[Flang][Driver] Add support for backend passes in R_Group

Previously, R_Group options only reported middle-end passes.
This patch allows backend passes to be reported as well.

Depends on D158174. That patch adds backend support to R_Group
options.

Reviewed By: awarzynski

Differential Revision: https://reviews.llvm.org/D159260

flang/lib/Frontend/FrontendActions.cpp

@@ -48,6 +48,7 @@
 #include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/Bitcode/BitcodeWriterPass.h"
+#include "llvm/CodeGen/MachineOptimizationRemarkEmitter.h"
 #include "llvm/IR/LLVMRemarkStreamer.h"
 #include "llvm/IR/LegacyPassManager.h"
 #include "llvm/IR/Verifier.h"
@@ -1014,6 +1015,18 @@ public:
       optimizationRemarkHandler(
           llvm::cast<llvm::OptimizationRemarkAnalysis>(di));
       break;
+    case llvm::DK_MachineOptimizationRemark:
+      optimizationRemarkHandler(
+          llvm::cast<llvm::MachineOptimizationRemark>(di));
+      break;
+    case llvm::DK_MachineOptimizationRemarkMissed:
+      optimizationRemarkHandler(
+          llvm::cast<llvm::MachineOptimizationRemarkMissed>(di));
+      break;
+    case llvm::DK_MachineOptimizationRemarkAnalysis:
+      optimizationRemarkHandler(
+          llvm::cast<llvm::MachineOptimizationRemarkAnalysis>(di));
+      break;
     default:
       break;
     }

flang/test/Driver/optimization-remark-backend.f90

@@ -0,0 +1,23 @@
+! This file tests backend passes emitted by the -Rpass family of flags
+! loop-delete isn't enabled at O0 so we use at least O1
+
+! DEFINE: %{output} = -S -o /dev/null 2>&1
+
+! Check full -Rpass-missed message is emitted
+! RUN: %flang %s -O1 -Rpass-missed %{output} 2>&1 | FileCheck %s --check-prefix=MISSED
+
+! Check full -Rpass-analysis message is emitted
+! RUN: %flang %s -O1 -Rpass-analysis %{output} 2>&1 | FileCheck %s --check-prefix=ANALYSIS
+
+! MISSED:   remark: {{[0-9]+}} virtual registers copies {{.*}} total copies cost generated in function
+! ANALYSIS: remark: BasicBlock:
+
+program forttest
+    implicit none
+    integer :: n
+
+    do n = 1,2
+        print *, ""
+    end do
+
+end program forttest