[ms-inline asm] Do not omit the frame pointer if we have ms-inline assembly.

If the frame pointer is omitted, and any stack changes occur in the inline
assembly, e.g.: "pusha", then any C local variable or C argument references
will be incorrect.  

I pass no judgement on anyone who would do such a thing. ;)
rdar://13218191

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175334 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/MachineFunction.h

@@ -131,6 +131,9 @@ class MachineFunction {
   /// about the control flow of such functions.
   bool ExposesReturnsTwice;
 
+  /// True if the function includes MS-style inline assembly.
+  bool HasMSInlineAsm;
+
   MachineFunction(const MachineFunction &) LLVM_DELETED_FUNCTION;
   void operator=(const MachineFunction&) LLVM_DELETED_FUNCTION;
 public:
@@ -215,6 +218,17 @@ public:
     ExposesReturnsTwice = B;
   }
 
+  /// Returns true if the function contains any MS-style inline assembly.
+  bool hasMSInlineAsm() const {
+    return HasMSInlineAsm;
+  }
+
+  /// Set a flag that indicates that the function contains MS-style inline
+  /// assembly.
+  void setHasMSInlineAsm(bool B) {
+    HasMSInlineAsm = B;
+  }
+  
   /// getInfo - Keep track of various per-function pieces of information for
   /// backends that would like to do so.
   ///

include/llvm/CodeGen/MachineInstr.h

@@ -642,6 +642,9 @@ public:
   bool isKill() const { return getOpcode() == TargetOpcode::KILL; }
   bool isImplicitDef() const { return getOpcode()==TargetOpcode::IMPLICIT_DEF; }
   bool isInlineAsm() const { return getOpcode() == TargetOpcode::INLINEASM; }
+  bool isMSInlineAsm() const { 
+    return getOpcode() == TargetOpcode::INLINEASM && getInlineAsmDialect();
+  }
   bool isStackAligningInlineAsm() const;
   InlineAsm::AsmDialect getInlineAsmDialect() const;
   bool isInsertSubreg() const {

lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

@@ -441,25 +441,28 @@ bool SelectionDAGISel::runOnMachineFunction(MachineFunction &mf) {
   }
 
   // Determine if there are any calls in this machine function.
+  MF->setHasMSInlineAsm(false);
   MachineFrameInfo *MFI = MF->getFrameInfo();
-  if (!MFI->hasCalls()) {
-    for (MachineFunction::const_iterator
-           I = MF->begin(), E = MF->end(); I != E; ++I) {
-      const MachineBasicBlock *MBB = I;
-      for (MachineBasicBlock::const_iterator
-             II = MBB->begin(), IE = MBB->end(); II != IE; ++II) {
-        const MCInstrDesc &MCID = TM.getInstrInfo()->get(II->getOpcode());
+  for (MachineFunction::const_iterator I = MF->begin(), E = MF->end(); I != E;
+       ++I) {
 
+    if (MFI->hasCalls() && MF->hasMSInlineAsm())
+      break;
+
+    const MachineBasicBlock *MBB = I;
+    for (MachineBasicBlock::const_iterator II = MBB->begin(), IE = MBB->end();
+         II != IE; ++II) {
+      const MCInstrDesc &MCID = TM.getInstrInfo()->get(II->getOpcode());
       if ((MCID.isCall() && !MCID.isReturn()) ||
           II->isStackAligningInlineAsm()) {
         MFI->setHasCalls(true);
-          goto done;
       }
+      if (II->isMSInlineAsm()) {
+        MF->setHasMSInlineAsm(true);
       }
     }
   }
 
-  done:
   // Determine if there is a call to setjmp in the machine function.
   MF->setExposesReturnsTwice(Fn.callsFunctionThatReturnsTwice());
 

lib/Target/X86/X86FrameLowering.cpp

@@ -50,7 +50,7 @@ bool X86FrameLowering::hasFP(const MachineFunction &MF) const {
   return (MF.getTarget().Options.DisableFramePointerElim(MF) ||
           RegInfo->needsStackRealignment(MF) ||
           MFI->hasVarSizedObjects() ||
-          MFI->isFrameAddressTaken() ||
+          MFI->isFrameAddressTaken() || MF.hasMSInlineAsm() ||
           MF.getInfo<X86MachineFunctionInfo>()->getForceFramePointer() ||
           MMI.callsUnwindInit() || MMI.callsEHReturn());
 }

test/CodeGen/X86/ms-inline-asm.ll

@@ -5,6 +5,7 @@ entry:
   %0 = tail call i32 asm sideeffect inteldialect "mov eax, $1\0A\09mov $0, eax", "=r,r,~{eax},~{dirflag},~{fpsr},~{flags}"(i32 1) nounwind
   ret i32 %0
 ; CHECK: t1
+; CHECK: movl %esp, %ebp
 ; CHECK: {{## InlineAsm Start|#APP}}
 ; CHECK: .intel_syntax
 ; CHECK: mov eax, ecx
@@ -18,6 +19,7 @@ entry:
   call void asm sideeffect inteldialect "mov eax, $$1", "~{eax},~{dirflag},~{fpsr},~{flags}"() nounwind
   ret void
 ; CHECK: t2
+; CHECK: movl %esp, %ebp
 ; CHECK: {{## InlineAsm Start|#APP}}
 ; CHECK: .intel_syntax
 ; CHECK: mov eax, 1
@@ -32,6 +34,7 @@ entry:
   call void asm sideeffect inteldialect "mov eax, DWORD PTR [$0]", "*m,~{eax},~{dirflag},~{fpsr},~{flags}"(i32* %V.addr) nounwind
   ret void
 ; CHECK: t3
+; CHECK: movl %esp, %ebp
 ; CHECK: {{## InlineAsm Start|#APP}}
 ; CHECK: .intel_syntax
 ; CHECK: mov eax, DWORD PTR {{[[esp]}}
@@ -53,6 +56,7 @@ entry:
   %0 = load i32* %b1, align 4
   ret i32 %0
 ; CHECK: t18
+; CHECK: movl %esp, %ebp
 ; CHECK: {{## InlineAsm Start|#APP}}
 ; CHECK: .intel_syntax
 ; CHECK: lea ebx, foo
@@ -72,6 +76,7 @@ entry:
   call void asm sideeffect inteldialect "call $0", "r,~{dirflag},~{fpsr},~{flags}"(void ()* @t19_helper) nounwind
   ret void
 ; CHECK: t19:
+; CHECK: movl %esp, %ebp
 ; CHECK: movl ${{_?}}t19_helper, %eax
 ; CHECK: {{## InlineAsm Start|#APP}}
 ; CHECK: .intel_syntax
@@ -90,6 +95,7 @@ entry:
   %0 = load i32** %res, align 4
   ret i32* %0
 ; CHECK: t30:
+; CHECK: movl %esp, %ebp
 ; CHECK: {{## InlineAsm Start|#APP}}
 ; CHECK: .intel_syntax
 ; CHECK: lea edi, dword ptr [{{_?}}results]
@@ -97,8 +103,8 @@ entry:
 ; CHECK: {{## InlineAsm End|#NO_APP}}
 ; CHECK: {{## InlineAsm Start|#APP}}
 ; CHECK: .intel_syntax
-; CHECK: mov dword ptr [esp], edi
+; CHECK: mov dword ptr [ebp - 8], edi
 ; CHECK: .att_syntax
 ; CHECK: {{## InlineAsm End|#NO_APP}}
-; CHECK: movl (%esp), %eax
+; CHECK: movl -8(%ebp), %eax
 }