OutStreamer->EmitValue(E, Size);
}
+void ARMAsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
+ if (PromotedGlobals.count(GV))
+ // The global was promoted into a constant pool. It should not be emitted.
+ return;
+ AsmPrinter::EmitGlobalVariable(GV);
+}
+
/// runOnMachineFunction - This uses the EmitInstruction()
/// method to print assembly for each instruction.
///
const Function* F = MF.getFunction();
const TargetMachine& TM = MF.getTarget();
+ // Collect all globals that had their storage promoted to a constant pool.
+ // Functions are emitted before variables, so this accumulates promoted
+ // globals from all functions in PromotedGlobals.
+ for (auto *GV : AFI->getGlobalsPromotedToConstantPool())
+ PromotedGlobals.insert(GV);
+
// Calculate this function's optimization goal.
unsigned OptimizationGoal;
if (F->hasFnAttribute(Attribute::OptimizeNone))
/// -1 if uninitialized, 0 if conflicting goals
int OptimizationGoals;
+ /// List of globals that have had their storage promoted to a constant
+ /// pool. This lives between calls to runOnMachineFunction and collects
+ /// data from every MachineFunction. It is used during doFinalization
+ /// when all non-function globals are emitted.
+ SmallPtrSet<const GlobalVariable*,2> PromotedGlobals;
+
public:
explicit ARMAsmPrinter(TargetMachine &TM,
std::unique_ptr<MCStreamer> Streamer);
void EmitStartOfAsmFile(Module &M) override;
void EmitEndOfAsmFile(Module &M) override;
void EmitXXStructor(const DataLayout &DL, const Constant *CV) override;
-
+ void EmitGlobalVariable(const GlobalVariable *GV) override;
+
// lowerOperand - Convert a MachineOperand into the equivalent MCOperand.
bool lowerOperand(const MachineOperand &MO, MCOperand &MCOp);
STATISTIC(NumTailCalls, "Number of tail calls");
STATISTIC(NumMovwMovt, "Number of GAs materialized with movw + movt");
STATISTIC(NumLoopByVals, "Number of loops generated for byval arguments");
+STATISTIC(NumConstpoolPromoted,
+ "Number of constants with their storage promoted into constant pools");
static cl::opt<bool>
ARMInterworking("arm-interworking", cl::Hidden,
cl::desc("Enable / disable ARM interworking (for debugging only)"),
cl::init(true));
+static cl::opt<bool> EnableConstpoolPromotion(
+ "arm-promote-constant", cl::Hidden,
+ cl::desc("Enable / disable promotion of unnamed_addr constants into "
+ "constant pools"),
+ cl::init(true));
+static cl::opt<unsigned> ConstpoolPromotionMaxSize(
+ "arm-promote-constant-max-size", cl::Hidden,
+ cl::desc("Maximum size of constant to promote into a constant pool"),
+ cl::init(64));
+
namespace {
class ARMCCState : public CCState {
public:
llvm_unreachable("bogus TLS model");
}
+/// Return true if all users of V are within function F, looking through
+/// ConstantExprs.
+static bool allUsersAreInFunction(const Value *V, const Function *F) {
+ SmallVector<const User*,4> Worklist;
+ for (auto *U : V->users())
+ Worklist.push_back(U);
+ while (!Worklist.empty()) {
+ auto *U = Worklist.pop_back_val();
+ if (isa<ConstantExpr>(U)) {
+ for (auto *UU : U->users())
+ Worklist.push_back(UU);
+ continue;
+ }
+
+ auto *I = dyn_cast<Instruction>(U);
+ if (!I || I->getParent()->getParent() != F)
+ return false;
+ }
+ return true;
+}
+
+/// Return true if all users of V are within some (any) function, looking through
+/// ConstantExprs. In other words, are there any global constant users?
+static bool allUsersAreInFunctions(const Value *V) {
+ SmallVector<const User*,4> Worklist;
+ for (auto *U : V->users())
+ Worklist.push_back(U);
+ while (!Worklist.empty()) {
+ auto *U = Worklist.pop_back_val();
+ if (isa<ConstantExpr>(U)) {
+ for (auto *UU : U->users())
+ Worklist.push_back(UU);
+ continue;
+ }
+
+ if (!isa<Instruction>(U))
+ return false;
+ }
+ return true;
+}
+
+static SDValue promoteToConstantPool(const GlobalValue *GV, SelectionDAG &DAG,
+ EVT PtrVT, SDLoc dl) {
+ // If we're creating a pool entry for a constant global with unnamed address,
+ // and the global is small enough, we can emit it inline into the constant pool
+ // to save ourselves an indirection.
