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[IR] Use Min behavior for module flag "PIC Level"

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Using Max for both "PIC Level" and "PIE Level" is inconsistent. PIC imposes less
restriction while PIE imposes more restriction. The result generally
picks the more restrictive behavior: Min for PIC.

This choice matches `ld -r`: a non-pic object and a pic object merge into a
result which should be treated as non-pic.

To allow linking "PIC Level" using Error/Max from old bitcode files, upgrade
Error/Max to Min.

Reviewed By: tejohnson

Differential Revision: https://reviews.llvm.org/D130531
This commit is contained in:
Fangrui Song 2022-08-18 16:28:55 -07:00
parent 37c47b2cac
commit c2a3888793
14 changed files with 56 additions and 38 deletions
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8
clang/test/CodeGen/piclevels.c
View File

@ -4,9 +4,9 @@
// RUN: %clang_cc1 -emit-llvm -pic-level 1 -pic-is-pie %s -o - | FileCheck %s -check-prefix=CHECK-SMALLPIC -check-prefix=CHECK-SMALLPIE
// CHECK-BIGPIC: !llvm.module.flags = !{{{.*}}}
// CHECK-BIGPIC: !{{[0-9]+}} = !{i32 7, !"PIC Level", i32 2}
// CHECK-BIGPIC: ![[#]] = !{i32 8, !"PIC Level", i32 2}
// CHECK-SMALLPIC: !llvm.module.flags = !{{{.*}}}
// CHECK-SMALLPIC: !{{[0-9]+}} = !{i32 7, !"PIC Level", i32 1}
// CHECK-SMALLPIC: ![[#]] = !{i32 8, !"PIC Level", i32 1}
// CHECK-NOPIE-NOT: PIE Level
// CHECK-BIGPIE: !{{[0-9]+}} = !{i32 7, !"PIE Level", i32 2}
// CHECK-SMALLPIE: !{{[0-9]+}} = !{i32 7, !"PIE Level", i32 1}
// CHECK-BIGPIE: ![[#]] = !{i32 7, !"PIE Level", i32 2}
// CHECK-SMALLPIE: ![[#]] = !{i32 7, !"PIE Level", i32 1}

32
llvm/lib/IR/AutoUpgrade.cpp
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@ -4391,26 +4391,34 @@ bool llvm::UpgradeModuleFlags(Module &M) {
MDString *ID = dyn_cast_or_null<MDString>(Op->getOperand(1));
if (!ID)
continue;
auto SetBehavior = [&](Module::ModFlagBehavior B) {
Metadata *Ops[3] = {ConstantAsMetadata::get(ConstantInt::get(
Type::getInt32Ty(M.getContext()), B)),
MDString::get(M.getContext(), ID->getString()),
Op->getOperand(2)};
ModFlags->setOperand(I, MDNode::get(M.getContext(), Ops));
Changed = true;
};
if (ID->getString() == "Objective-C Image Info Version")
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") {
// Upgrade PIC from Error/Max to Min.
if (ID->getString() == "PIC 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;
}
uint64_t V = Behavior->getLimitedValue();
if (V == Module::Error || V == Module::Max)
SetBehavior(Module::Min);
}
}
// Upgrade "PIE Level" from Error to Max.
if (ID->getString() == "PIE Level")
if (auto *Behavior =
mdconst::dyn_extract_or_null<ConstantInt>(Op->getOperand(0)))
if (Behavior->getLimitedValue() == Module::Error)
SetBehavior(Module::Max);
// Upgrade branch protection and return address signing module flags. The
// module flag behavior for these fields were Error and now they are Min.

