[llvm-dwarfdump][Statistics] Don't count coverage less than 1% as 0%

Summary:
This is a follow up for D70548.
Currently, variables with debug info coverage between 0% and 1% are put into
zero-bucket. D70548 changed the way statistics calculate a variable's coverage:
we began to use enclosing scope rather than a possible variable life range.
Thus more variables might be moved to zero-bucket despite they have some debug
info coverage.
The patch is to distinguish between a variable that has location info but
it's significantly less than its enclosing scope and a variable that doesn't
have it at all.

Reviewers: djtodoro, aprantl, dblaikie, avl

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D71070

1 files changed, 10 insertions, 12 deletions

diff --git a/llvm/tools/llvm-dwarfdump/Statistics.cpp b/llvm/tools/llvm-dwarfdump/Statistics.cpp
index 2d0f30476e3..5bef4d5148c 100644
--- a/llvm/tools/llvm-dwarfdump/Statistics.cpp
+++ b/llvm/tools/llvm-dwarfdump/Statistics.cpp
@@ -138,18 +138,16 @@ static void collectLocStats(uint64_t BytesCovered, uint64_t BytesInScope,
                             std::vector<unsigned> &VarLocStats, bool IsParam,
                             bool IsLocalVar) {
   auto getCoverageBucket = [BytesCovered, BytesInScope]() -> unsigned {
-    unsigned LocBucket = 100 * (double)BytesCovered / BytesInScope;
-    if (LocBucket == 0) {
-      // No debug location at all for the variable.
+    // No debug location at all for the variable.
+    if (BytesCovered == 0)
       return 0;
-    } else if (LocBucket == 100 || BytesCovered > BytesInScope) {
-      // Fully covered variable within its scope.
+    // Fully covered variable within its scope.
+    if (BytesCovered >= BytesInScope)
       return NumOfCoverageCategories - 1;
-    } else {
-      // Get covered range (e.g. 20%-29%).
-      LocBucket /= 10;
-      return LocBucket + 1;
-    }
+    // Get covered range (e.g. 20%-29%).
+    unsigned LocBucket = 100 * (double)BytesCovered / BytesInScope;
+    LocBucket /= 10;
+    return LocBucket + 1;
   };
 
   unsigned CoverageBucket = getCoverageBucket();
@@ -430,9 +428,9 @@ static void printLocationStats(raw_ostream &OS,
      << LocationStats[0];
   LLVM_DEBUG(llvm::dbgs() << Key << " with 0% of its scope covered: "
                           << LocationStats[0] << '\n');
-  OS << ",\"" << Key << " with [1%,10%) of its scope covered\":"
+  OS << ",\"" << Key << " with (0%,10%) of its scope covered\":"
      << LocationStats[1];
-  LLVM_DEBUG(llvm::dbgs() << Key << " with [1%,10%) of its scope covered: "
+  LLVM_DEBUG(llvm::dbgs() << Key << " with (0%,10%) of its scope covered: "
                           << LocationStats[1] << '\n');
   for (unsigned i = 2; i < NumOfCoverageCategories - 1; ++i) {
     OS << ",\"" << Key << " with [" << (i - 1) * 10 << "%," << i * 10