[llvm] 02c154a - [AArch64][MachineOutliner] Don't outline CFI instructions

[Jessica Paquette via llvm-commits]

Author: Jessica Paquette
Date: 2020-03-02T10:56:35-08:00
New Revision: 02c154a9cb7f81d6bffe2326104e8d19980f2dd5

URL: https://github.com/llvm/llvm-project/commit/02c154a9cb7f81d6bffe2326104e8d19980f2dd5
DIFF: https://github.com/llvm/llvm-project/commit/02c154a9cb7f81d6bffe2326104e8d19980f2dd5.diff

LOG: [AArch64][MachineOutliner] Don't outline CFI instructions

CFI instructions can only safely be outlined when the outlined call is a tail
call, or when the outlined frame is fixed up.

For the sake of correctness, disable outlining from CFI instructions.

Add machine-outliner-cfi.mir to test this.

Added: 
    llvm/test/CodeGen/AArch64/machine-outliner-cfi.mir

Modified: 
    llvm/lib/Target/AArch64/AArch64InstrInfo.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
index 472b5e628e19..436b26c36d2d 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -6158,6 +6158,14 @@ AArch64InstrInfo::getOutliningType(MachineBasicBlock::iterator &MIT,
   if (FuncInfo->getLOHRelated().count(&MI))
     return outliner::InstrType::Illegal;
 
+  // We can only outline these if we will tail call the outlined function, or
+  // fix up the CFI offsets. For the sake of safety, don't outline CFI
+  // instructions.
+  //
+  // FIXME: If the proper fixups are implemented, this should be possible.
+  if (MI.isCFIInstruction())
+    return outliner::InstrType::Illegal;
+
   // Don't allow debug values to impact outlining type.
   if (MI.isDebugInstr() || MI.isIndirectDebugValue())
     return outliner::InstrType::Invisible;

diff  --git a/llvm/test/CodeGen/AArch64/machine-outliner-cfi.mir b/llvm/test/CodeGen/AArch64/machine-outliner-cfi.mir
new file mode 100644
index 000000000000..707785a566a2
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/machine-outliner-cfi.mir
@@ -0,0 +1,63 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=aarch64-apple-unknown -run-pass=machine-outliner -verify-machineinstrs %s -o - | FileCheck %s
+
+# Outlining CFI instructions is unsafe. It is possible if the call is tail
+# called, but otherwise, it requires fixups. Show that we don't include CFI
+# instructions in outlined sequences right now.
+
+--- |
+  define void @foo() #0 { ret void }
+  define void @bar() #0 { ret void }
+  define void @baz() #0 { ret void }
+  attributes #0 = { noredzone }
+...
+---
+name:            foo
+tracksRegLiveness: true
+body:             |
+  bb.0:
+  liveins: $lr
+    ; CHECK-LABEL: name: foo
+    ; CHECK: liveins: $lr
+    ; CHECK: frame-setup CFI_INSTRUCTION def_cfa $w29, 16
+    ; CHECK: TCRETURNdi @OUTLINED_FUNCTION_0, 0, implicit $sp, implicit-def $w12, implicit-def $w13, implicit-def $w14, implicit-def $w15
+    frame-setup CFI_INSTRUCTION def_cfa $w29, 16
+    $w12 = ORRWri $wzr, 1
+    $w13 = ORRWri $wzr, 2
+    $w14 = ORRWri $wzr, 3
+    $w15 = ORRWri $wzr, 4
+    RET undef $lr
+...
+---
+name:            bar
+tracksRegLiveness: true
+body:             |
+  bb.0:
+  liveins: $lr
+    ; CHECK-LABEL: name: bar
+    ; CHECK: liveins: $lr
+    ; CHECK: frame-setup CFI_INSTRUCTION def_cfa $w29, 16
+    ; CHECK: TCRETURNdi @OUTLINED_FUNCTION_0, 0, implicit $sp, implicit-def $w12, implicit-def $w13, implicit-def $w14, implicit-def $w15
+    frame-setup CFI_INSTRUCTION def_cfa $w29, 16
+    $w12 = ORRWri $wzr, 1
+    $w13 = ORRWri $wzr, 2
+    $w14 = ORRWri $wzr, 3
+    $w15 = ORRWri $wzr, 4
+    RET undef $lr
+...
+---
+name:            baz
+tracksRegLiveness: true
+body:             |
+  bb.0:
+  liveins: $lr
+    ; CHECK-LABEL: name: baz
+    ; CHECK: liveins: $lr
+    ; CHECK: frame-setup CFI_INSTRUCTION def_cfa $w29, 16
+    ; CHECK: TCRETURNdi @OUTLINED_FUNCTION_0, 0, implicit $sp, implicit-def $w12, implicit-def $w13, implicit-def $w14, implicit-def $w15
+    frame-setup CFI_INSTRUCTION def_cfa $w29, 16
+    $w12 = ORRWri $wzr, 1
+    $w13 = ORRWri $wzr, 2
+    $w14 = ORRWri $wzr, 3
+    $w15 = ORRWri $wzr, 4
+    RET undef $lr