forked from OSchip/llvm-project
ELF: Do not create multiple thunks for the same virtual address.
This avoids creating multiple thunks for symbols with aliases or which belong to ICF'd sections. This patch reduces the size of Chromium for Android by 260KB (0.8% of .text). Differential Revision: https://reviews.llvm.org/D44284 llvm-svn: 327154
This commit is contained in:
Peter Collingbourne
parent
a7cb31123c
commit
04ff122632
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@ -1240,17 +1240,22 @@ ThunkSection *ThunkCreator::addThunkSection(OutputSection *OS,
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std::pair<Thunk *, bool> ThunkCreator::getThunk(Symbol &Sym, RelType Type,
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uint64_t Src) {
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auto Res = ThunkedSymbols.insert({&Sym, std::vector<Thunk *>()});
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if (!Res.second) {
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// Check existing Thunks for Sym to see if they can be reused
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for (Thunk *ET : Res.first->second)
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if (ET->isCompatibleWith(Type) &&
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Target->inBranchRange(Type, Src, ET->ThunkSym->getVA()))
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return std::make_pair(ET, false);
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}
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std::vector<Thunk *> *ThunkVec = nullptr;
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// We use (section, offset) pair to find the thunk position if possible so
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// that we create only one thunk for aliased symbols or ICFed sections.
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if (auto *D = dyn_cast<Defined>(&Sym))
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if (!D->isInPlt() && D->Section)
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ThunkVec = &ThunkedSymbolsBySection[{D->Section->Repl, D->Value}];
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if (!ThunkVec)
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ThunkVec = &ThunkedSymbols[&Sym];
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// Check existing Thunks for Sym to see if they can be reused
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for (Thunk *ET : *ThunkVec)
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if (ET->isCompatibleWith(Type) &&
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Target->inBranchRange(Type, Src, ET->ThunkSym->getVA()))
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return std::make_pair(ET, false);
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// No existing compatible Thunk in range, create a new one
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Thunk *T = addThunk(Type, Sym);
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Res.first->second.push_back(T);
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ThunkVec->push_back(T);
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return std::make_pair(T, true);
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}
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@ -21,7 +21,7 @@ class Symbol;
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class InputSection;
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class InputSectionBase;
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class OutputSection;
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class OutputSection;
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class SectionBase;
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// Represents a relocation type, such as R_X86_64_PC32 or R_ARM_THM_CALL.
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typedef uint32_t RelType;
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@ -161,6 +161,8 @@ private:
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bool normalizeExistingThunk(Relocation &Rel, uint64_t Src);
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// Record all the available Thunks for a Symbol
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llvm::DenseMap<std::pair<SectionBase *, uint64_t>, std::vector<Thunk *>>
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ThunkedSymbolsBySection;
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llvm::DenseMap<Symbol *, std::vector<Thunk *>> ThunkedSymbols;
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// Find a Thunk from the Thunks symbol definition, we can use this to find
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@ -1,12 +1,12 @@
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// REQUIRES: arm
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// RUN: llvm-mc -filetype=obj -triple=thumbv7a-none-linux-gnueabi %s -o %t
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// RUN: ld.lld %t --shared -o %t.so
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// RUN: ld.lld %t --shared --icf=all -o %t.so
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// The output file is large, most of it zeroes. We dissassemble only the
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// parts we need to speed up the test and avoid a large output file
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// RUN: llvm-objdump -d %t.so -start-address=8388608 -stop-address=8388624 -triple=thumbv7a-linux-gnueabihf | FileCheck -check-prefix=CHECK1 %s
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// RUN: llvm-objdump -d %t.so -start-address=16777216 -stop-address=16777256 -triple=thumbv7a-linux-gnueabihf | FileCheck -check-prefix=CHECK2 %s
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// RUN: llvm-objdump -d %t.so -start-address=25165824 -stop-address=25165828 -triple=thumbv7a-linux-gnueabihf | FileCheck -check-prefix=CHECK3 %s
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// RUN: llvm-objdump -d %t.so -start-address=25165828 -stop-address=25165924 -triple=armv7a-linux-gnueabihf | FileCheck -check-prefix=CHECK4 %s
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// RUN: llvm-objdump -d %t.so -start-address=0x2000000 -stop-address=0x2000018 -triple=thumbv7a-linux-gnueabihf | FileCheck -check-prefix=CHECK1 %s
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// RUN: llvm-objdump -d %t.so -start-address=0x2800004 -stop-address=0x2800034 -triple=thumbv7a-linux-gnueabihf | FileCheck -check-prefix=CHECK2 %s
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// RUN: llvm-objdump -d %t.so -start-address=0x4000000 -stop-address=0x4000010 -triple=thumbv7a-linux-gnueabihf | FileCheck -check-prefix=CHECK3 %s
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// RUN: llvm-objdump -d %t.so -start-address=0x4000010 -stop-address=0x4000100 -triple=armv7a-linux-gnueabihf | FileCheck -check-prefix=CHECK4 %s
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.syntax unified
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.thumb
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@ -19,74 +19,96 @@
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.type preemptible, %function
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.global far_preemptible
