Propagate the AlignStack bit in InlineAsm's to the

PrologEpilog code, and use it to determine whether
the asm forces stack alignment or not.  gcc consistently
does not do this for GCC-style asms; Apple gcc inconsistently
sometimes does it for asm blocks.  There is no
convenient place to put a bit in either the SDNode or
the MachineInstr form, so I've added an extra operand
to each; unlovely, but it does allow for expansion for
more bits, should we need it.  PR 5125.  Some
existing testcases are affected.
The operand lists of the SDNode and MachineInstr forms
are indexed with awesome mnemonics, like "2"; I may
fix this someday, but not now.  I'm not making it any
worse.  If anyone is inspired I think you can find all
the right places from this patch.

llvm-svn: 107506

6 files changed, 23 insertions, 12 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
index e181305ea90..f6f3bae42a8 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
@@ -279,7 +279,7 @@ void AsmPrinter::EmitInlineAsm(const MachineInstr *MI) const {
       // Okay, we finally have a value number.  Ask the target to print this
       // operand!
       if (CurVariant == -1 || CurVariant == AsmPrinterVariant) {
-        unsigned OpNo = 1;
+        unsigned OpNo = 2;
 
         bool Error = false;
 
diff --git a/llvm/lib/CodeGen/MachineInstr.cpp b/llvm/lib/CodeGen/MachineInstr.cpp
index eeea9f2e305..39ab43bb5ea 100644
--- a/llvm/lib/CodeGen/MachineInstr.cpp
+++ b/llvm/lib/CodeGen/MachineInstr.cpp
@@ -881,14 +881,14 @@ int MachineInstr::findFirstPredOperandIdx() const {
 bool MachineInstr::
 isRegTiedToUseOperand(unsigned DefOpIdx, unsigned *UseOpIdx) const {
   if (isInlineAsm()) {
-    assert(DefOpIdx >= 2);
+    assert(DefOpIdx >= 3);
     const MachineOperand &MO = getOperand(DefOpIdx);
     if (!MO.isReg() || !MO.isDef() || MO.getReg() == 0)
       return false;
     // Determine the actual operand index that corresponds to this index.
     unsigned DefNo = 0;
     unsigned DefPart = 0;
-    for (unsigned i = 1, e = getNumOperands(); i < e; ) {
+    for (unsigned i = 2, e = getNumOperands(); i < e; ) {
       const MachineOperand &FMO = getOperand(i);
       // After the normal asm operands there may be additional imp-def regs.
       if (!FMO.isImm())
@@ -903,7 +903,7 @@ isRegTiedToUseOperand(unsigned DefOpIdx, unsigned *UseOpIdx) const {
       }
       ++DefNo;
     }
-    for (unsigned i = 1, e = getNumOperands(); i != e; ++i) {
+    for (unsigned i = 2, e = getNumOperands(); i != e; ++i) {
       const MachineOperand &FMO = getOperand(i);
       if (!FMO.isImm())
         continue;
@@ -946,7 +946,7 @@ isRegTiedToDefOperand(unsigned UseOpIdx, unsigned *DefOpIdx) const {
 
     // Find the flag operand corresponding to UseOpIdx
     unsigned FlagIdx, NumOps=0;
-    for (FlagIdx = 1; FlagIdx < UseOpIdx; FlagIdx += NumOps+1) {
+    for (FlagIdx = 2; FlagIdx < UseOpIdx; FlagIdx += NumOps+1) {
       const MachineOperand &UFMO = getOperand(FlagIdx);
       // After the normal asm operands there may be additional imp-def regs.
       if (!UFMO.isImm())
@@ -964,9 +964,9 @@ isRegTiedToDefOperand(unsigned UseOpIdx, unsigned *DefOpIdx) const {
       if (!DefOpIdx)
         return true;
 
-      unsigned DefIdx = 1;
-      // Remember to adjust the index. First operand is asm string, then there
-      // is a flag for each.
+      unsigned DefIdx = 2;
+      // Remember to adjust the index. First operand is asm string, second is
+      // the AlignStack bit, then there is a flag for each.
       while (DefNo) {
         const MachineOperand &FMO = getOperand(DefIdx);
         assert(FMO.isImm());
diff --git a/llvm/lib/CodeGen/PrologEpilogInserter.cpp b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
index e92b44fcff1..62b7c21cc8a 100644
--- a/llvm/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
@@ -158,9 +158,9 @@ void PEI::calculateCallsInformation(MachineFunction &Fn) {
         AdjustsStack = true;
         FrameSDOps.push_back(I);
       } else if (I->isInlineAsm()) {
-        // An InlineAsm might be a call; assume it is to get the stack frame
-        // aligned correctly for calls.
-        AdjustsStack = true;
+        // Some inline asm's need a stack frame, as indicated by operand 1.
+        if (I->getOperand(1).getImm())
+          AdjustsStack = true;
       }
 
   MFI->setAdjustsStack(AdjustsStack);
diff --git a/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
index 0cb463dcd39..a6f63c746b7 100644
--- a/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -834,6 +834,12 @@ EmitSpecialNode(SDNode *Node, bool IsClone, bool IsCloned,
     const char *AsmStr = cast<ExternalSymbolSDNode>(AsmStrV)->getSymbol();
     MI->addOperand(MachineOperand::CreateES(AsmStr));
       
+    // Add the isAlignStack bit.
+    int64_t isAlignStack =
+      cast<ConstantSDNode>(Node->getOperand(InlineAsm::Op_IsAlignStack))->
+                          getZExtValue();
+    MI->addOperand(MachineOperand::CreateImm(isAlignStack));
+
     // Add all of the operand registers to the instruction.
     for (unsigned i = InlineAsm::Op_FirstOperand; i != NumOps;) {
       unsigned Flags =
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index c818f0d8a2d..af0a28da8fe 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -5454,6 +5454,10 @@ void SelectionDAGBuilder::visitInlineAsm(ImmutableCallSite CS) {
   const MDNode *SrcLoc = CS.getInstruction()->getMetadata("srcloc");
   AsmNodeOperands.push_back(DAG.getMDNode(SrcLoc));
 
+  // Remember the AlignStack bit as operand 3.
+  AsmNodeOperands.push_back(DAG.getTargetConstant(IA->isAlignStack() ? 1 : 0,
+                                            MVT::i1));
+
   // Loop over all of the inputs, copying the operand values into the
   // appropriate registers and processing the output regs.
   RegsForValue RetValRegs;
@@ -5642,7 +5646,7 @@ void SelectionDAGBuilder::visitInlineAsm(ImmutableCallSite CS) {
   }
 
   // Finish up input operands.  Set the input chain and add the flag last.
-  AsmNodeOperands[0] = Chain;
+  AsmNodeOperands[InlineAsm::Op_InputChain] = Chain;
   if (Flag.getNode()) AsmNodeOperands.push_back(Flag);
 
   Chain = DAG.getNode(ISD::INLINEASM, getCurDebugLoc(),
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 00e1f4f6b67..39076353a44 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -1089,6 +1089,7 @@ SelectInlineAsmMemoryOperands(std::vector<SDValue> &Ops) {
   Ops.push_back(InOps[InlineAsm::Op_InputChain]); // 0
   Ops.push_back(InOps[InlineAsm::Op_AsmString]);  // 1
   Ops.push_back(InOps[InlineAsm::Op_MDNode]);     // 2, !srcloc
+  Ops.push_back(InOps[InlineAsm::Op_IsAlignStack]);  // 3
 
   unsigned i = InlineAsm::Op_FirstOperand, e = InOps.size();
   if (InOps[e-1].getValueType() == MVT::Flag)