+ //
+ // This is a win if the constant is only used in one function (so it doesn't
+ // need to be duplicated) or duplicating the constant wouldn't increase code
+ // size (implying the constant is no larger than 4 bytes).
+ const Function *F = DAG.getMachineFunction().getFunction();
+ auto *GVar = dyn_cast<GlobalVariable>(GV);
+ if (EnableConstpoolPromotion && GVar && GVar->hasInitializer() &&
+ GVar->isConstant() && GVar->hasGlobalUnnamedAddr() && GVar->hasLocalLinkage()) {
+ // The constant islands pass can only really deal with alignment requests
+ // <= 4 bytes and cannot pad constants itself. Therefore we cannot promote
+ // any type wanting greater alignment requirements than 4 bytes. We also
+ // can only promote constants that are multiples of 4 bytes in size or
+ // are paddable to a multiple of 4. Currently we only try and pad constants
+ // that are strings for simplicity.
+ auto *Init = GVar->getInitializer();
+ auto *CDAInit = dyn_cast<ConstantDataArray>(Init);
+ unsigned Size = DAG.getDataLayout().getTypeAllocSize(Init->getType());
+ unsigned Align = DAG.getDataLayout().getABITypeAlignment(Init->getType());
+ unsigned RequiredPadding = 4 - (Size % 4);
+ bool PaddingPossible =
+ RequiredPadding == 4 || (CDAInit && CDAInit->isString());
+
+ if (PaddingPossible && Align <= 4 && Size <= ConstpoolPromotionMaxSize &&
+ (allUsersAreInFunction(GVar, F) ||
+ (Size <= 4 && allUsersAreInFunctions(GVar)))) {
+ if (RequiredPadding != 4) {
+ StringRef S = CDAInit->getAsString();
+
+ SmallVector<uint8_t,16> V(S.size());
+ std::copy(S.bytes_begin(), S.bytes_end(), V.begin());
+ while (RequiredPadding--)
+ V.push_back(0);
+ Init = ConstantDataArray::get(*DAG.getContext(), V);
+ }
+
+ SDValue CPAddr =
+ DAG.getTargetConstantPool(Init, PtrVT, Align);
+
+ MachineFunction &MF = DAG.getMachineFunction();
+ ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
+ AFI->markGlobalAsPromotedToConstantPool(GVar);
+ ++NumConstpoolPromoted;
+ return DAG.getNode(ARMISD::Wrapper, dl, MVT::i32, CPAddr);
+ }
+ }
+ return SDValue();
+}
+
SDValue ARMTargetLowering::LowerGlobalAddressELF(SDValue Op,
SelectionDAG &DAG) const {
EVT PtrVT = getPointerTy(DAG.getDataLayout());
bool IsRO =
(isa<GlobalVariable>(GV) && cast<GlobalVariable>(GV)->isConstant()) ||
isa<Function>(GV);
+
+ if (TM.shouldAssumeDSOLocal(*GV->getParent(), GV))
+ if (SDValue V = promoteToConstantPool(GV, DAG, PtrVT, dl))
+ return V;
+
if (isPositionIndependent()) {
bool UseGOT_PREL = !TM.shouldAssumeDSOLocal(*GV->getParent(), GV);
/// copies.
bool IsSplitCSR;
+ /// Globals that have had their storage promoted into the constant pool.
+ SmallVector<const GlobalVariable*,2> PromotedGlobals;
+
public:
ARMFunctionInfo() :
isThumb(false),
}
return It;
}
+
+ /// Indicate to the backend that \c GV has had its storage changed to inside
+ /// a constant pool. This means it no longer needs to be emitted as a
+ /// global variable.
