Add support for optimization reports.

Summary:
This patch adds backend support for -Rpass=, which indicates the name
of the optimization pass that should emit remarks stating when it
made a transformation to the code.

Pass names are taken from their DEBUG_NAME definitions.

When emitting an optimization report diagnostic, the lack of debug
information causes the diagnostic to use "<unknown>:0:0" as the
location string.

This is the back end counterpart for

http://llvm-reviews.chandlerc.com/D3226

Reviewers: qcolombet

CC: llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D3227

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205774 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/IPO/Inliner.cpp

@@ -21,6 +21,7 @@
 #include "llvm/Analysis/InlineCost.h"
 #include "llvm/IR/CallSite.h"
 #include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/Module.h"
@@ -522,7 +523,12 @@ bool Inliner::runOnSCC(CallGraphSCC &SCC) {
                                   InlineHistoryID, InsertLifetime, DL))
           continue;
         ++NumInlined;
-        
+
+        // Report the inline decision.
+        Caller->getContext().emitOptimizationRemark(
+            DEBUG_TYPE, *Caller, CS.getInstruction()->getDebugLoc(),
+            Twine(Callee->getName() + " inlined into " + Caller->getName()));
+
         // If inlining this function gave us any new call sites, throw them
         // onto our worklist to process.  They are useful inline candidates.
         if (!InlineInfo.InlinedCalls.empty()) {