[ARM] Fix CPSR liveness in tMOVCCr_pseudo lowering.

[efriedma]

Summary

The lowering was missing live-ins in certain cases, like a sequence of multiple tMOVCCr_pseudo instructions. This would lead to a verifier failure, and on pre-v6 Thumb CPSR would be incorrectly clobbered.

For reasons I don't completely understand, it's hard to get a sequence of multiple tMOVCCr_pseudo instructions; the issue only seems to show up with 64-bit comparisons where the result is zero-extended. I added some extra testcases in case that changes in the future. Probably some optimization opportunities here if anyone is interested. (@test_slt_not is the case that was getting miscompiled.)

The code to check the liveness of CPSR was stolen from X86ISelLowering.cpp; maybe it could be refactored into common helper, but I have no idea where to put it.

[SjoerdMeijer]

Looks very reasonable to me.

test/CodeGen/ARM/wide-compares.ll

130

My first impression of the tests was that they could benefit from a bit of a clean-up (stack offsets, register usage, asm comments, etc.). But looks like there are 2 schools of thoughts on this. One of them being that the output of the script is okay because it is explicit, shows everything, etc. So yeah, please ignore, whatever you think is appropriate.

[efriedma]

test/CodeGen/ARM/wide-compares.ll

130

The philosophy behind update_llc_test_checks.py is that the generated code for very small functions should change infrequently, and when it does change it's easy to update the CHECK lines by just calling update_llc_test_checks.py again.

lib/Target/ARM/ARMISelLowering.cpp

BuildMI(*MBB, MI, DL, TII->get(ARM::t2Bcc))
       .addMBB(TrapBB)
       .addImm(ARMCC::EQ)
       .addReg(ARM::CPSR);
 
   MI.eraseFromParent();
   return ContBB;
 }
 
+// The CPSR operand of SelectItr might be missing a kill marker
+// because there were multiple uses of CPSR, and ISel didn't know
+// which to mark. Figure out whether SelectItr should have had a
+// kill marker, and set it if it should. Returns the correct kill
+// marker value.
+static bool checkAndUpdateCPSRKill(MachineBasicBlock::iterator SelectItr,
+                                   MachineBasicBlock* BB,
+                                   const TargetRegisterInfo* TRI) {
+  // Scan forward through BB for a use/def of CPSR.
+  MachineBasicBlock::iterator miI(std::next(SelectItr));
+  for (MachineBasicBlock::iterator miE = BB->end(); miI != miE; ++miI) {
+    const MachineInstr& mi = *miI;
+    if (mi.readsRegister(ARM::CPSR))
+      return false;
+    if (mi.definesRegister(ARM::CPSR))
+      break; // Should have kill-flag - update below.
+  }
+
+  // If we hit the end of the block, check whether CPSR is live into a
+  // successor.
+  if (miI == BB->end()) {
+    for (MachineBasicBlock::succ_iterator sItr = BB->succ_begin(),
+                                          sEnd = BB->succ_end();
+         sItr != sEnd; ++sItr) {
+      MachineBasicBlock* succ = *sItr;
+      if (succ->isLiveIn(ARM::CPSR))
+        return false;
+    }
+  }
+
+  // We found a def, or hit the end of the basic block and CPSR wasn't live
+  // out. SelectMI should have a kill flag on CPSR.
+  SelectItr->addRegisterKilled(ARM::CPSR, TRI);
+  return true;
+}
+
 MachineBasicBlock *
 ARMTargetLowering::EmitInstrWithCustomInserter(MachineInstr &MI,
                                                MachineBasicBlock *BB) const {
   const TargetInstrInfo *TII = Subtarget->getInstrInfo();
   DebugLoc dl = MI.getDebugLoc();
   bool isThumb2 = Subtarget->isThumb2();
   switch (MI.getOpcode()) {
   default: {
case ARM::tMOVCCr_pseudo: {
     //   fallthrough --> copy0MBB
     MachineBasicBlock *thisMBB  = BB;
     MachineFunction *F = BB->getParent();
     MachineBasicBlock *copy0MBB = F->CreateMachineBasicBlock(LLVM_BB);
     MachineBasicBlock *sinkMBB  = F->CreateMachineBasicBlock(LLVM_BB);
     F->insert(It, copy0MBB);
     F->insert(It, sinkMBB);
 