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.type far_preemptible, %function
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.global far_nonpreemptible
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.hidden far_nonpreemptible
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.type far_nonpreemptible, %function
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.global far_nonpreemptible_alias
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.hidden far_nonpreemptible_alias
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.type far_nonpreemptible_alias, %function
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sym1:
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bl elsewhere
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bl preemptible
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bx lr
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preemptible:
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bl far_preemptible
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bl far_nonpreemptible
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bl far_nonpreemptible_alias
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bx lr
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// CHECK1: Disassembly of section .text:
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// CHECK1-NEXT: sym1:
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// CHECK1-NEXT: 800000: 00 f0 00 d8 bl #8388608
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// CHECK1-NEXT: 800004: 00 f0 04 d8 bl #8388616
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// CHECK1-NEXT: 800008: 70 47 bx lr
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// CHECK1-NEXT: 2000000: 00 f0 00 d8 bl #8388608
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// CHECK1-NEXT: 2000004: 00 f0 04 d8 bl #8388616
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// CHECK1-NEXT: 2000008: 70 47 bx lr
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// CHECK1: preemptible:
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// CHECK1-NEXT: 80000a: 00 f0 07 d8 bl #8388622
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// CHECK1-NEXT: 80000e: 70 47 bx lr
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// CHECK1-NEXT: 200000a: 00 f0 07 d8 bl #8388622
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// CHECK1-NEXT: 200000e: 00 f0 0b d8 bl #8388630
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// CHECK1-NEXT: 2000012: 00 f0 09 d8 bl #8388626
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// CHECK1-NEXT: 2000016: 70 47 bx lr
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.section .text.2, "ax", %progbits
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.balign 0x0800000
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bx lr
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// CHECK2: __ThumbV7PILongThunk_elsewhere:
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// CHECK2-NEXT: 1000004: 40 f2 20 0c movw r12, #32
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// CHECK2-NEXT: 1000008: c0 f2 80 0c movt r12, #128
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// CHECK2-NEXT: 100000c: fc 44 add r12, pc
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// CHECK2-NEXT: 100000e: 60 47 bx r12
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// CHECK2-NEXT: 2800004: 40 f2 20 0c movw r12, #32
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// CHECK2-NEXT: 2800008: c0 f2 80 1c movt r12, #384
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// CHECK2-NEXT: 280000c: fc 44 add r12, pc
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// CHECK2-NEXT: 280000e: 60 47 bx r12
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// CHECK2: __ThumbV7PILongThunk_preemptible:
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// CHECK2-NEXT: 1000010: 40 f2 24 0c movw r12, #36
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// CHECK2-NEXT: 1000014: c0 f2 80 0c movt r12, #128
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// CHECK2-NEXT: 1000018: fc 44 add r12, pc
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// CHECK2-NEXT: 100001a: 60 47 bx r12
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// CHECK2-NEXT: 2800010: 40 f2 24 0c movw r12, #36
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// CHECK2-NEXT: 2800014: c0 f2 80 1c movt r12, #384
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// CHECK2-NEXT: 2800018: fc 44 add r12, pc
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// CHECK2-NEXT: 280001a: 60 47 bx r12
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// CHECK2: __ThumbV7PILongThunk_far_preemptible:
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// CHECK2-NEXT: 100001c: 40 f2 28 0c movw r12, #40
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// CHECK2-NEXT: 1000020: c0 f2 80 0c movt r12, #128
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// CHECK2-NEXT: 1000024: fc 44 add r12, pc
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// CHECK2-NEXT: 1000026: 60 47 bx r12
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// CHECK2-NEXT: 280001c: 40 f2 28 0c movw r12, #40
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// CHECK2-NEXT: 2800020: c0 f2 80 1c movt r12, #384
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// CHECK2-NEXT: 2800024: fc 44 add r12, pc
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// CHECK2-NEXT: 2800026: 60 47 bx r12
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// CHECK2: __ThumbV7PILongThunk_far_nonpreemptible:
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// CHECK2-NEXT: 2800028: 4f f6 cd 7c movw r12, #65485
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// CHECK2-NEXT: 280002c: c0 f2 7f 1c movt r12, #383
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// CHECK2-NEXT: 2800030: fc 44 add r12, pc
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// CHECK2-NEXT: 2800032: 60 47 bx r12
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.section .text.3, "ax", %progbits
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.balign 0x0800000
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.balign 0x2000000
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far_preemptible:
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far_nonpreemptible:
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bl elsewhere
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.section .text.4, "ax", %progbits
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.balign 0x2000000
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far_nonpreemptible_alias:
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bl elsewhere
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// CHECK3: far_preemptible:
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// CHECK3: 1800000: 00 f0 16 e8 blx #44
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// CHECK3: 4000000: 00 f0 16 e8 blx #44
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// CHECK4: Disassembly of section .plt:
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// CHECK4-NEXT: $a:
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// CHECK4-NEXT: 1800010: 04 e0 2d e5 str lr, [sp, #-4]!