4
llvm/lib/IR/Module.cpp
View File

@ -596,7 +596,9 @@ PICLevel::Level Module::getPICLevel() const {
}
void Module::setPICLevel(PICLevel::Level PL) {
addModuleFlag(ModFlagBehavior::Max, "PIC Level", PL);
// The merge result of a non-PIC object and a PIC object can only be reliably
// used as a non-PIC object, so use the Min merge behavior.
addModuleFlag(ModFlagBehavior::Min, "PIC Level", PL);
}
PIELevel::Level Module::getPIELevel() const {

2
llvm/test/Bitcode/upgrade-module-flag.ll
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@ -8,7 +8,7 @@
!2 = !{i32 1, !"Objective-C Image Info Version", i32 0}
!3 = !{i32 1, !"Objective-C Image Info Section", !"__DATA, __objc_imageinfo, regular, no_dead_strip"}
; CHECK: !0 = !{i32 7, !"PIC Level", i32 1}
; CHECK: !0 = !{i32 8, !"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 1, !"Objective-C Image Info Section", !"__DATA,__objc_imageinfo,regular,no_dead_strip"}

8
llvm/test/Bitcode/upgrade-pic-level.ll Normal file
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@ -0,0 +1,8 @@
; RUN: llvm-as < %s | llvm-dis | FileCheck %s
; RUN: verify-uselistorder < %s
!llvm.module.flags = !{!0}
; CHECK: !0 = !{i32 8, !"PIC Level", i32 1}
!0 = !{i32 7, !"PIC Level", i32 1}

2
llvm/test/Linker/Inputs/module-flags-pic-2-b.ll
View File

@ -1,4 +1,4 @@
!0 = !{ i32 7, !"PIC Level", i32 2 }
!0 = !{ i32 8, !"PIC Level", i32 2 }
!1 = !{ i32 7, !"PIE Level", i32 2 }
!llvm.module.flags = !{!0, !1}

2
llvm/test/Linker/module-flags-pic-1-a.ll
View File

@ -6,4 +6,4 @@
!llvm.module.flags = !{!0}
; CHECK: !llvm.module.flags = !{!0}
; CHECK: !0 = !{i32 7, !"PIC Level", i32 1}
; CHECK: !0 = !{i32 8, !"PIC Level", i32 1}

4
llvm/test/Linker/module-flags-pic-2-a.ll
View File

@ -2,10 +2,10 @@
; test linking modules with two different PIC and PIE levels
!0 = !{ i32 7, !"PIC Level", i32 1 }
!0 = !{ i32 8, !"PIC Level", i32 1 }
!1 = !{ i32 7, !"PIE Level", i32 1 }
!llvm.module.flags = !{!0, !1}
; CHECK: !0 = !{i32 7, !"PIC Level", i32 2}
; CHECK: !0 = !{i32 8, !"PIC Level", i32 1}
; CHECK: !1 = !{i32 7, !"PIE Level", i32 2}

4
llvm/test/Transforms/Attributor/value-simplify-dbg.ll
View File

@ -58,7 +58,7 @@ declare i32 @speculatable() speculatable readnone
!7 = !{i32 7, !"Dwarf Version", i32 5}
!8 = !{i32 2, !"Debug Info Version", i32 3}
!9 = !{i32 1, !"wchar_size", i32 4}
!10 = !{i32 7, !"PIC Level", i32 2}
!10 = !{i32 8, !"PIC Level", i32 2}
!11 = !{i32 7, !"PIE Level", i32 2}
!12 = !{i32 7, !"uwtable", i32 2}
!13 = !{i32 7, !"frame-pointer", i32 2}
@ -88,7 +88,7 @@ declare i32 @speculatable() speculatable readnone
; CHECK: [[META7:![0-9]+]] = !{i32 7, !"Dwarf Version", i32 5}
; CHECK: [[META8:![0-9]+]] = !{i32 2, !"Debug Info Version", i32 3}
; CHECK: [[META9:![0-9]+]] = !{i32 1, !"wchar_size", i32 4}
; CHECK: [[META10:![0-9]+]] = !{i32 7, !"PIC Level", i32 2}
; CHECK: [[META10:![0-9]+]] = !{i32 8, !"PIC Level", i32 2}
; CHECK: [[META11:![0-9]+]] = !{i32 7, !"PIE Level", i32 2}
; CHECK: [[META12:![0-9]+]] = !{i32 7, !"uwtable", i32 2}
; CHECK: [[META13:![0-9]+]] = !{i32 7, !"frame-pointer", i32 2}