+    // Check whether CPSR is live past the tMOVCCr_pseudo.
+    const TargetRegisterInfo *TRI = Subtarget->getRegisterInfo();
+    if (!MI.killsRegister(ARM::CPSR) &&
+        !checkAndUpdateCPSRKill(MI, thisMBB, TRI)) {
+      copy0MBB->addLiveIn(ARM::CPSR);
+      sinkMBB->addLiveIn(ARM::CPSR);
+    }
+
     // Transfer the remainder of BB and its successor edges to sinkMBB.
     sinkMBB->splice(sinkMBB->begin(), BB,
                     std::next(MachineBasicBlock::iterator(MI)), BB->end());
     sinkMBB->transferSuccessorsAndUpdatePHIs(BB);
 
     BB->addSuccessor(copy0MBB);
     BB->addSuccessor(sinkMBB);
 

test/CodeGen/ARM/wide-compares.ll

 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=armv7-unknown-linux < %s | FileCheck --check-prefix=CHECK-ARM %s
-; RUN: llc -mtriple=thumbv6-unknown-linux < %s | FileCheck --check-prefix=CHECK-THUMB1 %s
-; RUN: llc -mtriple=thumbv7-unknown-linux < %s | FileCheck --check-prefix=CHECK-THUMB2 %s
+; RUN: llc -mtriple=armv7-unknown-linux < %s -verify-machineinstrs | FileCheck --check-prefix=CHECK-ARM %s
+; RUN: llc -mtriple=thumb-eabi < %s  -verify-machineinstrs | FileCheck --check-prefix=CHECK-THUMB1-NOMOV %s
+; RUN: llc -mtriple=thumbv6-unknown-linux < %s -verify-machineinstrs | FileCheck --check-prefix=CHECK-THUMB1 %s
+; RUN: llc -mtriple=thumbv7-unknown-linux < %s -verify-machineinstrs | FileCheck --check-prefix=CHECK-THUMB2 %s
 
 define i32 @test_slt1(i64 %a, i64 %b) {
 ; CHECK-ARM-LABEL: test_slt1:
 ; CHECK-ARM:       @ %bb.0: @ %entry
 ; CHECK-ARM-NEXT:    subs r0, r0, r2
 ; CHECK-ARM-NEXT:    mov r12, #2
 ; CHECK-ARM-NEXT:    sbcs r0, r1, r3
 ; CHECK-ARM-NEXT:    movwlt r12, #1
 ; CHECK-ARM-NEXT:    mov r0, r12
 ; CHECK-ARM-NEXT:    bx lr
 ;
+; CHECK-THUMB1-NOMOV-LABEL: test_slt1:
+; CHECK-THUMB1-NOMOV:       @ %bb.0: @ %entry
+; CHECK-THUMB1-NOMOV-NEXT:    subs r0, r0, r2
+; CHECK-THUMB1-NOMOV-NEXT:    sbcs r1, r3
+; CHECK-THUMB1-NOMOV-NEXT:    bge .LBB0_2
+; CHECK-THUMB1-NOMOV-NEXT:  @ %bb.1: @ %bb1
+; CHECK-THUMB1-NOMOV-NEXT:    movs r0, #1
+; CHECK-THUMB1-NOMOV-NEXT:    bx lr
+; CHECK-THUMB1-NOMOV-NEXT:  .LBB0_2: @ %bb2
+; CHECK-THUMB1-NOMOV-NEXT:    movs r0, #2
+; CHECK-THUMB1-NOMOV-NEXT:    bx lr
+;
 ; CHECK-THUMB1-LABEL: test_slt1:
 ; CHECK-THUMB1:       @ %bb.0: @ %entry
 ; CHECK-THUMB1-NEXT:    subs r0, r0, r2
 ; CHECK-THUMB1-NEXT:    sbcs r1, r3
 ; CHECK-THUMB1-NEXT:    bge .LBB0_2
 ; CHECK-THUMB1-NEXT:  @ %bb.1: @ %bb1
 ; CHECK-THUMB1-NEXT:    movs r0, #1
 ; CHECK-THUMB1-NEXT:    bx lr

