Fix the side effect of outlined function when the register is implicit use and implicit-def in the same instruction.

This is the diff associated with {D95267}, and we need to mark $x0 as live whether or not $x0 is dead.

The compiler also needs to mark register $x0 as live in for the following case.

```
$x1 = ADDXri $sp, 16, 0
BL @spam, csr_darwin_aarch64_aapcs, implicit-def dead $lr, implicit $sp, implicit $x0, implicit killed $x1, implicit-def $sp, implicit-def $x0
```

This change fixes an issue where the wrong registers were used when -machine-outliner-reruns>0.
As an example:

```
lang=c
typedef struct {
    double v1;
    double v2;
} D16;

typedef struct {
    D16 v1;
    D16 v2;
} D32;

typedef long long LL8;
typedef struct {
    long long v1;
    long long v2;
} LL16;
typedef struct {
    LL16 v1;
    LL16 v2;
} LL32;

typedef struct {
    LL32 v1;
    LL32 v2;
} LL64;

LL8 needx0(LL8 v0, LL8 v1);

void bar(LL64 v1, LL32 v2, LL16 v3, LL32 v4, LL8 v5, D16 v6, D16 v7, D16 v8);

LL8 foo(LL8 v0, LL64 v1, LL32 v2, LL16 v3, LL32 v4, LL8 v5, D16 v6, D16 v7, D16 v8)
{
  LL8 result = needx0(v0, 0);
  bar(v1, v2, v3, v4, v5, v6, v7, v8);
  return result + 1;
}
```

As you can see from the `foo` function, we should not modify the value of `x0` until we call `needx0`.
This code is compiled to give the following instruction MIR code.

```
$sp = frame-setup SUBXri $sp, 256, 0
frame-setup STPDi killed $d13, killed $d12, $sp, 16
frame-setup STPDi killed $d11, killed $d10, $sp, 18
frame-setup STPDi killed $d9, killed $d8, $sp, 20

frame-setup STPXi killed $x26, killed $x25, $sp, 22
frame-setup STPXi killed $x24, killed $x23, $sp, 24
frame-setup STPXi killed $x22, killed $x21, $sp, 26
frame-setup STPXi killed $x20, killed $x19, $sp, 28
...
$x1 = MOVZXi 0, 0
BL @needx0, csr_darwin_aarch64_aapcs, implicit-def dead $lr, implicit $sp, implicit $x0, implicit $x1, implicit-def $sp, implicit-def $x0
...
```

Since there are some other instruction sequences that duplicate `foo`, after the first execution of Machine Outliner you will get:
```
$sp = frame-setup SUBXri $sp, 256, 0
frame-setup STPDi killed $d13, killed $d12, $sp, 16
frame-setup STPDi killed $d11, killed $d10, $sp, 18
frame-setup STPDi killed $d9, killed $d8, $sp, 20

$x7 = ORRXrs $xzr, $lr, 0
BL @OUTLINED_FUNCTION_0, implicit-def $lr, implicit $sp, implicit-def $lr, implicit $sp, implicit $xzr, implicit $x7, implicit $x19, implicit $x20, implicit $x21, implicit $x22, implicit $x23, implicit $x24, implicit $x25, implicit $x26
$lr = ORRXrs $xzr, $x7, 0
...
BL @OUTLINED_FUNCTION_1, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $sp, implicit-def $x0, implicit-def $x1, implicit $sp
...
```

For the first time we outlined the following sequence:
```
frame-setup STPXi killed $x26, killed $x25, $sp, 22
frame-setup STPXi killed $x24, killed $x23, $sp, 24
frame-setup STPXi killed $x22, killed $x21, $sp, 26
frame-setup STPXi killed $x20, killed $x19, $sp, 28
```
and
```
$x1 = MOVZXi 0, 0
BL @needx0, csr_darwin_aarch64_aapcs, implicit-def dead $lr, implicit $sp, implicit $x0, implicit $x1, implicit-def $sp, implicit-def $x0
```

When we execute the outline again, we will get:
```
$x0 = ORRXrs $xzr, $lr, 0 <---- here
BL @OUTLINED_FUNCTION_2_0, implicit-def $lr, implicit $sp, implicit-def $sp, implicit-def $lr, implicit $sp, implicit $xzr, implicit $d8, implicit $d9, implicit $d10, implicit $d11, implicit $d12, implicit $d13, implicit $x0
$lr = ORRXrs $xzr, $x0, 0

$x7 = ORRXrs $xzr, $lr, 0
BL @OUTLINED_FUNCTION_0, implicit-def $lr, implicit $sp, implicit-def $lr, implicit $sp, implicit $xzr, implicit $x7, implicit $x19, implicit $x20, implicit $x21, implicit $x22, implicit $x23, implicit $x24, implicit $x25, implicit $x26
$lr = ORRXrs $xzr, $x7, 0
...
BL @OUTLINED_FUNCTION_1, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $sp, implicit-def $x0, implicit-def $x1, implicit $sp
```

When calling `OUTLINED_FUNCTION_2_0`, we used `x0` to save the `lr` register.
The reason for the above error appears to be that:
```
BL @OUTLINED_FUNCTION_1, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $sp, implicit-def $x0, implicit-def $x1, implicit $sp
```
should be:
```
BL @OUTLINED_FUNCTION_1, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $sp, implicit-def $x0, implicit-def $x1, implicit $sp, implicit $x0
```

When processing the same instruction with both `implicit-def $x0` and `implicit $x0` we should keep `implicit $x0`.
A reproducible demo is available at: [https://github.com/DianQK/reproduce_outlined_function_use_live_x0](https://github.com/DianQK/reproduce_outlined_function_use_live_x0).