4
llvm/test/Transforms/Attributor/value-simplify-local-remote.ll
View File

@ -769,7 +769,7 @@ entry:
!1 = !{i32 1, !"wchar_size", i32 4}
!2 = !{i32 7, !"openmp", i32 50}
!3 = !{i32 7, !"openmp-device", i32 50}
!4 = !{i32 7, !"PIC Level", i32 2}
!4 = !{i32 8, !"PIC Level", i32 2}
!5 = !{i32 7, !"frame-pointer", i32 2}
!6 = !{i32 7, !"Dwarf Version", i32 2}
!7 = !{i32 2, !"Debug Info Version", i32 3}
@ -795,7 +795,7 @@ entry:
; CHECK: [[META1:![0-9]+]] = !{i32 1, !"wchar_size", i32 4}
; CHECK: [[META2:![0-9]+]] = !{i32 7, !"openmp", i32 50}
; CHECK: [[META3:![0-9]+]] = !{i32 7, !"openmp-device", i32 50}
; CHECK: [[META4:![0-9]+]] = !{i32 7, !"PIC Level", i32 2}
; CHECK: [[META4:![0-9]+]] = !{i32 8, !"PIC Level", i32 2}
; CHECK: [[META5:![0-9]+]] = !{i32 7, !"frame-pointer", i32 2}
; CHECK: [[META6:![0-9]+]] = !{i32 7, !"Dwarf Version", i32 2}
; CHECK: [[META7:![0-9]+]] = !{i32 2, !"Debug Info Version", i32 3}

