Fix the lowering issue of intrinsics llvm.localaddress on X86

[rnk]

lib/Target/X86/X86ISelLowering.cpp

22363 ↗

(On Diff #184459)

Why doesn't this already work? The comment exists just to point out that getPtrSizedFrameRegister will sometimes select SP based on exactly the condition you've listed here, unless I'm mistaken.

[LuoYuanke]

lib/Target/X86/X86ISelLowering.cpp

22363 ↗

(On Diff #184459)

I think when stack is realigned, compiler choose sp as base to access local variable, however bp is still used to recover sp when return from the function.

[rnk]

lgtm

lib/Target/X86/X86ISelLowering.cpp

22363 ↗

(On Diff #184459)

I see the issue, hasFP is true for this function, but SP is used to address local variables.

llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

SDValue X86TargetLowering::LowerINTRINSIC_WO_CHAIN(SDValue Op,
   case Intrinsic::localaddress: {
     // Returns one of the stack, base, or frame pointer registers, depending on
     // which is used to reference local variables.
     MachineFunction &MF = DAG.getMachineFunction();
     const X86RegisterInfo *RegInfo = Subtarget.getRegisterInfo();
     unsigned Reg;
     if (RegInfo->hasBasePointer(MF))
       Reg = RegInfo->getBaseRegister();
-    else // This function handles the SP or FP case.
+    else { // Handles the SP or FP case.
+      bool CantUseFP = RegInfo->needsStackRealignment(MF);
+      if (CantUseFP)
+        Reg = RegInfo->getPtrSizedStackRegister(MF);
+      else
         Reg = RegInfo->getPtrSizedFrameRegister(MF);
+    }
     return DAG.getCopyFromReg(DAG.getEntryNode(), dl, Reg, VT);
   }
   }
 }
 
 static SDValue getAVX2GatherNode(unsigned Opc, SDValue Op, SelectionDAG &DAG,
                                  SDValue Src, SDValue Mask, SDValue Base,
                                  SDValue Index, SDValue ScaleOp, SDValue Chain,

llvm/trunk/lib/Target/X86/X86RegisterInfo.h

public:
 
   void eliminateFrameIndex(MachineBasicBlock::iterator MI,
                            int SPAdj, unsigned FIOperandNum,
                            RegScavenger *RS = nullptr) const override;
 
   // Debug information queries.
   unsigned getFrameRegister(const MachineFunction &MF) const override;
   unsigned getPtrSizedFrameRegister(const MachineFunction &MF) const;
+  unsigned getPtrSizedStackRegister(const MachineFunction &MF) const;
   unsigned getStackRegister() const { return StackPtr; }
   unsigned getBaseRegister() const { return BasePtr; }
   /// Returns physical register used as frame pointer.
   /// This will always returns the frame pointer register, contrary to
   /// getFrameRegister() which returns the "base pointer" in situations
   /// involving a stack, frame and base pointer.
   unsigned getFramePtr() const { return FramePtr; }
   // FIXME: Move to FrameInfok
   unsigned getSlotSize() const { return SlotSize; }
 };
 
 } // End llvm namespace
 
 #endif

llvm/trunk/lib/Target/X86/X86RegisterInfo.cpp

 unsigned
 X86RegisterInfo::getPtrSizedFrameRegister(const MachineFunction &MF) const {
   const X86Subtarget &Subtarget = MF.getSubtarget<X86Subtarget>();
   unsigned FrameReg = getFrameRegister(MF);
   if (Subtarget.isTarget64BitILP32())
     FrameReg = getX86SubSuperRegister(FrameReg, 32);
   return FrameReg;
 }
+
+unsigned
+X86RegisterInfo::getPtrSizedStackRegister(const MachineFunction &MF) const {
+  const X86Subtarget &Subtarget = MF.getSubtarget<X86Subtarget>();
+  unsigned StackReg = getStackRegister();
+  if (Subtarget.isTarget64BitILP32())
+    StackReg = getX86SubSuperRegister(StackReg, 32);
+  return StackReg;
+}

llvm/trunk/test/CodeGen/X86/seh-localaddress.ll

+; RUN: llc -mtriple x86_64-pc-windows-msvc -o - %s | FileCheck %s
+
+; struct S { int x; };
+; void foo() {
+;   struct S __declspec(align(32)) o;
+;   __try { o.x; }
+;   __finally { o.x; }
+; }
+; void bar() {
+;   struct S o;
+;   __try { o.x; }
+;   __finally { o.x; }
+; }
+
+%struct.S = type { i32 }
+
+define dso_local void @"?foo@@YAXXZ"() #0 {
+entry:
+; CHECK-LABEL: foo
+; CHECK: movq  %rsp, %rdx
+; CHECK-NOT: movq  %rbp, %rdx
+
+  %o = alloca %struct.S, align 32
+  call void (...) @llvm.localescape(%struct.S* %o)
+  %x = getelementptr inbounds %struct.S, %struct.S* %o, i32 0, i32 0
+  %0 = call i8* @llvm.localaddress()
+  call void @"?fin$0@0@foo@@"(i8 0, i8* %0)
+  ret void
+}
+
+; void bar(void)
+; {
+;   int x;
+;   void (*fn)(int);
+;
+;   __try {
+;     x = 1;
+;     fn(x);
+;   } __finally {
+;     x = 2;
+;   }
+; }
+
+define dso_local void @"?bar@@YAXXZ"() personality i8* bitcast (i32 (...)* @__C_specific_handler to i8*) {
+entry:
+; CHECK-LABEL: bar
+; CHECK: movq  %rbp, %rdx
+; CHECK-NOT: movq  %rsp, %rdx
+  %x = alloca i32, align 4
+  %fn = alloca void (i32)*, align 8
+  call void (...) @llvm.localescape(i32* %x)
+  store i32 1, i32* %x, align 4
+  %0 = load void (i32)*, void (i32)** %fn, align 8
+  %1 = load i32, i32* %x, align 4
+  invoke void %0(i32 %1)
+  to label %invoke.cont unwind label %ehcleanup
+  invoke.cont:                                      ; preds = %entry
+  %2 = call i8* @llvm.localaddress()
+  call void @"?fin$0@0@bar@@"(i8 0, i8* %2)
+  ret void
+  ehcleanup:                                        ; preds = %entry
+  %3 = cleanuppad within none []
+  %4 = call i8* @llvm.localaddress()
+  call void @"?fin$0@0@bar@@"(i8 1, i8* %4) [ "funclet"(token %3) ]
+  cleanupret from %3 unwind to caller
+}
+
+declare void @"?fin$0@0@foo@@"(i8 %abnormal_termination, i8* %frame_pointer)
+
+declare void @"?fin$0@0@bar@@"(i8 %abnormal_termination, i8* %frame_pointer)
+
+declare i8* @llvm.localrecover(i8*, i8*, i32)
+
+declare i8* @llvm.localaddress()
+
+declare void @llvm.localescape(...)
+
+declare dso_local i32 @__C_specific_handler(...)