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ARM: properly lower dllimport'ed global values

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This completes the handling for DLL import storage symbols when lowering
instructions.  A DLL import storage symbol must have an additional load
performed prior to use.  This is applicable to variables and functions.

This is particularly important for non-function symbols as it is possible to
handle function references by emitting a thunk which performs the translation
from the unprefixed __imp_ symbol to the proper symbol (although, this is a
non-optimal lowering).  For a variable symbol, no such thunk can be
accommodated.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212431 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Saleem Abdulrasool 2014-07-07 05:18:35 +00:00
parent ecacffa147
commit 682e019983
2 changed files with 84 additions and 2 deletions
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25
lib/Target/ARM/ARMISelLowering.cpp
View File

@ -1654,6 +1654,19 @@ ARMTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
assert(Subtarget->isTargetMachO() && "WrapperPIC use on non-MachO?");
Callee = DAG.getNode(ARMISD::WrapperPIC, dl, getPointerTy(),
DAG.getTargetGlobalAddress(GV, dl, getPointerTy()));
} else if (Subtarget->isTargetCOFF()) {
assert(Subtarget->isTargetWindows() &&
"Windows is the only supported COFF target");
unsigned TargetFlags = GV->hasDLLImportStorageClass()
? ARMII::MO_DLLIMPORT
: ARMII::MO_NO_FLAG;
Callee = DAG.getTargetGlobalAddress(GV, dl, getPointerTy(), /*Offset=*/0,
TargetFlags);
if (GV->hasDLLImportStorageClass())
Callee = DAG.getLoad(getPointerTy(), dl, DAG.getEntryNode(),
DAG.getNode(ARMISD::Wrapper, dl, getPointerTy(),
Callee), MachinePointerInfo::getGOT(),
false, false, false, 0);
} else {
// On ELF targets for PIC code, direct calls should go through the PLT
unsigned OpFlags = 0;
@ -2489,15 +2502,23 @@ SDValue ARMTargetLowering::LowerGlobalAddressWindows(SDValue Op,
"Windows on ARM expects to use movw/movt");
const GlobalValue *GV = cast<GlobalAddressSDNode>(Op)->getGlobal();
const ARMII::TOF TargetFlags =
(GV->hasDLLImportStorageClass() ? ARMII::MO_DLLIMPORT : ARMII::MO_NO_FLAG);
EVT PtrVT = getPointerTy();
SDValue Result;
SDLoc DL(Op);
++NumMovwMovt;
// FIXME: Once remat is capable of dealing with instructions with register
// operands, expand this into two nodes.
return DAG.getNode(ARMISD::Wrapper, DL, PtrVT,
DAG.getTargetGlobalAddress(GV, DL, PtrVT));
Result = DAG.getNode(ARMISD::Wrapper, DL, PtrVT,
DAG.getTargetGlobalAddress(GV, DL, PtrVT, /*Offset=*/0,
TargetFlags));
if (GV->hasDLLImportStorageClass())
Result = DAG.getLoad(PtrVT, DL, DAG.getEntryNode(), Result,
MachinePointerInfo::getGOT(), false, false, false, 0);
return Result;
}
SDValue ARMTargetLowering::LowerGLOBAL_OFFSET_TABLE(SDValue Op,

61
test/CodeGen/ARM/Windows/dllimport.ll Normal file
View File

@ -0,0 +1,61 @@
; RUN: llc -mtriple thumbv7-windows -filetype asm -o - %s | FileCheck %s
; ModuleID = 'dllimport.c'
@var = external dllimport global i32
@ext = external global i32
declare dllimport arm_aapcs_vfpcc i32 @external()
declare arm_aapcs_vfpcc i32 @internal()
define arm_aapcs_vfpcc i32 @get_var() {
%1 = load i32* @var, align 4
ret i32 %1
}
; CHECK-LABEL: get_var
; CHECK: movw r0, :lower16:__imp_var
; CHECK: movt r0, :upper16:__imp_var
; CHECK: ldr r0, [r0]
; CHECK: ldr r0, [r0]
; CHECK: bx lr
define arm_aapcs_vfpcc i32 @get_ext() {
%1 = load i32* @ext, align 4
ret i32 %1
}
; CHECK-LABEL: get_ext
; CHECK: movw r0, :lower16:ext
; CHECK: movt r0, :upper16:ext
; CHECK: ldr r0, [r0]
; CHECK: bx lr
define arm_aapcs_vfpcc i32* @get_var_pointer() {
ret i32* @var
}
; CHECK-LABEL: get_var_pointer
; CHECK: movw r0, :lower16:__imp_var
; CHECK: movt r0, :upper16:__imp_var
; CHECK: ldr r0, [r0]
; CHECK: bx lr
define arm_aapcs_vfpcc i32 @call_external() {
%call = tail call arm_aapcs_vfpcc i32 @external()
ret i32 %call
}
; CHECK-LABEL: call_external
; CHECK: movw r0, :lower16:__imp_external
; CHECK: movt r0, :upper16:__imp_external
; CHECK: ldr r0, [r0]
; CHECK: bx r0
define arm_aapcs_vfpcc i32 @call_internal() {
%call = tail call arm_aapcs_vfpcc i32 @internal()
ret i32 %call
}
; CHECK-LABEL: call_internal
; CHECK: b internal