+ void markGlobalAsPromotedToConstantPool(const GlobalVariable *GV) {
+ PromotedGlobals.push_back(GV);
+ }
+ ArrayRef<const GlobalVariable*> getGlobalsPromotedToConstantPool() {
+ return PromotedGlobals;
+ }
};
} // End llvm namespace
--- /dev/null
+; RUN: llc -relocation-model=static < %s | FileCheck %s
+; RUN: llc -relocation-model=pic < %s | FileCheck %s
+; RUN: llc -relocation-model=ropi < %s | FileCheck %s
+; RUN: llc -relocation-model=rwpi < %s | FileCheck %s
+
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-n32-S64"
+target triple = "armv7--linux-gnueabihf"
+
+@.str = private unnamed_addr constant [2 x i8] c"s\00", align 1
+@.str1 = private unnamed_addr constant [69 x i8] c"this string is far too long to fit in a literal pool by far and away\00", align 1
+@.str2 = private unnamed_addr constant [27 x i8] c"this string is just right!\00", align 1
+@.str3 = private unnamed_addr constant [26 x i8] c"this string is used twice\00", align 1
+@.str4 = private unnamed_addr constant [29 x i8] c"same string in two functions\00", align 1
+@.arr1 = private unnamed_addr constant [2 x i16] [i16 3, i16 4], align 2
+@.arr2 = private unnamed_addr constant [2 x i16] [i16 7, i16 8], align 2
+@.ptr = private unnamed_addr constant [2 x i16*] [i16* getelementptr inbounds ([2 x i16], [2 x i16]* @.arr2, i32 0, i32 0), i16* null], align 2
+
+; CHECK-LABEL: @test1
+; CHECK: adr r0, [[x:.*]]
+; CHECK: [[x]]:
+; CHECK: .asciz "s\000\000"
+define void @test1() #0 {
+ tail call void @a(i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str, i32 0, i32 0)) #2
+ ret void
+}
+
+declare void @a(i8*) #1
+
+; CHECK-LABEL: @test2
+; CHECK-NOT: .asci
+; CHECK: .fnend
+define void @test2() #0 {
+ tail call void @a(i8* getelementptr inbounds ([69 x i8], [69 x i8]* @.str1, i32 0, i32 0)) #2
+ ret void
+}
+
+; CHECK-LABEL: @test3
+; CHECK: adr r0, [[x:.*]]
+; CHECK: [[x]]:
+; CHECK: .asciz "this string is just right!\000"
+define void @test3() #0 {
+ tail call void @a(i8* getelementptr inbounds ([27 x i8], [27 x i8]* @.str2, i32 0, i32 0)) #2
+ ret void
+}
+
+
+; CHECK-LABEL: @test4
+; CHECK: adr r{{.*}}, [[x:.*]]
+; CHECK: [[x]]:
+; CHECK: .asciz "this string is used twice\000\000"
+define void @test4() #0 {
+ tail call void @a(i8* getelementptr inbounds ([26 x i8], [26 x i8]* @.str3, i32 0, i32 0)) #2
+ tail call void @a(i8* getelementptr inbounds ([26 x i8], [26 x i8]* @.str3, i32 0, i32 0)) #2
+ ret void
+}
+
+; CHECK-LABEL: @test5a
+; CHECK-NOT: adr
+define void @test5a() #0 {
+ tail call void @a(i8* getelementptr inbounds ([29 x i8], [29 x i8]* @.str4, i32 0, i32 0)) #2
+ ret void
+}
+
+define void @test5b() #0 {
+ tail call void @b(i8* getelementptr inbounds ([29 x i8], [29 x i8]* @.str4, i32 0, i32 0)) #2
+ ret void
+}
+
+; CHECK-LABEL: @test6a
+; CHECK: adr r0, [[x:.*]]
+; CHECK: [[x]]:
+; CHECK: .short 3
+; CHECK: .short 4
+define void @test6a() #0 {
+ tail call void @c(i16* getelementptr inbounds ([2 x i16], [2 x i16]* @.arr1, i32 0, i32 0)) #2
+ ret void
+}
+
+; CHECK-LABEL: @test6b
+; CHECK: adr r0, [[x:.*]]
+; CHECK: [[x]]:
+; CHECK: .short 3
+; CHECK: .short 4
+define void @test6b() #0 {
+ tail call void @c(i16* getelementptr inbounds ([2 x i16], [2 x i16]* @.arr1, i32 0, i32 0)) #2
+ ret void
+}
+
+; This shouldn't be promoted, as the string is used by another global.
+; CHECK-LABEL: @test7
+; CHECK-NOT: adr
+define void @test7() #0 {
+ tail call void @c(i16* getelementptr inbounds ([2 x i16], [2 x i16]* @.arr2, i32 0, i32 0)) #2
+ ret void
+}
+
+declare void @b(i8*) #1
+declare void @c(i16*) #1
+
+attributes #0 = { nounwind "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #2 = { nounwind }
+
+!llvm.module.flags = !{!0, !1}
+!llvm.ident = !{!2}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 1, !"min_enum_size", i32 4}
+!2 = !{!"Apple LLVM version 6.1.0 (clang-602.0.53) (based on LLVM 3.6.0svn)"}
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