bugfix: When the source register of CALL_NOLINK was LR, the following code was emitted:

    mov lr, pc
    bx lr
So, the function was not called.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35218 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 81 insertions, 19 deletions

diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index afaea04..bd7fa5c 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -544,6 +544,24 @@ SDOperand ARMTargetLowering::LowerCALL(SDOperand Op, SelectionDAG &DAG) {
       Callee = DAG.getTargetExternalSymbol(Sym, getPointerTy());
   }
 
+  // FIXME: handle tail calls differently.
+  unsigned CallOpc;
+  if (Subtarget->isThumb()) {
+    if (!Subtarget->hasV5TOps() && (!isDirect || isARMFunc))
+      CallOpc = ARMISD::CALL_NOLINK;
+    else
+      CallOpc = isARMFunc ? ARMISD::CALL : ARMISD::tCALL;
+  } else {
+    CallOpc = (isDirect || Subtarget->hasV5TOps())
+      ? ARMISD::CALL : ARMISD::CALL_NOLINK;
+  }
+  if (CallOpc == ARMISD::CALL_NOLINK) {
+    // On CALL_NOLINK we must move PC to LR
+    Chain = DAG.getCopyToReg(Chain, ARM::LR,
+                             DAG.getRegister(ARM::PC, MVT::i32), InFlag);
+    InFlag = Chain.getValue(1);
+  }
+
   std::vector<MVT::ValueType> NodeTys;
   NodeTys.push_back(MVT::Other);   // Returns a chain
   NodeTys.push_back(MVT::Flag);    // Returns a flag for retval copy to use.
@@ -558,17 +576,6 @@ SDOperand ARMTargetLowering::LowerCALL(SDOperand Op, SelectionDAG &DAG) {
     Ops.push_back(DAG.getRegister(RegsToPass[i].first,
                                   RegsToPass[i].second.getValueType()));
 
-  // FIXME: handle tail calls differently.
-  unsigned CallOpc;
-  if (Subtarget->isThumb()) {
-    if (!Subtarget->hasV5TOps() && (!isDirect || isARMFunc))
-      CallOpc = ARMISD::CALL_NOLINK;
-    else
-      CallOpc = isARMFunc ? ARMISD::CALL : ARMISD::tCALL;
-  } else {
-    CallOpc = (isDirect || Subtarget->hasV5TOps())
-      ? ARMISD::CALL : ARMISD::CALL_NOLINK;
-  }
   if (InFlag.Val)
     Ops.push_back(InFlag);
   Chain = DAG.getNode(CallOpc, NodeTys, &Ops[0], Ops.size());
diff --git a/lib/Target/ARM/ARMInstrInfo.td b/lib/Target/ARM/ARMInstrInfo.td
index bb8b61f..201f65c 100644
--- a/lib/Target/ARM/ARMInstrInfo.td
+++ b/lib/Target/ARM/ARMInstrInfo.td
@@ -370,8 +370,6 @@ class AI3<dag ops, string asm, list<dag> pattern>
   : I<ops, AddrMode3, Size4Bytes, IndexModeNone, asm, "", pattern>;
 class AI4<dag ops, string asm, list<dag> pattern>
   : I<ops, AddrMode4, Size4Bytes, IndexModeNone, asm, "", pattern>;
-class AIx2<dag ops, string asm, list<dag> pattern>
-  : I<ops, AddrModeNone, Size8Bytes, IndexModeNone, asm, "", pattern>;
 class AI1x2<dag ops, string asm, list<dag> pattern>
   : I<ops, AddrMode1, Size8Bytes, IndexModeNone, asm, "", pattern>;
 
@@ -546,10 +544,12 @@ let isCall = 1, noResults = 1,
   def BLX : AI<(ops GPR:$dst, variable_ops),
                "blx $dst",
                [(ARMcall GPR:$dst)]>, Requires<[IsARM, HasV5T]>;
-  // ARMv4T
-  def BX : AIx2<(ops GPR:$dst, variable_ops),
-                "mov lr, pc\n\tbx $dst",
+  let Uses = [LR] in {
+    // ARMv4T
+    def BX : AI<(ops GPR:$dst, variable_ops),
+                "bx $dst",
                 [(ARMcall_nolink GPR:$dst)]>;
+  }
 }
 
 let isBranch = 1, isTerminator = 1, isBarrier = 1 in {
diff --git a/lib/Target/ARM/ARMInstrThumb.td b/lib/Target/ARM/ARMInstrThumb.td
index 3c7cd03..a1f03bd 100644
--- a/lib/Target/ARM/ARMInstrThumb.td
+++ b/lib/Target/ARM/ARMInstrThumb.td
@@ -189,10 +189,12 @@ let isCall = 1, noResults = 1,
   def tBLXr : TI<(ops GPR:$dst, variable_ops),
                   "blx $dst",
                   [(ARMtcall GPR:$dst)]>, Requires<[HasV5T]>;
-  // ARMv4T
-  def tBX : TIx2<(ops GPR:$dst, variable_ops),
-                  "cpy lr, pc\n\tbx $dst",
+  let Uses = [LR] in {
+    // ARMv4T
+    def tBX : TI<(ops GPR:$dst, variable_ops),
+                  "bx $dst",
                   [(ARMcall_nolink GPR:$dst)]>;
+  }
 }
 
