[MachineOutliner] AArch64: Emit CFI instructions when outlining calls

When outlining calls, the outliner needs to update CFI to ensure that, say,
exception handling works. This commit adds that functionality and adds a test
just for call outlining.

Call outlining stuff in machine-outliner.mir should be moved into
machine-outliner-calls.mir in a later commit.

llvm-svn: 327917

llvm/lib/Target/AArch64/AArch64InstrInfo.cpp

@@ -5282,6 +5282,25 @@ void AArch64InstrInfo::insertOutlinerEpilogue(
                                 .addImm(-16);
     It = MBB.insert(It, STRXpre);
 
+    const TargetSubtargetInfo &STI = MF.getSubtarget();
+    const MCRegisterInfo *MRI = STI.getRegisterInfo();
+    unsigned DwarfReg = MRI->getDwarfRegNum(AArch64::LR, true);
+
+    // Add a CFI saying the stack was moved 16 B down.
+    int64_t StackPosEntry =
+        MF.addFrameInst(MCCFIInstruction::createDefCfaOffset(nullptr, 16));
+    BuildMI(MBB, It, DebugLoc(), get(AArch64::CFI_INSTRUCTION))
+        .addCFIIndex(StackPosEntry)
+        .setMIFlags(MachineInstr::FrameSetup);
+
+    // Add a CFI saying that the LR that we want to find is now 16 B higher than
+    // before.
+    int64_t LRPosEntry =
+        MF.addFrameInst(MCCFIInstruction::createOffset(nullptr, DwarfReg, 16));
+    BuildMI(MBB, It, DebugLoc(), get(AArch64::CFI_INSTRUCTION))
+        .addCFIIndex(LRPosEntry)
+        .setMIFlags(MachineInstr::FrameSetup);
+
     // Insert a restore before the terminator for the function.
     MachineInstr *LDRXpost = BuildMI(MF, DebugLoc(), get(AArch64::LDRXpost))
                                  .addReg(AArch64::SP, RegState::Define)

llvm/test/CodeGen/AArch64/machine-outliner-calls.mir

@@ -0,0 +1,67 @@
+# RUN: llc -simplify-mir -mtriple=aarch64--- -run-pass=machine-outliner -verify-machineinstrs %s -o - | FileCheck %s
+--- |
+  define void @baz() #0 {
+    ret void
+  }
+  
+  define void @bar(i32 %a) #0 {
+    ret void
+  }
+  
+  attributes #0 = { noredzone }
+...
+---
+
+name:            bar
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $w0, $lr, $w8
+    $sp = frame-setup SUBXri $sp, 32, 0
+    $fp = frame-setup ADDXri $sp, 16, 0
+
+  bb.1:
+    BL @baz, implicit-def dead $lr, implicit $sp
+    $w17 = ORRWri $wzr, 1
+    $w17 = ORRWri $wzr, 1
+    $w0 = ORRWri $wzr, 4
+
+    BL @baz, implicit-def dead $lr, implicit $sp
+    $w17 = ORRWri $wzr, 1
+    $w17 = ORRWri $wzr, 1
+    $w0 = ORRWri $wzr, 3
+    
+    BL @baz, implicit-def dead $lr, implicit $sp
+    $w17 = ORRWri $wzr, 1
+    $w17 = ORRWri $wzr, 1
+    $w0 = ORRWri $wzr, 2
+
+    BL @baz, implicit-def dead $lr, implicit $sp
+    $w17 = ORRWri $wzr, 1
+    $w17 = ORRWri $wzr, 1
+    $w0 = ORRWri $wzr, 1
+    
+
+  bb.2:
+    $fp, $lr = LDPXi $sp, 2
+    RET undef $lr
+...
+---
+name:            baz
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $w0, $lr, $w8
+    RET undef $lr
+
+# CHECK: name:            OUTLINED_FUNCTION_0
+# CHECK-DAG: bb.0:
+# CHECK-NEXT: liveins: $lr
+# CHECK-DAG: frame-setup CFI_INSTRUCTION def_cfa_offset -16
+# CHECK-NEXT: frame-setup CFI_INSTRUCTION offset $w30, 16
+# CHECK-NEXT: early-clobber $sp = STRXpre $lr, $sp, -16
+# CHECK-NEXT: BL @baz, implicit-def dead $lr, implicit $sp
+# CHECK-NEXT: $w17 = ORRWri $wzr, 1
+# CHECK-NEXT: $w17 = ORRWri $wzr, 1
+# CHECK-NEXT: early-clobber $sp, $lr = LDRXpost $sp, 16
+# CHECK-NEXT: RET undef $lr