 ; CHECK-ARM-NEXT:    bge .LBB1_2
 ; CHECK-ARM-NEXT:  @ %bb.1: @ %bb1
 ; CHECK-ARM-NEXT:    bl f
 ; CHECK-ARM-NEXT:    pop {r11, pc}
 ; CHECK-ARM-NEXT:  .LBB1_2: @ %bb2
 ; CHECK-ARM-NEXT:    bl g
 ; CHECK-ARM-NEXT:    pop {r11, pc}
 ;
+; CHECK-THUMB1-NOMOV-LABEL: test_slt2:
+; CHECK-THUMB1-NOMOV:       @ %bb.0: @ %entry
+; CHECK-THUMB1-NOMOV-NEXT:    .save {r7, lr}
+; CHECK-THUMB1-NOMOV-NEXT:    push {r7, lr}
+; CHECK-THUMB1-NOMOV-NEXT:    subs r0, r0, r2
+; CHECK-THUMB1-NOMOV-NEXT:    sbcs r1, r3
+; CHECK-THUMB1-NOMOV-NEXT:    bge .LBB1_2
+; CHECK-THUMB1-NOMOV-NEXT:  @ %bb.1: @ %bb1
+; CHECK-THUMB1-NOMOV-NEXT:    bl f
+; CHECK-THUMB1-NOMOV-NEXT:    b .LBB1_3
+; CHECK-THUMB1-NOMOV-NEXT:  .LBB1_2: @ %bb2
+; CHECK-THUMB1-NOMOV-NEXT:    bl g
+; CHECK-THUMB1-NOMOV-NEXT:  .LBB1_3: @ %bb1
+; CHECK-THUMB1-NOMOV-NEXT:    pop {r7}
+; CHECK-THUMB1-NOMOV-NEXT:    pop {r0}
+; CHECK-THUMB1-NOMOV-NEXT:    bx r0
+;
 ; CHECK-THUMB1-LABEL: test_slt2:
 ; CHECK-THUMB1:       @ %bb.0: @ %entry
 ; CHECK-THUMB1-NEXT:    push {r7, lr}
 ; CHECK-THUMB1-NEXT:    subs r0, r0, r2
 ; CHECK-THUMB1-NEXT:    sbcs r1, r3
 ; CHECK-THUMB1-NEXT:    bge .LBB1_2
 ; CHECK-THUMB1-NEXT:  @ %bb.1: @ %bb1
 ; CHECK-THUMB1-NEXT:    bl f
bb1:
   ret void
 bb2:
   call void @g()
   ret void
 }
 