 let isBranch = 1, isTerminator = 1, isBarrier = 1 in {
diff --git a/test/CodeGen/ARM/call_nolink.ll b/test/CodeGen/ARM/call_nolink.ll
new file mode 100644
index 0000000..fa1641d
--- /dev/null
+++ b/test/CodeGen/ARM/call_nolink.ll
@@ -0,0 +1,53 @@
+; RUN: llvm-as < %s | llc -march=arm &&
+; RUN: llvm-as < %s | llc -march=arm -mtriple=arm-linux-gnueabi | not grep "bx lr"
+
+	%struct.anon = type { i32 (i32, i32, i32)*, i32, i32, [3 x i32], i8*, i8*, i8* }
+@r = external global [14 x i32]		; <[14 x i32]*> [#uses=4]
+@isa = external global [13 x %struct.anon]		; <[13 x %struct.anon]*> [#uses=1]
+@pgm = external global [2 x { i32, [3 x i32] }]		; <[2 x { i32, [3 x i32] }]*> [#uses=4]
+@numi = external global i32		; <i32*> [#uses=1]
+@counter = external global [2 x i32]		; <[2 x i32]*> [#uses=1]
+
+implementation   ; Functions:
+
+define void @main_bb_2E_i_bb205_2E_i_2E_i_bb115_2E_i_2E_i() {
+newFuncRoot:
+	br label %bb115.i.i
+
+bb115.i.i.bb170.i.i_crit_edge.exitStub:		; preds = %bb115.i.i
+	ret void
+
+bb115.i.i.bb115.i.i_crit_edge:		; preds = %bb115.i.i
+	br label %bb115.i.i
+
+bb115.i.i:		; preds = %bb115.i.i.bb115.i.i_crit_edge, %newFuncRoot
+	%i_addr.3210.0.i.i = phi i32 [ %tmp166.i.i, %bb115.i.i.bb115.i.i_crit_edge ], [ 0, %newFuncRoot ]		; <i32> [#uses=7]
+	%tmp124.i.i = getelementptr [2 x { i32, [3 x i32] }]* @pgm, i32 0, i32 %i_addr.3210.0.i.i, i32 1, i32 0		; <i32*> [#uses=1]
+	%tmp125.i.i = load i32* %tmp124.i.i		; <i32> [#uses=1]
+	%tmp126.i.i = getelementptr [14 x i32]* @r, i32 0, i32 %tmp125.i.i		; <i32*> [#uses=1]
+	%tmp127.i.i = load i32* %tmp126.i.i		; <i32> [#uses=1]
+	%tmp131.i.i = getelementptr [2 x { i32, [3 x i32] }]* @pgm, i32 0, i32 %i_addr.3210.0.i.i, i32 1, i32 1		; <i32*> [#uses=1]
+	%tmp132.i.i = load i32* %tmp131.i.i		; <i32> [#uses=1]
+	%tmp133.i.i = getelementptr [14 x i32]* @r, i32 0, i32 %tmp132.i.i		; <i32*> [#uses=1]
+	%tmp134.i.i = load i32* %tmp133.i.i		; <i32> [#uses=1]
+	%tmp138.i.i = getelementptr [2 x { i32, [3 x i32] }]* @pgm, i32 0, i32 %i_addr.3210.0.i.i, i32 1, i32 2		; <i32*> [#uses=1]
+	%tmp139.i.i = load i32* %tmp138.i.i		; <i32> [#uses=1]
+	%tmp140.i.i = getelementptr [14 x i32]* @r, i32 0, i32 %tmp139.i.i		; <i32*> [#uses=1]
+	%tmp141.i.i = load i32* %tmp140.i.i		; <i32> [#uses=1]
+	%tmp143.i.i = add i32 %i_addr.3210.0.i.i, 12		; <i32> [#uses=1]
+	%tmp146.i.i = getelementptr [2 x { i32, [3 x i32] }]* @pgm, i32 0, i32 %i_addr.3210.0.i.i, i32 0		; <i32*> [#uses=1]
+	%tmp147.i.i = load i32* %tmp146.i.i		; <i32> [#uses=1]
+	%tmp149.i.i = getelementptr [13 x %struct.anon]* @isa, i32 0, i32 %tmp147.i.i, i32 0		; <i32 (i32, i32, i32)**> [#uses=1]
+	%tmp150.i.i = load i32 (i32, i32, i32)** %tmp149.i.i		; <i32 (i32, i32, i32)*> [#uses=1]
+	%tmp154.i.i = tail call i32 %tmp150.i.i( i32 %tmp127.i.i, i32 %tmp134.i.i, i32 %tmp141.i.i )		; <i32> [#uses=1]
+	%tmp155.i.i = getelementptr [14 x i32]* @r, i32 0, i32 %tmp143.i.i		; <i32*> [#uses=1]
+	store i32 %tmp154.i.i, i32* %tmp155.i.i
+	%tmp159.i.i = getelementptr [2 x i32]* @counter, i32 0, i32 %i_addr.3210.0.i.i		; <i32*> [#uses=2]
+	%tmp160.i.i = load i32* %tmp159.i.i		; <i32> [#uses=1]
+	%tmp161.i.i = add i32 %tmp160.i.i, 1		; <i32> [#uses=1]
+	store i32 %tmp161.i.i, i32* %tmp159.i.i
+	%tmp166.i.i = add i32 %i_addr.3210.0.i.i, 1		; <i32> [#uses=2]
+	%tmp168.i.i = load i32* @numi		; <i32> [#uses=1]
+	icmp slt i32 %tmp166.i.i, %tmp168.i.i		; <i1>:0 [#uses=1]
+	br i1 %0, label %bb115.i.i.bb115.i.i_crit_edge, label %bb115.i.i.bb170.i.i_crit_edge.exitStub
+}