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[ARM] [Windows] Use COFF stubs for calls to extern_weak functions

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As the extern_weak target might be missing, resolving to the absolute
address zero, we can't use the normal direct PC-relative branch
instructions (as that would result in relocations out of range).

Instead check the shouldAssumeDSOLocal method and load the address
from a COFF stub.

This matches what was done for X86 in 6bf108d77a3c.

Differential Revision: https://reviews.llvm.org/D71720
This commit is contained in:
Martin Storsjö 2019-12-19 14:00:44 +02:00
parent 8452e4df8a
commit 407a0e7a75
2 changed files with 12 additions and 7 deletions
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10
lib/Target/ARM/ARMISelLowering.cpp
View File

@ -2356,12 +2356,14 @@ ARMTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
} 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;
unsigned TargetFlags = ARMII::MO_NO_FLAG;
if (GV->hasDLLImportStorageClass())
TargetFlags = ARMII::MO_DLLIMPORT;
else if (!TM.shouldAssumeDSOLocal(*GV->getParent(), GV))
TargetFlags = ARMII::MO_COFFSTUB;
Callee = DAG.getTargetGlobalAddress(GV, dl, PtrVt, /*offset=*/0,
TargetFlags);
if (GV->hasDLLImportStorageClass())
if (TargetFlags & (ARMII::MO_DLLIMPORT | ARMII::MO_COFFSTUB))
Callee =
DAG.getLoad(PtrVt, dl, DAG.getEntryNode(),
DAG.getNode(ARMISD::Wrapper, dl, PtrVt, Callee),

9
test/CodeGen/ARM/tail-call-weak.ll
View File

@ -5,14 +5,17 @@
declare i8* @f()
declare extern_weak i8* @g(i8*)
; weak symbol resolution occurs statically in PE/COFF, ensure that we permit
; tail calls on weak externals when targeting a COFF environment.
define void @test() {
%call = tail call i8* @f()
%call1 = tail call i8* @g(i8* %call)
ret void
}
; CHECK-COFF: b g
; CHECK-COFF: movw r0, :lower16:.refptr.g
; CHECK-COFF: movt r0, :upper16:.refptr.g
; CHECK-COFF: ldr r4, [r0]
; CHECK-COFF: mov r1, r4
; CHECK-COFF: bx r1
; CHECK-OTHER: bl {{_?}}g