 declare void @f()
 declare void @g()
+
+define i64 @test_slt_select(i64 %c, i64 %d, i64 %a, i64 %b) {
+; CHECK-ARM-LABEL: test_slt_select:
+; CHECK-ARM:       @ %bb.0: @ %entry
+; CHECK-ARM-NEXT:    push {r4, r5, r6, r7, r11, lr}
+; CHECK-ARM-NEXT:    ldr r12, [sp, #32]
+; CHECK-ARM-NEXT:    mov r6, #0
+; CHECK-ARM-NEXT:    ldr lr, [sp, #24]
+; CHECK-ARM-NEXT:    ldr r7, [sp, #36]
+; CHECK-ARM-NEXT:    ldr r5, [sp, #28]
+; CHECK-ARM-NEXT:    subs r4, lr, r12
+; CHECK-ARM-NEXT:    sbcs r7, r5, r7
+; CHECK-ARM-NEXT:    movwlo r6, #1
+; CHECK-ARM-NEXT:    cmp r6, #0
+; CHECK-ARM-NEXT:    moveq r0, r2
+; CHECK-ARM-NEXT:    moveq r1, r3
+; CHECK-ARM-NEXT:    pop {r4, r5, r6, r7, r11, pc}
+;
+; CHECK-THUMB1-NOMOV-LABEL: test_slt_select:
+; CHECK-THUMB1-NOMOV:       @ %bb.0: @ %entry
+; CHECK-THUMB1-NOMOV-NEXT:    .save {r4, r5, r6, r7, lr}
+; CHECK-THUMB1-NOMOV-NEXT:    push {r4, r5, r6, r7, lr}
+; CHECK-THUMB1-NOMOV-NEXT:    .pad #4
+; CHECK-THUMB1-NOMOV-NEXT:    sub sp, #4
+; CHECK-THUMB1-NOMOV-NEXT:    ldr r4, [sp, #36]
+; CHECK-THUMB1-NOMOV-NEXT:    ldr r5, [sp, #28]
+; CHECK-THUMB1-NOMOV-NEXT:    ldr r6, [sp, #32]
+; CHECK-THUMB1-NOMOV-NEXT:    ldr r7, [sp, #24]
+; CHECK-THUMB1-NOMOV-NEXT:    subs r6, r7, r6
+; CHECK-THUMB1-NOMOV-NEXT:    sbcs r5, r4
+; CHECK-THUMB1-NOMOV-NEXT:    blo .LBB2_2
+; CHECK-THUMB1-NOMOV-NEXT:  @ %bb.1: @ %entry
+; CHECK-THUMB1-NOMOV-NEXT:    movs r4, #0
+; CHECK-THUMB1-NOMOV-NEXT:    cmp r4, #0
+; CHECK-THUMB1-NOMOV-NEXT:    beq .LBB2_3
+; CHECK-THUMB1-NOMOV-NEXT:    b .LBB2_4
+; CHECK-THUMB1-NOMOV-NEXT:  .LBB2_2:
+; CHECK-THUMB1-NOMOV-NEXT:    movs r4, #1
+; CHECK-THUMB1-NOMOV-NEXT:    cmp r4, #0
+; CHECK-THUMB1-NOMOV-NEXT:    bne .LBB2_4
+; CHECK-THUMB1-NOMOV-NEXT:  .LBB2_3: @ %entry
+; CHECK-THUMB1-NOMOV-NEXT:    movs r0, r2
+; CHECK-THUMB1-NOMOV-NEXT:  .LBB2_4: @ %entry
+; CHECK-THUMB1-NOMOV-NEXT:    cmp r4, #0
+; CHECK-THUMB1-NOMOV-NEXT:    bne .LBB2_6
+; CHECK-THUMB1-NOMOV-NEXT:  @ %bb.5: @ %entry
+; CHECK-THUMB1-NOMOV-NEXT:    movs r1, r3
+; CHECK-THUMB1-NOMOV-NEXT:  .LBB2_6: @ %entry
+; CHECK-THUMB1-NOMOV-NEXT:    add sp, #4
+; CHECK-THUMB1-NOMOV-NEXT:    pop {r4, r5, r6, r7}
+; CHECK-THUMB1-NOMOV-NEXT:    pop {r2}
+; CHECK-THUMB1-NOMOV-NEXT:    bx r2
+;
+; CHECK-THUMB1-LABEL: test_slt_select:
+; CHECK-THUMB1:       @ %bb.0: @ %entry
+; CHECK-THUMB1-NEXT:    push {r4, r5, r6, r7, lr}
+; CHECK-THUMB1-NEXT:    sub sp, #4
+; CHECK-THUMB1-NEXT:    ldr r4, [sp, #36]
+; CHECK-THUMB1-NEXT:    ldr r5, [sp, #28]
