[PGO] Better handling of profile hash mismatch

We currently assume profile hash conflicts will be caught by an upfront
check and we assert for the cases that escape the check. The assumption
is not always true as there are chances of conflict. This patch prints
a warning and skips annotating the function for the escaped cases,.

Differential Revision: https://reviews.llvm.org/D60154

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@358225 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Instrumentation/PGOInstrumentation.cpp b/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
index 99377b8a6cdc033d82b8a27e4c4ba8bfb1b8f987..b1c7687e19f001e20ffc8cb86411aec723db774e 100644 (file)
--- a/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ b/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -1006,8 +1006,8 @@ private:
   // Is to use the context sensitive profile.
   bool IsCS;
 
-  // Find the Instrumented BB and set the value.
-  void setInstrumentedCounts(const std::vector<uint64_t> &CountFromProfile);
+  // Find the Instrumented BB and set the value. Return false on error.
+  bool setInstrumentedCounts(const std::vector<uint64_t> &CountFromProfile);
 
   // Set the edge counter value for the unknown edge -- there should be only
   // one unknown edge.
@@ -1036,10 +1036,14 @@ private:
 } // end anonymous namespace
 
 // Visit all the edges and assign the count value for the instrumented
-// edges and the BB.
-void PGOUseFunc::setInstrumentedCounts(
+// edges and the BB. Return false on error.
+bool PGOUseFunc::setInstrumentedCounts(
     const std::vector<uint64_t> &CountFromProfile) {
-  assert(FuncInfo.getNumCounters() == CountFromProfile.size());
+  // The number of counters here should match the number of counters
+  // in profile. Return if they mismatch.
+  if (FuncInfo.getNumCounters() != CountFromProfile.size()) {
+    return false;
+  }
   // Use a worklist as we will update the vector during the iteration.
   std::vector<PGOUseEdge *> WorkList;
   for (auto &E : FuncInfo.MST.AllEdges)
@@ -1071,6 +1075,7 @@ void PGOUseFunc::setInstrumentedCounts(
   }
   ProfileCountSize = CountFromProfile.size();
   CountPosition = I;
+  return true;
 }
 
 // Set the count value for the unknown edge. There should be one and only one
@@ -1146,7 +1151,16 @@ bool PGOUseFunc::readCounters(IndexedInstrProfReader *PGOReader, bool &AllZeros)
   getBBInfo(nullptr).UnknownCountOutEdge = 2;
   getBBInfo(nullptr).UnknownCountInEdge = 2;
 
-  setInstrumentedCounts(CountFromProfile);
+  if (!setInstrumentedCounts(CountFromProfile)) {
+    LLVM_DEBUG(
+        dbgs() << "Inconsistent number of counts, skipping this function");
+    Ctx.diagnose(DiagnosticInfoPGOProfile(
+        M->getName().data(),
+        Twine("Inconsistent number of counts in ") + F.getName().str()
+        + Twine(": the profile may be stale or there is a function name collision."),
+        DS_Warning));
+    return false;
+  }
   ProgramMaxCount = PGOReader->getMaximumFunctionCount(IsCS);
   return true;
 }

diff --git a/test/Transforms/PGOProfile/Inputs/select_hash_conflict.proftext b/test/Transforms/PGOProfile/Inputs/select_hash_conflict.proftext
new file mode 100644 (file)
index 0000000..ccc3b80
--- /dev/null
+++ b/test/Transforms/PGOProfile/Inputs/select_hash_conflict.proftext
@@ -0,0 +1,10 @@
+# IR level Instrumentation Flag
+:ir
+foo
+# Func Hash:
+12884901887
+# Num Counters:
+1
+# Counter Values:
+1
+