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// CHECK4-NEXT: 1800014: 00 e6 8f e2 add lr, pc, #0, #12
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// CHECK4-NEXT: 1800018: 00 ea 8e e2 add lr, lr, #0, #20
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// CHECK4-NEXT: 180001c: ec ff be e5 ldr pc, [lr, #4076]!
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// CHECK4-NEXT: 4000010: 04 e0 2d e5 str lr, [sp, #-4]!
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// CHECK4-NEXT: 4000014: 00 e6 8f e2 add lr, pc, #0, #12
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// CHECK4-NEXT: 4000018: 00 ea 8e e2 add lr, lr, #0, #20
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// CHECK4-NEXT: 400001c: ec ff be e5 ldr pc, [lr, #4076]!
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// CHECK4: $d:
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// CHECK4-NEXT: 1800020: d4 d4 d4 d4 .word 0xd4d4d4d4
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// CHECK4-NEXT: 1800024: d4 d4 d4 d4 .word 0xd4d4d4d4
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// CHECK4-NEXT: 1800028: d4 d4 d4 d4 .word 0xd4d4d4d4
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// CHECK4-NEXT: 180002c: d4 d4 d4 d4 .word 0xd4d4d4d4
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// CHECK4-NEXT: 4000020: d4 d4 d4 d4 .word 0xd4d4d4d4
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// CHECK4-NEXT: 4000024: d4 d4 d4 d4 .word 0xd4d4d4d4
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// CHECK4-NEXT: 4000028: d4 d4 d4 d4 .word 0xd4d4d4d4
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// CHECK4-NEXT: 400002c: d4 d4 d4 d4 .word 0xd4d4d4d4
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// CHECK4: $a:
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// CHECK4-NEXT: 1800030: 00 c6 8f e2 add r12, pc, #0, #12
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// CHECK4-NEXT: 1800034: 00 ca 8c e2 add r12, r12, #0, #20
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// CHECK4-NEXT: 1800038: d4 ff bc e5 ldr pc, [r12, #4052]!
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// CHECK4-NEXT: 4000030: 00 c6 8f e2 add r12, pc, #0, #12
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// CHECK4-NEXT: 4000034: 00 ca 8c e2 add r12, r12, #0, #20
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// CHECK4-NEXT: 4000038: d4 ff bc e5 ldr pc, [r12, #4052]!
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// CHECK4: $d:
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// CHECK4-NEXT: 180003c: d4 d4 d4 d4 .word 0xd4d4d4d4
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// CHECK4-NEXT: 400003c: d4 d4 d4 d4 .word 0xd4d4d4d4
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// CHECK4: $a:
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// CHECK4-NEXT: 1800040: 00 c6 8f e2 add r12, pc, #0, #12
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// CHECK4-NEXT: 1800044: 00 ca 8c e2 add r12, r12, #0, #20
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// CHECK4-NEXT: 1800048: c8 ff bc e5 ldr pc, [r12, #4040]!
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// CHECK4-NEXT: 4000040: 00 c6 8f e2 add r12, pc, #0, #12
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// CHECK4-NEXT: 4000044: 00 ca 8c e2 add r12, r12, #0, #20
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// CHECK4-NEXT: 4000048: c8 ff bc e5 ldr pc, [r12, #4040]!
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// CHECK4: $d:
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// CHECK4-NEXT: 180004c: d4 d4 d4 d4 .word 0xd4d4d4d4
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// CHECK4-NEXT: 400004c: d4 d4 d4 d4 .word 0xd4d4d4d4
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// CHECK4: $a:
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// CHECK4-NEXT: 1800050: 00 c6 8f e2 add r12, pc, #0, #12
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// CHECK4-NEXT: 1800054: 00 ca 8c e2 add r12, r12, #0, #20
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// CHECK4-NEXT: 1800058: bc ff bc e5 ldr pc, [r12, #4028]!
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// CHECK4-NEXT: 4000050: 00 c6 8f e2 add r12, pc, #0, #12
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// CHECK4-NEXT: 4000054: 00 ca 8c e2 add r12, r12, #0, #20
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// CHECK4-NEXT: 4000058: bc ff bc e5 ldr pc, [r12, #4028]!
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// CHECK4: $d:
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// CHECK4-NEXT: 180005c: d4 d4 d4 d4 .word 0xd4d4d4d4
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// CHECK4-NEXT: 400005c: d4 d4 d4 d4 .word 0xd4d4d4d4
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