[llvm] r323940 - [XRay][compiler-rt+llvm] Update XRay register stashing semantics

[Dean Michael Berris via llvm-commits]

Author: dberris
Date: Wed Jan 31 18:21:54 2018
New Revision: 323940

URL: http://llvm.org/viewvc/llvm-project?rev=323940&view=rev
Log:
[XRay][compiler-rt+llvm] Update XRay register stashing semantics

Summary:
This change expands the amount of registers stashed by the entry and
`__xray_CustomEvent` trampolines.

We've found that since the `__xray_CustomEvent` trampoline calls can show up in
situations where the scratch registers are being used, and since we don't
typically want to affect the code-gen around the disabled
`__xray_customevent(...)` intrinsic calls, that we need to save and restore the
state of even the scratch registers in the handling of these custom events.

Reviewers: pcc, pelikan, dblaikie, eizan, kpw, echristo, chandlerc

Reviewed By: echristo

Subscribers: chandlerc, echristo, hiraditya, davide, dblaikie, llvm-commits

Differential Revision: https://reviews.llvm.org/D40894

Modified:
    llvm/trunk/include/llvm/CodeGen/TargetLowering.h
    llvm/trunk/lib/CodeGen/SelectionDAG/FastISel.cpp
    llvm/trunk/lib/CodeGen/TargetLoweringBase.cpp
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

Modified: llvm/trunk/include/llvm/CodeGen/TargetLowering.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/TargetLowering.h?rev=323940&r1=323939&r2=323940&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/TargetLowering.h (original)
+++ llvm/trunk/include/llvm/CodeGen/TargetLowering.h Wed Jan 31 18:21:54 2018
@@ -2532,6 +2532,11 @@ protected:
   /// sequence of memory operands that is recognized by PrologEpilogInserter.
   MachineBasicBlock *emitPatchPoint(MachineInstr &MI,
                                     MachineBasicBlock *MBB) const;
+
+  /// Replace/modify the XRay custom event operands with target-dependent
+  /// details.
+  MachineBasicBlock *emitXRayCustomEvent(MachineInstr &MI,
+                                         MachineBasicBlock *MBB) const;
 };
 
 /// This class defines information used to lower LLVM code to legal SelectionDAG

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/FastISel.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/FastISel.cpp?rev=323940&r1=323939&r2=323940&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/FastISel.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/FastISel.cpp Wed Jan 31 18:21:54 2018
@@ -874,6 +874,7 @@ bool FastISel::selectXRayCustomEvent(con
               TII.get(TargetOpcode::PATCHABLE_EVENT_CALL));
   for (auto &MO : Ops)
     MIB.add(MO);
+
   // Insert the Patchable Event Call instruction, that gets lowered properly.
   return true;
 }

Modified: llvm/trunk/lib/CodeGen/TargetLoweringBase.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/TargetLoweringBase.cpp?rev=323940&r1=323939&r2=323940&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/TargetLoweringBase.cpp (original)
+++ llvm/trunk/lib/CodeGen/TargetLoweringBase.cpp Wed Jan 31 18:21:54 2018
@@ -985,6 +985,21 @@ TargetLoweringBase::emitPatchPoint(Machi
   return MBB;
 }
 
+MachineBasicBlock *
+TargetLoweringBase::emitXRayCustomEvent(MachineInstr &MI,
+                                        MachineBasicBlock *MBB) const {
+  assert(MI.getOpcode() == TargetOpcode::PATCHABLE_EVENT_CALL &&
+         "Called emitXRayCustomEvent on the wrong MI!");
+  auto &MF = *MI.getMF();
+  auto MIB = BuildMI(MF, MI.getDebugLoc(), MI.getDesc());
+  for (unsigned OpIdx = 0; OpIdx != MI.getNumOperands(); ++OpIdx)
+    MIB.add(MI.getOperand(OpIdx));
+
+  MBB->insert(MachineBasicBlock::iterator(MI), MIB);
+  MI.eraseFromParent();
+  return MBB;
+}
+
 /// findRepresentativeClass - Return the largest legal super-reg register class
 /// of the register class for the specified type and its associated "cost".
 // This function is in TargetLowering because it uses RegClassForVT which would

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=323940&r1=323939&r2=323940&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Wed Jan 31 18:21:54 2018
@@ -27878,8 +27878,7 @@ X86TargetLowering::EmitInstrWithCustomIn
     return emitPatchPoint(MI, BB);
 
   case TargetOpcode::PATCHABLE_EVENT_CALL:
-    // Do nothing here, handle in xray instrumentation pass.
-    return BB;
+    return emitXRayCustomEvent(MI, BB);
 
   case X86::LCMPXCHG8B: {
     const X86RegisterInfo *TRI = Subtarget.getRegisterInfo();