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[ARM] support -mlong-calls -fPIC on arm32 #39970 #147313

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[ARM] support -mlong-calls -fPIC on arm32 #39970 #147313

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14 changes: 12 additions & 2 deletions llvm/lib/Target/ARM/ARMISelLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2793,8 +2793,6 @@ ARMTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
auto PtrVt = getPointerTy(DAG.getDataLayout());

if (Subtarget->genLongCalls()) {
assert((!isPositionIndependent() || Subtarget->isTargetWindows()) &&
"long-calls codegen is not position independent!");
// Handle a global address or an external symbol. If it's not one of
// those, the target's already in a register, so we don't need to do
// anything extra.
Expand All @@ -2804,6 +2802,14 @@ ARMTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
++NumMovwMovt;
Callee = DAG.getNode(ARMISD::Wrapper, dl, PtrVt,
DAG.getTargetGlobalAddress(GVal, dl, PtrVt));
} else if (isPositionIndependent() && !Subtarget->isTargetWindows()){
SDValue G = DAG.getTargetGlobalAddress(
GVal, dl, PtrVt, 0, GVal->isDSOLocal() ? 0 : ARMII::MO_GOT);
Callee = DAG.getNode(ARMISD::WrapperPIC, dl, PtrVt, G);
if (!GVal->isDSOLocal())
Callee =
DAG.getLoad(PtrVt, dl, DAG.getEntryNode(), Callee,
MachinePointerInfo::getGOT(DAG.getMachineFunction()));
} else {
// Create a constant pool entry for the callee address
unsigned ARMPCLabelIndex = AFI->createPICLabelUId();
Expand Down Expand Up @@ -2837,6 +2843,10 @@ ARMTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
Callee = DAG.getLoad(
PtrVt, dl, DAG.getEntryNode(), Addr,
MachinePointerInfo::getConstantPool(DAG.getMachineFunction()));
if (isPositionIndependent() && !Subtarget->isTargetWindows()) {
SDValue PICLabel = DAG.getConstant(ARMPCLabelIndex, dl, MVT::i32);
Callee = DAG.getNode(ARMISD::PIC_ADD, dl, PtrVt, Callee, PICLabel);
}
}
}
} else if (isa<GlobalAddressSDNode>(Callee)) {
Expand Down
61 changes: 61 additions & 0 deletions llvm/test/CodeGen/ARM/subtarget-features-long-calls.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,9 @@
; RUN: llc -mtriple=thumb-- -mcpu=cortex-a8 -relocation-model=static %s -o - -O0 | FileCheck -check-prefix=NO-OPTION %s
; RUN: llc -mtriple=thumb-- -mcpu=cortex-a8 -relocation-model=static %s -o - -O0 -mattr=+long-calls | FileCheck -check-prefix=LONGCALL %s
; RUN: llc -mtriple=thumb-- -mcpu=cortex-a8 -relocation-model=static %s -o - -O0 -mattr=-long-calls | FileCheck -check-prefix=NO-LONGCALL %s
; RUN: llc -mtriple=arm-linux-gnueabi -mcpu=cortex-a8 -relocation-model=pic %s -o - -O0 -mattr=+long-calls | FileCheck -check-prefix=PIC-O0-LONGCALL %s
; RUN: llc -mtriple=arm-linux-gnueabi -mcpu=cortex-a8 -relocation-model=pic %s -o - -O1 -mattr=+long-calls | FileCheck -check-prefix=PIC-LONGCALL %s
; RUN: llc -mtriple=arm-linux-gnueabi -mcpu=cortex-a8 -relocation-model=pic %s -o - -O2 -mattr=+long-calls | FileCheck -check-prefix=PIC-LONGCALL %s
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You don't need both -O1 and -O2; -O0 is special in this context because it triggers globalisel/fastisel.

Please add RUN lines for execute-only, so we can see they work.

Please regenerate the CHECK lines with update_llc_test_checks.py, so it's easier to read/update.


; NO-OPTION-LABEL: {{_?}}caller0
; NO-OPTION: ldr [[R0:r[0-9]+]], [[L0:.*]]
Expand Down Expand Up @@ -46,4 +49,62 @@ entry:

declare void @callee0()

; PIC-O0-LONGCALL-LABEL: global_func:
; PIC-O0-LONGCALL: bx lr

; PIC-LONGCALL-LABEL: global_func:
; PIC-LONGCALL: bx lr
define void @global_func() {
entry:
ret void
}

; PIC-O0-LONGCALL-LABEL: test_global:
; PIC-O0-LONGCALL: push {r11, lr}
; PIC-O0-LONGCALL: ldr r0, [[GOT_LABEL:.*]]
; PIC-O0-LONGCALL: ldr r0, [pc, r0]
; PIC-O0-LONGCALL: blx r0
; PIC-O0-LONGCALL: pop {r11, pc}
; PIC-O0-LONGCALL: [[GOT_LABEL]]:
; PIC-O0-LONGCALL: .long global_func(GOT_PREL)

; PIC-LONGCALL-LABEL: test_global:
; PIC-LONGCALL: push {r11, lr}
; PIC-LONGCALL: ldr r0, [[GOT_LABEL:.*]]
; PIC-LONGCALL: ldr r0, [pc, r0]
; PIC-LONGCALL: blx r0
; PIC-LONGCALL: pop {r11, pc}
; PIC-LONGCALL: [[GOT_LABEL]]:
; PIC-LONGCALL: .long global_func(GOT_PREL)
define void @test_global() {
entry:
call void @global_func()
ret void
}

; PIC-O0-LONGCALL-LABEL: test_memset:
; PIC-O0-LONGCALL: push {r11, lr}
; PIC-O0-LONGCALL: ldr r3, [[GOT_LABEL:.*]]
; PIC-O0-LONGCALL: ldr r3, [pc, r3]
; PIC-O0-LONGCALL: blx r3
; PIC-O0-LONGCALL: pop {r11, pc}
; PIC-O0-LONGCALL: [[GOT_LABEL]]:
; PIC-O0-LONGCALL: .long memset(GOT_PREL)

; PIC-LONGCALL-LABEL: test_memset:
; PIC-LONGCALL: push {r11, lr}
; PIC-LONGCALL: ldr r3, [[MEMSET_LABEL:.*]]
; PIC-LONGCALL: add r3, pc, r3
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The -O1 code is wrong. The -O0 code is also wrong.

Look at what we do for something like extern int x; int* f() { return &x; }. Or look at what we do for __attribute((visibility("hidden"))) extern int x; int* f() { return &x; }.

; PIC-LONGCALL: blx r3
; PIC-LONGCALL: pop {r11, pc}
; PIC-LONGCALL: [[MEMSET_LABEL]]:
; PIC-LONGCALL: .long memset
declare void @llvm.memset.p0.i32(ptr nocapture writeonly, i8, i32, i1 immarg)

define void @test_memset(ptr %dst, i8 %val, i32 %len) {
entry:
call void @llvm.memset.p0.i32(ptr %dst, i8 %val, i32 %len, i1 false)
ret void
}

attributes #0 = { "target-features"="+long-calls" }
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