Index: llvm/trunk/lib/Target/ARM/ARMFrameLowering.cpp
===================================================================
--- llvm/trunk/lib/Target/ARM/ARMFrameLowering.cpp
+++ llvm/trunk/lib/Target/ARM/ARMFrameLowering.cpp
@@ -1920,9 +1920,13 @@
                         << "\n");
     }
 
+    // Avoid spilling LR in Thumb1 if there's a tail call: it's expensive to
+    // restore LR in that case.
+    bool ExpensiveLRRestore = AFI->isThumb1OnlyFunction() && MFI.hasTailCall();
+
     // If LR is not spilled, but at least one of R4, R5, R6, and R7 is spilled.
     // Spill LR as well so we can fold BX_RET to the registers restore (LDM).
-    if (!LRSpilled && CS1Spilled) {
+    if (!LRSpilled && CS1Spilled && !ExpensiveLRRestore) {
       SavedRegs.set(ARM::LR);
       NumGPRSpills++;
       SmallVectorImpl<unsigned>::iterator LRPos;
@@ -1948,7 +1952,8 @@
           // Windows on ARM, accept R11 (frame pointer)
           if (!AFI->isThumbFunction() ||
               (STI.isTargetWindows() && Reg == ARM::R11) ||
-              isARMLowRegister(Reg) || Reg == ARM::LR) {
+              isARMLowRegister(Reg) ||
+              (Reg == ARM::LR && !ExpensiveLRRestore)) {
             SavedRegs.set(Reg);
             LLVM_DEBUG(dbgs() << "Spilling " << printReg(Reg, TRI)
                               << " to make up alignment\n");
Index: llvm/trunk/test/CodeGen/ARM/v8m-tail-call.ll
===================================================================
--- llvm/trunk/test/CodeGen/ARM/v8m-tail-call.ll
+++ llvm/trunk/test/CodeGen/ARM/v8m-tail-call.ll
@@ -1,34 +1,65 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc %s -o - -mtriple=thumbv8m.base | FileCheck %s
 
 declare i32 @g(...)
 
 declare i32 @h0(i32, i32, i32, i32)
 define hidden i32 @f0() {
+; CHECK-LABEL: f0:
+; CHECK:       @ %bb.0:
+; CHECK-NEXT:    push {r7, lr}
+; CHECK-NEXT:    bl g
+; CHECK-NEXT:    movs r1, #1
+; CHECK-NEXT:    movs r2, #2
+; CHECK-NEXT:    movs r3, #3
+; CHECK-NEXT:    ldr r7, [sp, #4]
+; CHECK-NEXT:    mov lr, r7
+; CHECK-NEXT:    pop {r7}
+; CHECK-NEXT:    add sp, #4
+; CHECK-NEXT:    b h0
   %1 = tail call i32 bitcast (i32 (...)* @g to i32 ()*)()
   %2 = tail call i32 @h0(i32 %1, i32 1, i32 2, i32 3)
   ret i32 %2
-; CHECK-LABEL: f0
-; CHECK:      ldr     [[POP:r[4567]]], [sp, #4]
-; CHECK-NEXT: mov     lr, [[POP]]
-; CHECK-NEXT: pop     {{.*}}[[POP]]
-; CHECK-NEXT: add     sp, #4
-; CHECK-NEXT: b       h0
 }
 
 declare i32 @h1(i32)
 define hidden i32 @f1() {
+; CHECK-LABEL: f1:
+; CHECK:       @ %bb.0:
+; CHECK-NEXT:    push {r7, lr}
+; CHECK-NEXT:    bl g
+; CHECK-NEXT:    pop {r7}
+; CHECK-NEXT:    pop {r1}
+; CHECK-NEXT:    mov lr, r1
+; CHECK-NEXT:    b h1
   %1 = tail call i32 bitcast (i32 (...)* @g to i32 ()*)()
   %2 = tail call i32 @h1(i32 %1)
   ret i32 %2
-; CHECK-LABEL: f1
-; CHECK: pop     {r7}
-; CHECK: pop     {r1}
-; CHECK: mov     lr, r1
-; CHECK: b       h1
 }
 
