ARM / x86_64 varargs: Don't save regparms in prologue without va_start

There's no need to do this if the user doesn't call va_start. In the
future, we're going to have thunks that forward these register
parameters with musttail calls, and they won't need these spills for
handling va_start.

Most of the test suite changes are adding va_start calls to existing
tests to keep things working.

llvm-svn: 216294

1 files changed, 2 insertions, 2 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index 42c8f202e0f..f5355833a34 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -3080,7 +3080,7 @@ ARMTargetLowering::LowerFormalArguments(SDValue Chain,
   }
   CCInfo.rewindByValRegsInfo();
   lastInsIndex = -1;
-  if (isVarArg) {
+  if (isVarArg && MFI->hasVAStart()) {
     unsigned ExtraArgRegsSize;
     unsigned ExtraArgRegsSaveSize;
     computeRegArea(CCInfo, MF, CCInfo.getInRegsParamsCount(), 0,
@@ -3222,7 +3222,7 @@ ARMTargetLowering::LowerFormalArguments(SDValue Chain,
   }
 
   // varargs
-  if (isVarArg)
+  if (isVarArg && MFI->hasVAStart())
     VarArgStyleRegisters(CCInfo, DAG, dl, Chain,
                          CCInfo.getNextStackOffset(),
                          TotalArgRegsSaveSize);