From 2d9bb65b3dee3d84a523f043b6059bce2a4a1032 Mon Sep 17 00:00:00 2001 From: Reid Kleckner Date: Fri, 22 Aug 2014 21:59:26 +0000 Subject: 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 --- llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp') diff --git a/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp index 1c85248eb84..c9da6fd83ee 100644 --- a/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp @@ -138,6 +138,14 @@ void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf, } } + // Look for calls to the @llvm.va_start intrinsic. We can omit some + // prologue boilerplate for variadic functions that don't examine their + // arguments. + if (const auto *II = dyn_cast(I)) { + if (II->getIntrinsicID() == Intrinsic::vastart) + MF->getFrameInfo()->setHasVAStart(true); + } + // Mark values used outside their block as exported, by allocating // a virtual register for them. if (isUsedOutsideOfDefiningBlock(I)) -- cgit v1.2.3