Make sure the start of the arg area and the end (after the RA is pushed)
is always 8-byte aligned for fastcc
llvm-svn: 21995
diff --git a/llvm/lib/Target/X86/X86ISelPattern.cpp b/llvm/lib/Target/X86/X86ISelPattern.cpp
index fe1967f..3281cc2 100644
--- a/llvm/lib/Target/X86/X86ISelPattern.cpp
+++ b/llvm/lib/Target/X86/X86ISelPattern.cpp
@@ -385,6 +385,10 @@
// and requires that the callee pop its arguments off the stack (allowing proper
// tail calls), and has the same return value conventions as C calling convs.
//
+// This calling convention always arranges for the callee pop value to be 8n+4
+// bytes, which is needed for tail recursion elimination and stack alignment
+// reasons.
+//
// Note that this can be enhanced in the future to pass fp vals in registers
// (when we have a global fp allocator) and do other tricks.
//
@@ -533,6 +537,11 @@
ArgOffset += ArgIncrement; // Move on to the next argument.
}
+ // Make sure the instruction takes 8n+4 bytes to make sure the start of the
+ // arguments and the arguments after the retaddr has been pushed are aligned.
+ if ((ArgOffset & 7) == 0)
+ ArgOffset += 4;
+
VarArgsFrameIndex = 0xAAAAAAA; // fastcc functions can't have varargs.
ReturnAddrIndex = 0; // No return address slot generated yet.
BytesToPopOnReturn = ArgOffset; // Callee pops all stack arguments.
@@ -602,6 +611,11 @@
break;
}
+ // Make sure the instruction takes 8n+4 bytes to make sure the start of the
+ // arguments and the arguments after the retaddr has been pushed are aligned.
+ if ((NumBytes & 7) == 0)
+ NumBytes += 4;
+
Chain = DAG.getNode(ISD::CALLSEQ_START, MVT::Other, Chain,
DAG.getConstant(NumBytes, getPointerTy()));
@@ -679,8 +693,14 @@
SDOperand TheCall = SDOperand(DAG.getCall(RetVals, Chain, Callee,
RegValuesToPass, isTailCall), 0);
Chain = TheCall.getValue(RetTyVT != MVT::isVoid);
+
+ // Make sure the instruction takes 8n+4 bytes to make sure the start of the
+ // arguments and the arguments after the retaddr has been pushed are aligned.
+ if ((ArgOffset & 7) == 0)
+ ArgOffset += 4;
+
Chain = DAG.getNode(ISD::CALLSEQ_END, MVT::Other, Chain,
- DAG.getConstant(NumBytes, getPointerTy()),
+ DAG.getConstant(ArgOffset, getPointerTy()),
// The callee pops the arguments off the stack.
DAG.getConstant(ArgOffset, getPointerTy()));
return std::make_pair(TheCall, Chain);
@@ -3781,7 +3801,7 @@
PrevI = BB->end();
BuildMI(*BB, PrevI, X86::ADJCALLSTACKUP, 2).addImm(Tmp1).addImm(Tmp2);
} else {
- BuildMI(*BB, PrevI, X86::ADJCALLSTACKUP, 2).addImm(Tmp1).addImm(Tmp2);
+ BuildMI(BB, X86::ADJCALLSTACKUP, 2).addImm(Tmp1).addImm(Tmp2);
}
return;
case ISD::MEMSET: {