Check for dynamic allocas and inline asm that clobbers sp before building

selection dag (PR19012)

In X86SelectionDagInfo::EmitTargetCodeForMemcpy we check with MachineFrameInfo
to make sure that ESI isn't used as a base pointer register before we choose to
emit rep movs (which clobbers esi).

The problem is that MachineFrameInfo wouldn't know about dynamic allocas or
inline asm that clobbers the stack pointer until SelectionDAGBuilder has
encountered them.

This patch fixes the problem by checking for such things when building the
FunctionLoweringInfo.

Differential Revision: http://llvm-reviews.chandlerc.com/D2954

llvm-svn: 202930

1 files changed, 4 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index ed66b8205f5..406adbd6e07 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -860,10 +860,10 @@ void RegsForValue::AddInlineAsmOperands(unsigned Code, bool HasMatching,
       unsigned TheReg = Regs[Reg++];
       Ops.push_back(DAG.getRegister(TheReg, RegisterVT));
 
-      // Notice if we clobbered the stack pointer.  Yes, inline asm can do this.
       if (TheReg == SP && Code == InlineAsm::Kind_Clobber) {
-        MachineFrameInfo *MFI = DAG.getMachineFunction().getFrameInfo();
-        MFI->setHasInlineAsmWithSPAdjust(true);
+        // If we clobbered the stack pointer, MFI should know about it.
+        assert(DAG.getMachineFunction().getFrameInfo()->
+            hasInlineAsmWithSPAdjust());
       }
     }
   }
@@ -3437,9 +3437,7 @@ void SelectionDAGBuilder::visitAlloca(const AllocaInst &I) {
   setValue(&I, DSA);
   DAG.setRoot(DSA.getValue(1));
 
-  // Inform the Frame Information that we have just allocated a variable-sized
-  // object.
-  FuncInfo.MF->getFrameInfo()->CreateVariableSizedObject(Align ? Align : 1, &I);
+  assert(FuncInfo.MF->getFrameInfo()->hasVarSizedObjects());
 }
 
 void SelectionDAGBuilder::visitLoad(const LoadInst &I) {