SamplePGO - Add line offset and discriminator information to sample reports.

While debugging some sampling coverage problems, I found this useful:
When applying samples from a profile, it helps to also know what line
offset and discriminator the sample belongs to. This makes it easy to
correlate against the input profile.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@253670 91177308-0d34-0410-b5e6-96231b3b80d8

Author: Diego Novillo

lib/Transforms/IPO/SampleProfile.cpp

@@ -344,9 +344,11 @@ SampleProfileLoader::getInstWeight(const Instruction &Inst) const {
     if (FirstMark) {
       const Function *F = Inst.getParent()->getParent();
       LLVMContext &Ctx = F->getContext();
-      emitOptimizationRemark(Ctx, DEBUG_TYPE, *F, DLoc,
-                             Twine("Applied ") + Twine(*R) +
-                                 " samples from profile");
+      emitOptimizationRemark(
+          Ctx, DEBUG_TYPE, *F, DLoc,
+          Twine("Applied ") + Twine(*R) + " samples from profile (offset: " +
+              Twine(LineOffset) +
+              ((Discriminator) ? Twine(".") + Twine(Discriminator) : "") + ")");
     }
     DEBUG(dbgs() << "    " << Lineno << "." << DIL->getDiscriminator() << ":"
                  << Inst << " (line offset: " << Lineno - HeaderLineno << "."

test/Transforms/SampleProfile/inline-coverage.ll

@@ -16,10 +16,10 @@
 ;    12    }
 ;
 ; CHECK: remark: coverage.cc:10:12: inlined hot callee '_Z3fool' with 172746 samples into 'main'
-; CHECK: remark: coverage.cc:9:19: Applied 23478 samples from profile
-; CHECK: remark: coverage.cc:10:16: Applied 23478 samples from profile
-; CHECK: remark: coverage.cc:4:10: Applied 31878 samples from profile
-; CHECK: remark: coverage.cc:11:10: Applied 0 samples from profile
+; CHECK: remark: coverage.cc:9:19: Applied 23478 samples from profile (offset: 2.1)
+; CHECK: remark: coverage.cc:10:16: Applied 23478 samples from profile (offset: 3)
+; CHECK: remark: coverage.cc:4:10: Applied 31878 samples from profile (offset: 1)
+; CHECK: remark: coverage.cc:11:10: Applied 0 samples from profile (offset: 4)
 ; CHECK: remark: coverage.cc:10:16: most popular destination for conditional branches at coverage.cc:9:3
 ;
 ; There is one sample record with 0 samples at offset 4 in main() that we never