10
llvm/test/Transforms/OpenMP/spmdization.ll
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@ -2395,7 +2395,7 @@ attributes #11 = { convergent }
!12 = !{i32 1, !"wchar_size", i32 4}
!13 = !{i32 7, !"openmp", i32 50}
!14 = !{i32 7, !"openmp-device", i32 50}
!15 = !{i32 7, !"PIC Level", i32 2}
!15 = !{i32 8, !"PIC Level", i32 2}
!16 = !{i32 7, !"frame-pointer", i32 2}
!17 = !{!"clang version 14.0.0"}
!18 = !{!19, !19, i64 0}
@ -2481,7 +2481,7 @@ attributes #11 = { convergent }
; AMDGPU: [[META12:![0-9]+]] = !{i32 1, !"wchar_size", i32 4}
; AMDGPU: [[META13:![0-9]+]] = !{i32 7, !"openmp", i32 50}
; AMDGPU: [[META14:![0-9]+]] = !{i32 7, !"openmp-device", i32 50}
; AMDGPU: [[META15:![0-9]+]] = !{i32 7, !"PIC Level", i32 2}
; AMDGPU: [[META15:![0-9]+]] = !{i32 8, !"PIC Level", i32 2}
; AMDGPU: [[META16:![0-9]+]] = !{i32 7, !"frame-pointer", i32 2}
; AMDGPU: [[META17:![0-9]+]] = !{!"clang version 14.0.0"}
; AMDGPU: [[TBAA18]] = !{!19, !19, i64 0}
@ -2515,7 +2515,7 @@ attributes #11 = { convergent }
; NVPTX: [[META12:![0-9]+]] = !{i32 1, !"wchar_size", i32 4}
; NVPTX: [[META13:![0-9]+]] = !{i32 7, !"openmp", i32 50}
; NVPTX: [[META14:![0-9]+]] = !{i32 7, !"openmp-device", i32 50}
; NVPTX: [[META15:![0-9]+]] = !{i32 7, !"PIC Level", i32 2}
; NVPTX: [[META15:![0-9]+]] = !{i32 8, !"PIC Level", i32 2}
; NVPTX: [[META16:![0-9]+]] = !{i32 7, !"frame-pointer", i32 2}
; NVPTX: [[META17:![0-9]+]] = !{!"clang version 14.0.0"}
; NVPTX: [[TBAA18]] = !{!19, !19, i64 0}
@ -2549,7 +2549,7 @@ attributes #11 = { convergent }
; AMDGPU-DISABLED: [[META12:![0-9]+]] = !{i32 1, !"wchar_size", i32 4}
; AMDGPU-DISABLED: [[META13:![0-9]+]] = !{i32 7, !"openmp", i32 50}
; AMDGPU-DISABLED: [[META14:![0-9]+]] = !{i32 7, !"openmp-device", i32 50}
; AMDGPU-DISABLED: [[META15:![0-9]+]] = !{i32 7, !"PIC Level", i32 2}
; AMDGPU-DISABLED: [[META15:![0-9]+]] = !{i32 8, !"PIC Level", i32 2}
; AMDGPU-DISABLED: [[META16:![0-9]+]] = !{i32 7, !"frame-pointer", i32 2}
; AMDGPU-DISABLED: [[META17:![0-9]+]] = !{!"clang version 14.0.0"}
; AMDGPU-DISABLED: [[TBAA18]] = !{!19, !19, i64 0}
@ -2583,7 +2583,7 @@ attributes #11 = { convergent }
; NVPTX-DISABLED: [[META12:![0-9]+]] = !{i32 1, !"wchar_size", i32 4}
; NVPTX-DISABLED: [[META13:![0-9]+]] = !{i32 7, !"openmp", i32 50}
; NVPTX-DISABLED: [[META14:![0-9]+]] = !{i32 7, !"openmp-device", i32 50}
; NVPTX-DISABLED: [[META15:![0-9]+]] = !{i32 7, !"PIC Level", i32 2}
; NVPTX-DISABLED: [[META15:![0-9]+]] = !{i32 8, !"PIC Level", i32 2}
; NVPTX-DISABLED: [[META16:![0-9]+]] = !{i32 7, !"frame-pointer", i32 2}
; NVPTX-DISABLED: [[META17:![0-9]+]] = !{!"clang version 14.0.0"}
; NVPTX-DISABLED: [[TBAA18]] = !{!19, !19, i64 0}

4
llvm/test/Transforms/OpenMP/spmdization_assumes.ll
View File

@ -137,7 +137,7 @@ attributes #6 = { convergent nounwind "llvm.assume"="ompx_spmd_amenable" }
!2 = !{i32 1, !"wchar_size", i32 4}
!3 = !{i32 7, !"openmp", i32 50}
!4 = !{i32 7, !"openmp-device", i32 50}
!5 = !{i32 7, !"PIC Level", i32 2}
!5 = !{i32 8, !"PIC Level", i32 2}
!6 = !{i32 7, !"frame-pointer", i32 2}
!7 = !{!"clang version 14.0.0"}
!8 = !{!9, !9, i64 0}
@ -159,7 +159,7 @@ attributes #6 = { convergent nounwind "llvm.assume"="ompx_spmd_amenable" }
; CHECK: [[META2:![0-9]+]] = !{i32 1, !"wchar_size", i32 4}
; CHECK: [[META3:![0-9]+]] = !{i32 7, !"openmp", i32 50}
; CHECK: [[META4:![0-9]+]] = !{i32 7, !"openmp-device", i32 50}
; CHECK: [[META5:![0-9]+]] = !{i32 7, !"PIC Level", i32 2}
; CHECK: [[META5:![0-9]+]] = !{i32 8, !"PIC Level", i32 2}
; CHECK: [[META6:![0-9]+]] = !{i32 7, !"frame-pointer", i32 2}
; CHECK: [[META7:![0-9]+]] = !{!"clang version 14.0.0"}
; CHECK: [[TBAA8]] = !{!9, !9, i64 0}