+; CHECK-THUMB1-NEXT:    ldr r6, [sp, #32]
+; CHECK-THUMB1-NEXT:    ldr r7, [sp, #24]
+; CHECK-THUMB1-NEXT:    subs r6, r7, r6
+; CHECK-THUMB1-NEXT:    sbcs r5, r4
+; CHECK-THUMB1-NEXT:    blo .LBB2_2
+; CHECK-THUMB1-NEXT:  @ %bb.1: @ %entry
+; CHECK-THUMB1-NEXT:    movs r4, #0
+; CHECK-THUMB1-NEXT:    cmp r4, #0
+; CHECK-THUMB1-NEXT:    beq .LBB2_3
+; CHECK-THUMB1-NEXT:    b .LBB2_4
+; CHECK-THUMB1-NEXT:  .LBB2_2:
+; CHECK-THUMB1-NEXT:    movs r4, #1
+; CHECK-THUMB1-NEXT:    cmp r4, #0
+; CHECK-THUMB1-NEXT:    bne .LBB2_4
+; CHECK-THUMB1-NEXT:  .LBB2_3: @ %entry
+; CHECK-THUMB1-NEXT:    mov r0, r2
+; CHECK-THUMB1-NEXT:  .LBB2_4: @ %entry
+; CHECK-THUMB1-NEXT:    cmp r4, #0
+; CHECK-THUMB1-NEXT:    beq .LBB2_6
+; CHECK-THUMB1-NEXT:  @ %bb.5: @ %entry
+; CHECK-THUMB1-NEXT:    add sp, #4
+; CHECK-THUMB1-NEXT:    pop {r4, r5, r6, r7, pc}
+; CHECK-THUMB1-NEXT:  .LBB2_6: @ %entry
+; CHECK-THUMB1-NEXT:    mov r1, r3
+; CHECK-THUMB1-NEXT:    add sp, #4
+; CHECK-THUMB1-NEXT:    pop {r4, r5, r6, r7, pc}
+;
+; CHECK-THUMB2-LABEL: test_slt_select:
+; CHECK-THUMB2:       @ %bb.0: @ %entry
+; CHECK-THUMB2-NEXT:    push {r4, r5, r6, r7, lr}
+; CHECK-THUMB2-NEXT:    sub sp, #4
+; CHECK-THUMB2-NEXT:    ldrd r12, r7, [sp, #32]
+; CHECK-THUMB2-NEXT:    movs r6, #0
+; CHECK-THUMB2-NEXT:    ldrd lr, r5, [sp, #24]
+; CHECK-THUMB2-NEXT:    subs.w r4, lr, r12
+; CHECK-THUMB2-NEXT:    sbcs.w r7, r5, r7
+; CHECK-THUMB2-NEXT:    it lo
+; CHECK-THUMB2-NEXT:    movlo r6, #1
+; CHECK-THUMB2-NEXT:    cmp r6, #0
+; CHECK-THUMB2-NEXT:    itt eq
+; CHECK-THUMB2-NEXT:    moveq r0, r2
+; CHECK-THUMB2-NEXT:    moveq r1, r3
+; CHECK-THUMB2-NEXT:    add sp, #4
+; CHECK-THUMB2-NEXT:    pop {r4, r5, r6, r7, pc}
+entry:
+    %cmp = icmp ult i64 %a, %b
+    %r1 = select i1 %cmp, i64 %c, i64 %d
+    ret i64 %r1
+}
+
+define {i32, i32} @test_slt_not(i32 %c, i32 %d, i64 %a, i64 %b) {
+; CHECK-ARM-LABEL: test_slt_not:
+; CHECK-ARM:       @ %bb.0: @ %entry
+; CHECK-ARM-NEXT:    ldr r12, [sp]
+; CHECK-ARM-NEXT:    mov r1, #0
+; CHECK-ARM-NEXT:    ldr r0, [sp, #4]
+; CHECK-ARM-NEXT:    subs r2, r2, r12
+; CHECK-ARM-NEXT:    sbcs r0, r3, r0
+; CHECK-ARM-NEXT:    mov r0, #0
+; CHECK-ARM-NEXT:    movwge r1, #1
+; CHECK-ARM-NEXT:    movwlt r0, #1
+; CHECK-ARM-NEXT:    bx lr
+;
+; CHECK-THUMB1-NOMOV-LABEL: test_slt_not:
+; CHECK-THUMB1-NOMOV:       @ %bb.0: @ %entry
+; CHECK-THUMB1-NOMOV-NEXT:    .save {r4, r5, r7, lr}
+; CHECK-THUMB1-NOMOV-NEXT:    push {r4, r5, r7, lr}
