[PEI] Add basic opt-remarks support

Add optimization remarks support to the PrologueEpilogueInserter. For
now, emit the stack size as an analysis remark, but more additions wrt
shrink-wrapping may be added.

https://reviews.llvm.org/D35645

llvm-svn: 308556

1 files changed, 13 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/PrologEpilogInserter.cpp b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
index b437b5c0b00..9361a2a8b0e 100644
--- a/llvm/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
@@ -25,6 +25,7 @@
 #include "llvm/CodeGen/MachineInstr.h"
 #include "llvm/CodeGen/MachineLoopInfo.h"
 #include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/CodeGen/MachineOptimizationRemarkEmitter.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/CodeGen/RegisterScavenging.h"
@@ -98,6 +99,9 @@ private:
   // FrameIndexVirtualScavenging is used.
   bool FrameIndexEliminationScavenging;
 
+  // Emit remarks.
+  MachineOptimizationRemarkEmitter *ORE = nullptr;
+
   void calculateCallFrameInfo(MachineFunction &Fn);
   void calculateSaveRestoreBlocks(MachineFunction &Fn);
   void doSpillCalleeSavedRegs(MachineFunction &MF);
@@ -122,6 +126,7 @@ INITIALIZE_PASS_BEGIN(PEI, DEBUG_TYPE, "Prologue/Epilogue Insertion", false,
 INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
 INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
 INITIALIZE_PASS_DEPENDENCY(StackProtector)
+INITIALIZE_PASS_DEPENDENCY(MachineOptimizationRemarkEmitterPass)
 INITIALIZE_PASS_END(PEI, DEBUG_TYPE,
                     "Prologue/Epilogue Insertion & Frame Finalization", false,
                     false)
@@ -138,6 +143,7 @@ void PEI::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.addPreserved<MachineLoopInfo>();
   AU.addPreserved<MachineDominatorTree>();
   AU.addRequired<StackProtector>();
+  AU.addRequired<MachineOptimizationRemarkEmitterPass>();
   MachineFunctionPass::getAnalysisUsage(AU);
 }
 
@@ -171,6 +177,7 @@ bool PEI::runOnMachineFunction(MachineFunction &Fn) {
   FrameIndexVirtualScavenging = TRI->requiresFrameIndexScavenging(Fn);
   FrameIndexEliminationScavenging = (RS && !FrameIndexVirtualScavenging) ||
     TRI->requiresFrameIndexReplacementScavenging(Fn);
+  ORE = &getAnalysis<MachineOptimizationRemarkEmitterPass>().getORE();
 
   // Calculate the MaxCallFrameSize and AdjustsStack variables for the
   // function's frame information. Also eliminates call frame pseudo
@@ -938,6 +945,12 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) {
   int64_t StackSize = Offset - LocalAreaOffset;
   MFI.setStackSize(StackSize);
   NumBytesStackSpace += StackSize;
+
+  MachineOptimizationRemarkAnalysis R(
+      DEBUG_TYPE, "StackSize", Fn.getFunction()->getSubprogram(), &Fn.front());
+  R << ore::NV("NumStackBytes", static_cast<unsigned>(StackSize))
+    << " stack bytes in function";
+  ORE->emit(R);
 }
 
 /// insertPrologEpilogCode - Scan the function for modified callee saved