// Emit the rest of the function body.
EmitFunctionBody();
+ // If we need V4T thumb mode Register Indirect Jump pads, emit them.
+ // These are created per function, rather than per TU, since it's
+ // relatively easy to exceed the thumb branch range within a TU.
+ if (! ThumbIndirectPads.empty()) {
+ OutStreamer.EmitAssemblerFlag(MCAF_Code16);
+ EmitAlignment(1);
+ for (unsigned i = 0, e = ThumbIndirectPads.size(); i < e; i++) {
+ OutStreamer.EmitLabel(ThumbIndirectPads[i].second);
+ EmitToStreamer(OutStreamer, MCInstBuilder(ARM::tBX)
+ .addReg(ThumbIndirectPads[i].first)
+ // Add predicate operands.
+ .addImm(ARMCC::AL)
+ .addReg(0));
+ }
+ ThumbIndirectPads.clear();
+ }
+
// We didn't modify anything.
return false;
}
return;
}
case ARM::tBX_CALL: {
- EmitToStreamer(OutStreamer, MCInstBuilder(ARM::tMOVr)
- .addReg(ARM::LR)
- .addReg(ARM::PC)
- // Add predicate operands.
- .addImm(ARMCC::AL)
- .addReg(0));
+ if (Subtarget->hasV5TOps())
+ llvm_unreachable("Expected BLX to be selected for v5t+");
+
+ // On ARM v4t, when doing a call from thumb mode, we need to ensure
+ // that the saved lr has its LSB set correctly (the arch doesn't
+ // have blx).
+ // So here we generate a bl to a small jump pad that does bx rN.
+ // The jump pads are emitted after the function body.
+
+ unsigned TReg = MI->getOperand(0).getReg();
+ MCSymbol *TRegSym = nullptr;
+ for (unsigned i = 0, e = ThumbIndirectPads.size(); i < e; i++) {
+ if (ThumbIndirectPads[i].first == TReg) {
+ TRegSym = ThumbIndirectPads[i].second;
+ break;
+ }
+ }
- EmitToStreamer(OutStreamer, MCInstBuilder(ARM::tBX)
- .addReg(MI->getOperand(0).getReg())
- // Add predicate operands.
- .addImm(ARMCC::AL)
- .addReg(0));
+ if (!TRegSym) {
+ TRegSym = OutContext.CreateTempSymbol();
+ ThumbIndirectPads.push_back(std::make_pair(TReg, TRegSym));
+ }
+
+ // Create a link-saving branch to the Reg Indirect Jump Pad.
+ EmitToStreamer(OutStreamer, MCInstBuilder(ARM::tBL)
+ // Predicate comes first here.
+ .addImm(ARMCC::AL).addReg(0)
+ .addExpr(MCSymbolRefExpr::Create(TRegSym, OutContext)));
return;
}
case ARM::BMOVPCRX_CALL: {
class MCOperand;
class MachineConstantPool;
class MachineOperand;
+class MCSymbol;
namespace ARM {
enum DW_ISA {
/// InConstantPool - Maintain state when emitting a sequence of constant
/// pool entries so we can properly mark them as data regions.
bool InConstantPool;
+
+ /// ThumbIndirectPads - These maintain a per-function list of jump pad
+ /// labels used for ARMv4t thumb code to make register indirect calls.
+ SmallVector<std::pair<unsigned, MCSymbol*>, 4> ThumbIndirectPads;
+
public:
explicit ARMAsmPrinter(TargetMachine &TM, MCStreamer &Streamer)
: AsmPrinter(TM, Streamer), AFI(nullptr), MCP(nullptr),
--- /dev/null
+; RUN: llc -mtriple=thumbv4t-eabi %s -o - | FileCheck ---check-prefix=CHECK -check-prefix=CHECK-V4T %s
+; RUN: llc -mtriple=thumbv5t-eabi %s -o - | FileCheck ---check-prefix=CHECK -check-prefix=CHECK-V5T %s
+
+@f = common global void (i32)* null, align 4
+
+; CHECK-LABEL foo:
+define void @foo(i32 %x) {
+entry:
+ %0 = load void (i32)** @f, align 4
+ tail call void %0(i32 %x)
+ ret void
+
+; CHECK: ldr [[TMP:r[0-3]]], [[F:\.[A-Z0-9_]+]]
+; CHECK: ldr [[CALLEE:r[0-3]]], {{\[}}[[TMP]]{{\]}}
+
+; CHECK-V4T-NOT: blx
+; CHECK-V4T: bl [[INDIRECT_PAD:\.Ltmp[0-9]+]]
+; CHECK-V4T: [[F]]:
+; CHECK-V4T: [[INDIRECT_PAD]]:
+; CHECK-V4T-NEXT: bx [[CALLEE]]
+; CHECK-V5T: blx [[CALLEE]]
+}
+
+; CHECK-LABEL bar:
+define void @bar(void (i32)* nocapture %g, i32 %x, void (i32)* nocapture %h) {
+entry:
+ tail call void %g(i32 %x)
+ tail call void %h(i32 %x)
+ ret void
+
+; CHECK-V4T: bl [[INDIRECT_PAD1:\.Ltmp[0-9]+]]
+; CHECK-V4T: bl [[INDIRECT_PAD2:\.Ltmp[0-9]+]]
+; CHECK-V4T: [[INDIRECT_PAD1]]:
+; CHECK-V4T-NEXT: bx
+; CHECK-V4T: [[INDIRECT_PAD2]]:
+; CHECK-V4T-NEXT: bx
+; CHECK-V5T: blx
+; CHECK-V5T: blx
+}
+