+; CHECK-THUMB1-NOMOV-NEXT:    movs r1, #1
+; CHECK-THUMB1-NOMOV-NEXT:    movs r4, #0
+; CHECK-THUMB1-NOMOV-NEXT:    ldr r0, [sp, #20]
+; CHECK-THUMB1-NOMOV-NEXT:    ldr r5, [sp, #16]
+; CHECK-THUMB1-NOMOV-NEXT:    subs r2, r2, r5
+; CHECK-THUMB1-NOMOV-NEXT:    sbcs r3, r0
+; CHECK-THUMB1-NOMOV-NEXT:    push {r1}
+; CHECK-THUMB1-NOMOV-NEXT:    pop {r0}
+; CHECK-THUMB1-NOMOV-NEXT:    blt .LBB3_2
+; CHECK-THUMB1-NOMOV-NEXT:  @ %bb.1: @ %entry
+; CHECK-THUMB1-NOMOV-NEXT:    push {r4}
+; CHECK-THUMB1-NOMOV-NEXT:    pop {r0}
+; CHECK-THUMB1-NOMOV-NEXT:  .LBB3_2: @ %entry
+; CHECK-THUMB1-NOMOV-NEXT:    bge .LBB3_4
+; CHECK-THUMB1-NOMOV-NEXT:  @ %bb.3: @ %entry
+; CHECK-THUMB1-NOMOV-NEXT:    movs r1, r4
+; CHECK-THUMB1-NOMOV-NEXT:  .LBB3_4: @ %entry
+; CHECK-THUMB1-NOMOV-NEXT:    pop {r4, r5, r7}
+; CHECK-THUMB1-NOMOV-NEXT:    pop {r2}
+; CHECK-THUMB1-NOMOV-NEXT:    bx r2
+;
+; CHECK-THUMB1-LABEL: test_slt_not:
+; CHECK-THUMB1:       @ %bb.0: @ %entry
+; CHECK-THUMB1-NEXT:    push {r4, r5, r7, lr}
+; CHECK-THUMB1-NEXT:    movs r1, #1
+; CHECK-THUMB1-NEXT:    movs r4, #0
+; CHECK-THUMB1-NEXT:    ldr r0, [sp, #20]
+; CHECK-THUMB1-NEXT:    ldr r5, [sp, #16]
+; CHECK-THUMB1-NEXT:    subs r2, r2, r5
+; CHECK-THUMB1-NEXT:    sbcs r3, r0
+; CHECK-THUMB1-NEXT:    mov r0, r1
+; CHECK-THUMB1-NEXT:    bge .LBB3_3
+; CHECK-THUMB1-NEXT:  @ %bb.1: @ %entry
+; CHECK-THUMB1-NEXT:    blt .LBB3_4
+; CHECK-THUMB1-NEXT:  .LBB3_2: @ %entry
+; CHECK-THUMB1-NEXT:    pop {r4, r5, r7, pc}
+; CHECK-THUMB1-NEXT:  .LBB3_3: @ %entry
+; CHECK-THUMB1-NEXT:    mov r0, r4
+; CHECK-THUMB1-NEXT:    bge .LBB3_2
+; CHECK-THUMB1-NEXT:  .LBB3_4: @ %entry
+; CHECK-THUMB1-NEXT:    mov r1, r4
+; CHECK-THUMB1-NEXT:    pop {r4, r5, r7, pc}
+;
+; CHECK-THUMB2-LABEL: test_slt_not:
+; CHECK-THUMB2:       @ %bb.0: @ %entry
+; CHECK-THUMB2-NEXT:    ldr.w r12, [sp]
+; CHECK-THUMB2-NEXT:    movs r1, #0
+; CHECK-THUMB2-NEXT:    ldr r0, [sp, #4]
+; CHECK-THUMB2-NEXT:    subs.w r2, r2, r12
+; CHECK-THUMB2-NEXT:    sbcs.w r0, r3, r0
+; CHECK-THUMB2-NEXT:    mov.w r0, #0
+; CHECK-THUMB2-NEXT:    ite lt
+; CHECK-THUMB2-NEXT:    movlt r0, #1
+; CHECK-THUMB2-NEXT:    movge r1, #1
+; CHECK-THUMB2-NEXT:    bx lr
+entry:
+    %cmp = icmp slt i64 %a, %b
+    %not = xor i1 %cmp, true
+    %r1 = zext i1 %cmp to i32
+    %r2 = zext i1 %not to i32
+    %z = insertvalue { i32, i32 } undef, i32 %r1, 0
+    %z2 = insertvalue { i32, i32 } %z, i32 %r2, 1
+    ret { i32, i32 } %z2
+}