diff --git a/test/Transforms/PGOProfile/select_hash_conflict.ll b/test/Transforms/PGOProfile/select_hash_conflict.ll
new file mode 100644 (file)
index 0000000..e7c3cdb
--- /dev/null
+++ b/test/Transforms/PGOProfile/select_hash_conflict.ll
@@ -0,0 +1,97 @@
+; RUN: llvm-profdata merge %S/Inputs/select_hash_conflict.proftext -o %t.profdata
+; RUN: opt < %s -pgo-instr-use -pgo-test-profile-file=%t.profdata -pgo-instr-select=true -S | FileCheck %s
+; RUN: opt < %s -passes=pgo-instr-use -pgo-test-profile-file=%t.profdata -pgo-instr-select=true -S | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@a = common dso_local local_unnamed_addr global [16 x i32] zeroinitializer, align 16
+@c0 = common dso_local local_unnamed_addr global i8 0, align 1
+@c1 = common dso_local local_unnamed_addr global i8 0, align 1
+@c2 = common dso_local local_unnamed_addr global i8 0, align 1
+@c3 = common dso_local local_unnamed_addr global i8 0, align 1
+@c4 = common dso_local local_unnamed_addr global i8 0, align 1
+@c5 = common dso_local local_unnamed_addr global i8 0, align 1
+@c6 = common dso_local local_unnamed_addr global i8 0, align 1
+@c7 = common dso_local local_unnamed_addr global i8 0, align 1
+@c8 = common dso_local local_unnamed_addr global i8 0, align 1
+@c9 = common dso_local local_unnamed_addr global i8 0, align 1
+@c10 = common dso_local local_unnamed_addr global i8 0, align 1
+@c11 = common dso_local local_unnamed_addr global i8 0, align 1
+@c12 = common dso_local local_unnamed_addr global i8 0, align 1
+@c13 = common dso_local local_unnamed_addr global i8 0, align 1
+@c14 = common dso_local local_unnamed_addr global i8 0, align 1
+@c15 = common dso_local local_unnamed_addr global i8 0, align 1
+
+define i32 @foo(i32 %n) {
+entry:
+  %0 = load i8, i8* @c0, align 1
+  %tobool = icmp eq i8 %0, 0
+  %cond = select i1 %tobool, i32 2, i32 1
+  store i32 %cond, i32* getelementptr inbounds ([16 x i32], [16 x i32]* @a, i64 0, i64 0), align 16
+  %1 = load i8, i8* @c1, align 1
+  %tobool2 = icmp eq i8 %1, 0
+  %cond3 = select i1 %tobool2, i32 2, i32 1
+  store i32 %cond3, i32* getelementptr inbounds ([16 x i32], [16 x i32]* @a, i64 0, i64 1), align 4
+  %2 = load i8, i8* @c2, align 1
+  %tobool5 = icmp eq i8 %2, 0
+  %cond6 = select i1 %tobool5, i32 2, i32 1
+  store i32 %cond6, i32* getelementptr inbounds ([16 x i32], [16 x i32]* @a, i64 0, i64 2), align 8
+  %3 = load i8, i8* @c3, align 1
+  %tobool8 = icmp eq i8 %3, 0
+  %cond9 = select i1 %tobool8, i32 2, i32 1
+  store i32 %cond9, i32* getelementptr inbounds ([16 x i32], [16 x i32]* @a, i64 0, i64 3), align 4
+  %4 = load i8, i8* @c4, align 1
+  %tobool11 = icmp eq i8 %4, 0
+  %cond12 = select i1 %tobool11, i32 2, i32 1
+  store i32 %cond12, i32* getelementptr inbounds ([16 x i32], [16 x i32]* @a, i64 0, i64 4), align 16
+  %5 = load i8, i8* @c5, align 1
+  %tobool14 = icmp eq i8 %5, 0
+  %cond15 = select i1 %tobool14, i32 2, i32 1
+  store i32 %cond15, i32* getelementptr inbounds ([16 x i32], [16 x i32]* @a, i64 0, i64 5), align 4
+  %6 = load i8, i8* @c6, align 1
+  %tobool17 = icmp eq i8 %6, 0
+  %cond18 = select i1 %tobool17, i32 2, i32 1
+  store i32 %cond18, i32* getelementptr inbounds ([16 x i32], [16 x i32]* @a, i64 0, i64 6), align 8
+  %7 = load i8, i8* @c7, align 1
+  %tobool20 = icmp eq i8 %7, 0
+  %cond21 = select i1 %tobool20, i32 2, i32 1
+  store i32 %cond21, i32* getelementptr inbounds ([16 x i32], [16 x i32]* @a, i64 0, i64 7), align 4
+  %8 = load i8, i8* @c8, align 1
+  %tobool23 = icmp eq i8 %8, 0
+  %cond24 = select i1 %tobool23, i32 2, i32 1
+  store i32 %cond24, i32* getelementptr inbounds ([16 x i32], [16 x i32]* @a, i64 0, i64 8), align 16
+  %9 = load i8, i8* @c9, align 1
+  %tobool26 = icmp eq i8 %9, 0
+  %cond27 = select i1 %tobool26, i32 2, i32 1
+  store i32 %cond27, i32* getelementptr inbounds ([16 x i32], [16 x i32]* @a, i64 0, i64 9), align 4
+  %10 = load i8, i8* @c10, align 1
+  %tobool29 = icmp eq i8 %10, 0
+  %cond30 = select i1 %tobool29, i32 2, i32 1
+  store i32 %cond30, i32* getelementptr inbounds ([16 x i32], [16 x i32]* @a, i64 0, i64 10), align 8
+  %11 = load i8, i8* @c11, align 1
+  %tobool32 = icmp eq i8 %11, 0
+  %cond33 = select i1 %tobool32, i32 2, i32 1
+  store i32 %cond33, i32* getelementptr inbounds ([16 x i32], [16 x i32]* @a, i64 0, i64 11), align 4
+  %12 = load i8, i8* @c12, align 1
+  %tobool35 = icmp eq i8 %12, 0
+  %cond36 = select i1 %tobool35, i32 2, i32 1
+  store i32 %cond36, i32* getelementptr inbounds ([16 x i32], [16 x i32]* @a, i64 0, i64 12), align 16
+  %13 = load i8, i8* @c13, align 1
+  %tobool38 = icmp eq i8 %13, 0
+  %cond39 = select i1 %tobool38, i32 2, i32 1
+  store i32 %cond39, i32* getelementptr inbounds ([16 x i32], [16 x i32]* @a, i64 0, i64 13), align 4
+  %14 = load i8, i8* @c14, align 1
+  %tobool41 = icmp eq i8 %14, 0
+  %cond42 = select i1 %tobool41, i32 2, i32 1
+  store i32 %cond42, i32* getelementptr inbounds ([16 x i32], [16 x i32]* @a, i64 0, i64 14), align 8
+  %15 = load i8, i8* @c15, align 1
+  %tobool44 = icmp eq i8 %15, 0
+  %cond45 = select i1 %tobool44, i32 2, i32 1
+  store i32 %cond45, i32* getelementptr inbounds ([16 x i32], [16 x i32]* @a, i64 0, i64 15), align 4
+  ret i32 %n
+}
+; CHECK-LABEL: define i32 @foo(i32 %n)
+; We should skip the profile.
+; CHECK-NOT: %{{.*}} = select i1 %{{.*}}, i32 2, i32 1, !prof
+