIC Level", i32 1}
; CHECK: !0 = !{i32 7, !"PIC Level", i32 1}