test/CodeGen/Thumb/select.ll

-; RUN: llc < %s -mtriple=thumb-apple-darwin | FileCheck %s
-; RUN: llc < %s -mtriple=thumb-pc-linux-gnueabi | FileCheck -check-prefix=CHECK-EABI %s
+; RUN: llc < %s -mtriple=thumb-apple-darwin -verify-machineinstrs | FileCheck %s
+; RUN: llc < %s -mtriple=thumb-pc-linux-gnueabi -verify-machineinstrs | FileCheck -check-prefix=CHECK-EABI %s
 
 define i32 @f1(i32 %a.s) {
 entry:
     %tmp = icmp eq i32 %a.s, 4
     %tmp1.s = select i1 %tmp, i32 2, i32 3
     ret i32 %tmp1.s
 }
 ; CHECK-LABEL: f1:

 ; CHECK-LABEL: f7:
 ; CHECK: {{blt|bge}}
 ; CHECK: {{blt|bge}}
 ; CHECK: __ltdf2
 ; CHECK-EABI-LABEL: f7:
 ; CHECK-EABI: __aeabi_dcmplt
 ; CHECK-EABI: {{bne|beq}}
 ; CHECK-EABI: {{bne|beq}}
+
+define {i32, i32} @f8(i32 %a, i32 %b, i32 %c, i32 %d) {
+entry:
+    %cmp = icmp slt i32 %a, %b
+    %r1 = select i1 %cmp, i32 %c, i32 %a
+    %r2 = select i1 %cmp, i32 %d, i32 %b
+    %z = insertvalue { i32, i32 } undef, i32 %r1, 0
+    %z2 = insertvalue { i32, i32 } %z, i32 %r2, 1
+    ret { i32, i32 } %z2
+}
+
+; CHECK-LABEL: f8:
+; CHECK: cmp r0, r1
+; CHECK: blt
+; CHECK: movs
+; CHECK: cmp r0, r1
+; CHECK: blt
+; CHECK: movs
+; CHECK: movs
+; CHECK: movs
+; CHECK: bx lr