 declare i32 @h2(i32, i32, i32, i32, i32)
 define hidden i32 @f2(i32, i32, i32, i32, i32) {
+; CHECK-LABEL: f2:
+; CHECK:       @ %bb.0:
+; CHECK-NEXT:    push {r4, r5, r6, lr}
+; CHECK-NEXT:    mov r4, r3
+; CHECK-NEXT:    mov r5, r2
+; CHECK-NEXT:    mov r6, r1
+; CHECK-NEXT:    bl g
+; CHECK-NEXT:    cbz r0, .LBB2_2
+; CHECK-NEXT:  @ %bb.1:
+; CHECK-NEXT:    mov r1, r6
+; CHECK-NEXT:    mov r2, r5
+; CHECK-NEXT:    mov r3, r4
+; CHECK-NEXT:    ldr r4, [sp, #12]
+; CHECK-NEXT:    mov lr, r4
+; CHECK-NEXT:    pop {r4, r5, r6}
+; CHECK-NEXT:    add sp, #4
+; CHECK-NEXT:    b h2
+; CHECK-NEXT:  .LBB2_2:
+; CHECK-NEXT:    movs r0, #0
+; CHECK-NEXT:    mvns r0, r0
+; CHECK-NEXT:    pop {r4, r5, r6, pc}
   %6 = tail call i32 bitcast (i32 (...)* @g to i32 ()*)()
   %7 = icmp eq i32 %6, 0
   br i1 %7, label %10, label %8
@@ -38,12 +69,6 @@
 
   %11 = phi i32 [ %9, %8 ], [ -1, %5 ]
   ret i32 %11
-; CHECK-LABEL: f2
-; CHECK:      ldr     [[POP:r[4567]]], [sp, #12]
-; CHECK-NEXT: mov     lr, [[POP]]
-; CHECK-NEXT: pop     {{.*}}[[POP]]
-; CHECK-NEXT: add     sp, #4
-; CHECK-NEXT: b       h2
 }
 
 ; Make sure that tail calls to function pointers that require r0-r3 for argument
@@ -51,7 +76,17 @@
 @fnptr = global i32 (i32, i32, i32, i32)* null
 define i32 @test3() {
 ; CHECK-LABEL: test3:
-; CHECK: blx {{r[0-9]+}}
+; CHECK:       @ %bb.0:
+; CHECK-NEXT:    push {r4, lr}
+; CHECK-NEXT:    movw r0, :lower16:fnptr
+; CHECK-NEXT:    movt r0, :upper16:fnptr
+; CHECK-NEXT:    ldr r4, [r0]
+; CHECK-NEXT:    movs r0, #1
+; CHECK-NEXT:    movs r1, #2
+; CHECK-NEXT:    movs r2, #3
+; CHECK-NEXT:    movs r3, #4
+; CHECK-NEXT:    blx r4
+; CHECK-NEXT:    pop {r4, pc}
   %1 = load i32 (i32, i32, i32, i32)*, i32 (i32, i32, i32, i32)** @fnptr
   %2 = tail call i32 %1(i32 1, i32 2, i32 3, i32 4)
   ret i32 %2
@@ -60,7 +95,17 @@
 @fnptr2 = global i32 (i32, i32, i64)* null
 define i32 @test4() {
 ; CHECK-LABEL: test4:
-; CHECK: blx {{r[0-9]+}}
+; CHECK:       @ %bb.0:
+; CHECK-NEXT:    push {r4, lr}
+; CHECK-NEXT:    movw r0, :lower16:fnptr2
+; CHECK-NEXT:    movt r0, :upper16:fnptr2
+; CHECK-NEXT:    ldr r4, [r0]
+; CHECK-NEXT:    movs r0, #1
+; CHECK-NEXT:    movs r1, #2
+; CHECK-NEXT:    movs r2, #3
+; CHECK-NEXT:    movs r3, #0
+; CHECK-NEXT:    blx r4
+; CHECK-NEXT:    pop {r4, pc}
   %1 = load i32 (i32, i32, i64)*, i32 (i32, i32, i64)** @fnptr2
   %2 = tail call i32 %1(i32 1, i32 2, i64 3)
   ret i32 %2
@@ -72,9 +117,13 @@
 @fnptr3 = global i32 (i32, i32)* null
 define i32 @test5() {
 ; CHECK-LABEL: test5:
-; CHECK: ldr [[REG:r[0-9]+]]
-; CHECK: bx [[REG]]
-; CHECK-NOT: blx [[REG]]
+; CHECK:       @ %bb.0:
+; CHECK-NEXT:    movw r0, :lower16:fnptr3
+; CHECK-NEXT:    movt r0, :upper16:fnptr3
+; CHECK-NEXT:    ldr r2, [r0]
+; CHECK-NEXT:    movs r0, #1
+; CHECK-NEXT:    movs r1, #2
+; CHECK-NEXT:    bx r2
   %1 = load i32 (i32, i32)*, i32 (i32, i32)** @fnptr3
   %2 = tail call i32 %1(i32 1, i32 2)
   ret i32 %2
@@ -84,9 +133,14 @@
 @fnptr4 = global i32 (i32, i64)* null
 define i32 @test6() {
 ; CHECK-LABEL: test6:
-; CHECK: ldr [[REG:r[0-9]+]]
-; CHECK: bx [[REG]]
-; CHECK-NOT: blx [[REG]]
+; CHECK:       @ %bb.0:
+; CHECK-NEXT:    movw r0, :lower16:fnptr4
+; CHECK-NEXT:    movt r0, :upper16:fnptr4
+; CHECK-NEXT:    ldr r1, [r0]
+; CHECK-NEXT:    movs r0, #1
+; CHECK-NEXT:    movs r2, #2
+; CHECK-NEXT:    movs r3, #0
+; CHECK-NEXT:    bx r1
   %1 = load i32 (i32, i64)*, i32 (i32, i64)** @fnptr4
   %2 = tail call i32 %1(i32 1, i64 2)
   ret i32 %2
@@ -96,8 +150,12 @@
 ; tail-call optimized.
 define i32 @test7() {
 ; CHECK-LABEL: test7:
-; CHECK: b bar
-; CHECK-NOT: bl bar
+; CHECK:       @ %bb.0:
+; CHECK-NEXT:    movs r0, #1
+; CHECK-NEXT:    movs r1, #2
+; CHECK-NEXT:    movs r2, #3
+; CHECK-NEXT:    movs r3, #4
+; CHECK-NEXT:    b bar
   %tail = tail call i32 @bar(i32 1, i32 2, i32 3, i32 4)
   ret i32 %tail
 }
@@ -109,6 +167,33 @@
 %struct.S = type { i32 }
 