Reviewed By: jinlin

Differential Revision: https://reviews.llvm.org/D112911

Author: dianqk

llvm/lib/CodeGen/MachineOutliner.cpp

@@ -798,6 +798,7 @@ bool MachineOutliner::outline(Module &M,
                  Last = std::next(CallInst.getReverse());
              Iter != Last; Iter++) {
           MachineInstr *MI = &*Iter;
+          SmallSet<Register, 2> InstrUseRegs;
           for (MachineOperand &MOP : MI->operands()) {
             // Skip over anything that isn't a register.
             if (!MOP.isReg())
@@ -806,14 +807,16 @@ bool MachineOutliner::outline(Module &M,
             if (MOP.isDef()) {
               // Introduce DefRegs set to skip the redundant register.
               DefRegs.insert(MOP.getReg());
-              if (!MOP.isDead() && UseRegs.count(MOP.getReg()))
+              if (UseRegs.count(MOP.getReg()) &&
+                  !InstrUseRegs.count(MOP.getReg()))
                 // Since the regiester is modeled as defined,
                 // it is not necessary to be put in use register set.
                 UseRegs.erase(MOP.getReg());
             } else if (!MOP.isUndef()) {
               // Any register which is not undefined should
               // be put in the use register set.
               UseRegs.insert(MOP.getReg());
+              InstrUseRegs.insert(MOP.getReg());
             }
           }
           if (MI->isCandidateForCallSiteEntry())

llvm/test/CodeGen/AArch64/machine-outliner-side-effect-2.mir

@@ -1,6 +1,7 @@
 # RUN: llc -mtriple=aarch64 -run-pass=machine-outliner -verify-machineinstrs %s -o - | FileCheck %s
 
-# The test checks whether the compiler updates the side effect of function @OUTLINED_FUNCTION_0 by adding the use of register x0.
+# The test checks whether the compiler updates the side effect of function @OUTLINED_FUNCTION_0
+# when implict-def and implict use of $x0 in the same instruction.
 
 --- |
   declare void @spam() local_unnamed_addr
@@ -16,7 +17,8 @@ body:             |
     liveins: $x0, $lr
 
     $x1 = ADDXri $sp, 16, 0
-    BL @spam, csr_darwin_aarch64_aapcs, implicit-def dead $lr, implicit $sp, implicit $x0, implicit killed $x1, implicit-def $sp, implicit-def dead $x0
+    BL @spam, csr_darwin_aarch64_aapcs, implicit-def dead $lr, implicit $sp, implicit $x0, implicit killed $x1, implicit-def $sp, implicit-def $x0
+    renamable $x1 = COPY $x0
 
     RET_ReallyLR
 
@@ -29,7 +31,8 @@ body:             |
     liveins: $x0, $lr
 
     $x1 = ADDXri $sp, 16, 0
-    BL @spam, csr_darwin_aarch64_aapcs, implicit-def dead $lr, implicit $sp, implicit $x0, implicit killed $x1, implicit-def $sp, implicit-def dead $x0
+    BL @spam, csr_darwin_aarch64_aapcs, implicit-def dead $lr, implicit $sp, implicit $x0, implicit killed $x1, implicit-def $sp, implicit-def $x0
+    renamable $x2 = COPY $x0
 
     RET_ReallyLR
 
@@ -42,10 +45,11 @@ body:             |
     liveins: $x0, $lr
 
     $x1 = ADDXri $sp, 16, 0
-    BL @spam, csr_darwin_aarch64_aapcs, implicit-def dead $lr, implicit $sp, implicit $x0, implicit killed $x1, implicit-def $sp, implicit-def dead $x0
+    BL @spam, csr_darwin_aarch64_aapcs, implicit-def dead $lr, implicit $sp, implicit $x0, implicit killed $x1, implicit-def $sp, implicit-def $x0
+    renamable $x3 = COPY $x0
 
     RET_ReallyLR
 
 ...
 
-# CHECK: BL @OUTLINED_FUNCTION_0, {{.*}}, implicit $x0
+# CHECK: BL @OUTLINED_FUNCTION_0, {{.*}}, implicit $x0{{.*}}

llvm/test/CodeGen/AArch64/machine-outliner-side-effect.mir

@@ -29,4 +29,4 @@ body:             |
 
 ...
 
-# CHECK: BL @OUTLINED_FUNCTION_0, {{.*}}, implicit $x20, {{.*}}
+# CHECK: BL @OUTLINED_FUNCTION_0, {{.*}}, implicit $x20{{.*}}