[llvm-profdata] Change instr prof counter overflow to saturate rather than discard

Summary: This changes overflow handling during instrumentation profile merge. Rathar than throwing away records that would result in counter overflow, merged counts are instead clamped to the maximum representable value. A warning about counter overflow is still surfaced to the user as before.

Reviewers: dnovillo, davidxl, silvas

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D14893

llvm-svn: 254525

1 files changed, 4 insertions, 1 deletions

diff --git a/llvm/unittests/ProfileData/InstrProfTest.cpp b/llvm/unittests/ProfileData/InstrProfTest.cpp
index 2f3adb65a0e..635a5431a51 100644
--- a/llvm/unittests/ProfileData/InstrProfTest.cpp
+++ b/llvm/unittests/ProfileData/InstrProfTest.cpp
@@ -354,7 +354,7 @@ TEST_F(InstrProfTest, get_icall_data_merge1_saturation) {
   const uint64_t Max = std::numeric_limits<uint64_t>::max();
 
   InstrProfRecord Record1("caller", 0x1234, {1});
-  InstrProfRecord Record2("caller", 0x1234, {1});
+  InstrProfRecord Record2("caller", 0x1234, {Max});
   InstrProfRecord Record3("callee1", 0x1235, {3, 4});
 
   Record1.reserveSites(IPVK_IndirectCallTarget, 1);
@@ -375,6 +375,9 @@ TEST_F(InstrProfTest, get_icall_data_merge1_saturation) {
   // Verify saturation of counts.
   ErrorOr<InstrProfRecord> R = Reader->getInstrProfRecord("caller", 0x1234);
   ASSERT_TRUE(NoError(R.getError()));
+
+  ASSERT_EQ(Max, R.get().Counts[0]);
+
   ASSERT_EQ(1U, R.get().getNumValueSites(IPVK_IndirectCallTarget));
   std::unique_ptr<InstrProfValueData[]> VD =
           R.get().getValueForSite(IPVK_IndirectCallTarget, 0);