Improve --report_progress_every flag (llvm#64)

Currently, the --report_progress_every flag, even with the default
value, will always report progress on the first block. This is not the
intended behavior, as no output should be given with the default value.
This patch fixes that behavior and also adds a test to ensure that the
flag functions as intended in the default value case and in the
value-provided case.

Not really super critical to functionality, but a little bit annoying to
have this.

Author: boomanaiden154

gematria/datasets/convert_bhive_to_llvm_exegesis_input.cc

@@ -340,7 +340,7 @@ int main(int argc, char* argv[]) {
       }
     }
 
-    if (file_counter % report_progress_every == 0)
+    if (file_counter != 0 && file_counter % report_progress_every == 0)
       std::cerr << "Finished annotating block #" << file_counter << ".\n";
 
     file_counter++;

gematria/datasets/tests/report_progress.test

@@ -0,0 +1,22 @@
+; Test that the --report_progress_every reports progress at the expected
+; intervals.
+
+; RUN: split-file %s %t
+; RUN: mkdir %t.asmdir
+; RUN: %convert_bhive_to_llvm_exegesis_input --asm_output_dir=%t.asmdir --bhive_csv=%t/test.csv --report_progress_every=2 2>&1 | FileCheck %s
+
+; CHECK: Finished annotating block #2.
+; CHECK: Finished annotating block #4.
+
+; Test that --report_progress_every doesn't output anything with the default
+; value.
+; RUN: %convert_bhive_to_llvm_exegesis_input --asm_output_dir=%t.asmdir --bhive_csv=%t/test.csv 2>&1 | FileCheck %s --check-prefix=DEFAULT-VALUE
+
+; DEFAULT-VALUE-NOT: Finished annotating block
+
+;--- test.csv
+4183ff0119c083e00885c98945c4b8010000000f4fc139c2,298.000000
+4889de4889c24c89ff,93.000000
+48895d1844886520488945004889e84883c4085b5d415c415d,335.000000
+418b4424084d8b3424498d2cc64939ee,98.000000
+85c044897c2460,98.000000