 define void @test8(i32 (i32, i32, i32)* nocapture %fn, i32 %x) local_unnamed_addr {
+; CHECK-LABEL: test8:
+; CHECK:       @ %bb.0: @ %entry
+; CHECK-NEXT:    push {r4, r5, r6, r7, lr}
+; CHECK-NEXT:    sub sp, #4
+; CHECK-NEXT:    mov r4, r1
+; CHECK-NEXT:    str r0, [sp] @ 4-byte Spill
+; CHECK-NEXT:    bl test8_u
+; CHECK-NEXT:    mov r5, r0
+; CHECK-NEXT:    ldr r6, [r0]
+; CHECK-NEXT:    movs r7, #0
+; CHECK-NEXT:    mov r0, r7
+; CHECK-NEXT:    bl test8_h
+; CHECK-NEXT:    mov r1, r0
+; CHECK-NEXT:    mov r0, r6
+; CHECK-NEXT:    mov r2, r7
+; CHECK-NEXT:    bl test8_g
+; CHECK-NEXT:    str r4, [r5]
+; CHECK-NEXT:    movs r0, #1
+; CHECK-NEXT:    movs r1, #2
+; CHECK-NEXT:    movs r2, #3
+; CHECK-NEXT:    ldr r3, [sp] @ 4-byte Reload
+; CHECK-NEXT:    add sp, #4
+; CHECK-NEXT:    ldr r4, [sp, #16]
+; CHECK-NEXT:    mov lr, r4
+; CHECK-NEXT:    pop {r4, r5, r6, r7}
+; CHECK-NEXT:    add sp, #4
+; CHECK-NEXT:    bx r3
 entry:
   %call = tail call %struct.S* bitcast (%struct.S* (...)* @test8_u to %struct.S* ()*)()
   %a = getelementptr inbounds %struct.S, %struct.S* %call, i32 0, i32 0
@@ -125,6 +210,28 @@
 declare i32 @test8_g(i32, i32, i32)
 
 declare i32 @test8_h(i32)
-; CHECK: str r0, [sp] @ 4-byte Spill
-; CHECK: ldr r3, [sp] @ 4-byte Reload
-; CHECK: bx r3
+
+; Check that we don't introduce an unnecessary spill of lr.
+declare i32 @h9(i32, i32, i32, i32)
+define i32 @test9(i32* %x, i32* %y, i32* %z, i32* %a) {
+; CHECK-LABEL: test9:
+; CHECK:       @ %bb.0:
+; CHECK-NEXT:    push {r4, r7}
+; CHECK-NEXT:    ldr r4, [r3]
+; CHECK-NEXT:    ldr r3, [r3, #4]
+; CHECK-NEXT:    adds r3, r4, r3
+; CHECK-NEXT:    ldr r1, [r1]
+; CHECK-NEXT:    ldr r0, [r0]
+; CHECK-NEXT:    ldr r2, [r2]
+; CHECK-NEXT:    pop {r4, r7}
+; CHECK-NEXT:    b h9
+  %zz = load i32, i32* %z
+  %xx = load i32, i32* %x
+  %yy = load i32, i32* %y
+  %aa1 = load i32, i32* %a
+  %a2 = getelementptr i32, i32* %a, i32 1
+  %aa2 = load i32, i32* %a2
+  %aa = add i32 %aa1, %aa2
+  %r = tail call i32 @h9(i32 %xx, i32 %yy, i32 %zz, i32 %aa)
+  ret i32 %r
+}