[PowerPC] Add handling for ColdCC calling convention and a pass to mark

candidates with coldcc attribute.

This patch adds support for the coldcc calling convention for Power.
This changes the set of non-volatile registers. It includes a pass to stress
test the implementation by marking all static directly called functions with
the coldcc attribute through the option -enable-coldcc-stress-test. It also
includes an option, -ppc-enable-coldcc, to add the coldcc attribute to
functions which are cold at all call sites based on BlockFrequencyInfo when
the containing function does not call any non cold functions.

Differential Revision: https://reviews.llvm.org/D38413

llvm-svn: 322721

1 files changed, 14 insertions, 3 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 3c09ab8d755..34f7fc99f58 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -4939,7 +4939,11 @@ SDValue PPCTargetLowering::LowerCallResult(
   SmallVector<CCValAssign, 16> RVLocs;
   CCState CCRetInfo(CallConv, isVarArg, DAG.getMachineFunction(), RVLocs,
                     *DAG.getContext());
-  CCRetInfo.AnalyzeCallResult(Ins, RetCC_PPC);
+
+  CCRetInfo.AnalyzeCallResult(
+      Ins, (Subtarget.isSVR4ABI() && CallConv == CallingConv::Cold)
+               ? RetCC_PPC_Cold
+               : RetCC_PPC);
 
   // Copy all of the result registers out of their specified physreg.
   for (unsigned i = 0, e = RVLocs.size(); i != e; ++i) {
@@ -5159,6 +5163,7 @@ SDValue PPCTargetLowering::LowerCall_32SVR4(
   // of the 32-bit SVR4 ABI stack frame layout.
 
   assert((CallConv == CallingConv::C ||
+          CallConv == CallingConv::Cold ||
           CallConv == CallingConv::Fast) && "Unknown calling convention!");
 
   unsigned PtrByteSize = 4;
@@ -6420,7 +6425,10 @@ PPCTargetLowering::CanLowerReturn(CallingConv::ID CallConv,
                                   LLVMContext &Context) const {
   SmallVector<CCValAssign, 16> RVLocs;
   CCState CCInfo(CallConv, isVarArg, MF, RVLocs, Context);
-  return CCInfo.CheckReturn(Outs, RetCC_PPC);
+  return CCInfo.CheckReturn(
+      Outs, (Subtarget.isSVR4ABI() && CallConv == CallingConv::Cold)
+                ? RetCC_PPC_Cold
+                : RetCC_PPC);
 }
 
 SDValue
@@ -6432,7 +6440,10 @@ PPCTargetLowering::LowerReturn(SDValue Chain, CallingConv::ID CallConv,
   SmallVector<CCValAssign, 16> RVLocs;
   CCState CCInfo(CallConv, isVarArg, DAG.getMachineFunction(), RVLocs,
                  *DAG.getContext());
-  CCInfo.AnalyzeReturn(Outs, RetCC_PPC);
+  CCInfo.AnalyzeReturn(Outs,
+                       (Subtarget.isSVR4ABI() && CallConv == CallingConv::Cold)
+                           ? RetCC_PPC_Cold
+                           : RetCC_PPC);
 
   SDValue Flag;
   SmallVector<SDValue, 4> RetOps(1, Chain);