6
llvm/test/Transforms/OpenMP/spmdization_guarding.ll
View File

@ -381,7 +381,7 @@ attributes #5 = { convergent nounwind "llvm.assume"="omp_no_openmp,ompx_spmd_ame
!2 = !{i32 1, !"wchar_size", i32 4}
!3 = !{i32 7, !"openmp", i32 50}
!4 = !{i32 7, !"openmp-device", i32 50}
!5 = !{i32 7, !"PIC Level", i32 2}
!5 = !{i32 8, !"PIC Level", i32 2}
!6 = !{i32 7, !"frame-pointer", i32 2}
!7 = !{!"clang version 14.0.0"}
!8 = !{!9}
@ -419,7 +419,7 @@ attributes #5 = { convergent nounwind "llvm.assume"="omp_no_openmp,ompx_spmd_ame
; CHECK: [[META2:![0-9]+]] = !{i32 1, !"wchar_size", i32 4}
; CHECK: [[META3:![0-9]+]] = !{i32 7, !"openmp", i32 50}
; CHECK: [[META4:![0-9]+]] = !{i32 7, !"openmp-device", i32 50}
; CHECK: [[META5:![0-9]+]] = !{i32 7, !"PIC Level", i32 2}
; CHECK: [[META5:![0-9]+]] = !{i32 8, !"PIC Level", i32 2}
; CHECK: [[META6:![0-9]+]] = !{i32 7, !"frame-pointer", i32 2}
; CHECK: [[META7:![0-9]+]] = !{!"clang version 14.0.0"}
; CHECK: [[META8:![0-9]+]] = !{!9}
@ -433,7 +433,7 @@ attributes #5 = { convergent nounwind "llvm.assume"="omp_no_openmp,ompx_spmd_ame
; CHECK-DISABLED: [[META2:![0-9]+]] = !{i32 1, !"wchar_size", i32 4}
; CHECK-DISABLED: [[META3:![0-9]+]] = !{i32 7, !"openmp", i32 50}
; CHECK-DISABLED: [[META4:![0-9]+]] = !{i32 7, !"openmp-device", i32 50}
; CHECK-DISABLED: [[META5:![0-9]+]] = !{i32 7, !"PIC Level", i32 2}
; CHECK-DISABLED: [[META5:![0-9]+]] = !{i32 8, !"PIC Level", i32 2}
; CHECK-DISABLED: [[META6:![0-9]+]] = !{i32 7, !"frame-pointer", i32 2}
; CHECK-DISABLED: [[META7:![0-9]+]] = !{!"clang version 14.0.0"}
; CHECK-DISABLED: [[META8:![0-9]+]] = !{!9}

4
llvm/test/Transforms/OpenMP/spmdization_guarding_two_reaching_kernels.ll
View File

@ -265,7 +265,7 @@ attributes #5 = { convergent }
!4 = !{i32 1, !"wchar_size", i32 4}
!5 = !{i32 7, !"openmp", i32 50}
!6 = !{i32 7, !"openmp-device", i32 50}
!7 = !{i32 7, !"PIC Level", i32 2}
!7 = !{i32 8, !"PIC Level", i32 2}
!8 = !{i32 7, !"frame-pointer", i32 2}
!9 = !{!"clang version 14.0.0"}
;.
@ -285,7 +285,7 @@ attributes #5 = { convergent }
; CHECK: [[META4:![0-9]+]] = !{i32 1, !"wchar_size", i32 4}
; CHECK: [[META5:![0-9]+]] = !{i32 7, !"openmp", i32 50}
; CHECK: [[META6:![0-9]+]] = !{i32 7, !"openmp-device", i32 50}
; CHECK: [[META7:![0-9]+]] = !{i32 7, !"PIC Level", i32 2}
; CHECK: [[META7:![0-9]+]] = !{i32 8, !"PIC Level", i32 2}
; CHECK: [[META8:![0-9]+]] = !{i32 7, !"frame-pointer", i32 2}
; CHECK: [[META9:![0-9]+]] = !{!"clang version 14.0.0"}
;.