[misexpect] Support missing-annotations diagnostics from frontend profile data

clang/test/Profile/missing-annotations-branch.c

@@ -0,0 +1,62 @@
+// RUN: rm -rf %t && mkdir -p %t
+// RUN: split-file %s %t
+
+/// Test that missing-annotations detects branches that are hot, but not annotated.
+// RUN: llvm-profdata merge %t/a.proftext -o %t/profdata
+// RUN: %clang_cc1 %t/a.c -O2 -o - -emit-llvm -fprofile-instrument-use-path=%t/profdata -verify -mllvm -pgo-missing-annotations -Rpass=missing-annotations  -fdiagnostics-misexpect-tolerance=10
+
+/// Test that we don't report any diagnostics, if the threshold isn't exceeded.
+// RUN: %clang_cc1 %t/a.c -O2 -o - -emit-llvm -fprofile-instrument-use-path=%t/profdata -mllvm -pgo-missing-annotations -Rpass=missing-annotations  2>&1 | FileCheck -implicit-check-not=remark %s
+
+//--- a.c
+// foo-no-diagnostics
+#define UNLIKELY(x) __builtin_expect(!!(x), 0)
+
+int foo(int);
+int baz(int);
+int buzz(void);
+
+const int inner_loop = 100;
+const int outer_loop = 2000;
+
+int bar(void) { //  imprecise-remark-re {{Extremely hot condition. Consider adding llvm.expect intrinsic{{.*}}}}
+  int a = buzz();
+  int x = 0;
+  if (a % (outer_loop * inner_loop) == 0) { // expected-remark {{Extremely hot condition. Consider adding llvm.expect intrinsic}}
+    x = baz(a);
+  } else {
+    x = foo(50);
+  }
+  return x;
+}
+
+int fizz(void) {
+  int a = buzz();
+  int x = 0;
+  if ((a % (outer_loop * inner_loop) == 0)) { // expected-remark-re {{Extremely hot condition. Consider adding llvm.expect intrinsic{{.*}}}}}
+    x = baz(a);
+  } else {
+    x = foo(50);
+  }
+  return x;
+}
+
+//--- a.proftext
+bar
+# Func Hash:
+11262309464
+# Num Counters:
+2
+# Counter Values:
+1901
+99
+
+fizz
+# Func Hash:
+11262309464
+# Num Counters:
+2
+# Counter Values:
+1901
+99
+

clang/test/Profile/missing-annotations-switch.c

@@ -0,0 +1,64 @@
+// RUN: rm -rf %t && mkdir -p %t
+// RUN: split-file %s %t
+
+/// Test that missing-annotations detects switch conditions that are hot, but not annotated.
+// RUN: llvm-profdata merge %t/a.proftext -o %t/profdata
+// RUN: %clang_cc1 %t/a.c -O2 -o - -emit-llvm -fprofile-instrument-use-path=%t/profdata -verify -mllvm -pgo-missing-annotations -Rpass=missing-annotations -fdiagnostics-misexpect-tolerance=10
+
+/// Test that we don't report any diagnostics, if the threshold isn't exceeded.
+// RUN: %clang_cc1 %t/a.c -O2 -o - -emit-llvm -fprofile-instrument-use-path=%t/profdata -mllvm -pgo-missing-annotations -Rpass=missing-annotations  2>&1 | FileCheck -implicit-check-not=remark %s
+
+//--- a.c
+#define inner_loop 1000
+#define outer_loop 20
+#define arry_size 25
+
+int arry[arry_size] = {0};
+
+int rand(void);
+int sum(int *buff, int size);
+int random_sample(int *buff, int size);
+
+int main(void) {
+  int val = 0;
+
+  int j, k;
+  for (j = 0; j < outer_loop; ++j) {
+    for (k = 0; k < inner_loop; ++k) {
+      unsigned condition = rand() % 10000;
+      switch (condition) { // expected-remark {{Extremely hot condition. Consider adding llvm.expect intrinsic}}
+
+      case 0:
+        val += sum(arry, arry_size);
+        break;
+      case 1:
+      case 2:
+      case 3:
+        break;
+      default:
+        val += random_sample(arry, arry_size);
+        break;
+      } // end switch
+    }   // end inner_loop
+  }     // end outer_loop
+
+  return val;
+}
+
+//--- a.proftext
+main
+# Func Hash:
+872687477373597607
+# Num Counters:
+9
+# Counter Values:
+2
+9
+2
+2
+3
+3
+1
+999
+18001
+

llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp

@@ -369,9 +369,21 @@ static bool lowerExpectIntrinsic(Function &F) {
     if (BranchInst *BI = dyn_cast<BranchInst>(BB.getTerminator())) {
       if (handleBranchExpect(*BI))
         ExpectIntrinsicsHandled++;
+      else {
+        SmallVector<uint32_t> Weights;
+        if (extractBranchWeights(*BI, Weights))
+          misexpect::checkMissingAnnotations(*BI, Weights,
+                                             /*IsFrontendInstr=*/true);
+      }
     } else if (SwitchInst *SI = dyn_cast<SwitchInst>(BB.getTerminator())) {
       if (handleSwitchExpect(*SI))
         ExpectIntrinsicsHandled++;
+      else {
+        SmallVector<uint32_t> Weights;
+        if (extractBranchWeights(*SI, Weights))
+          misexpect::checkMissingAnnotations(*SI, Weights,
+                                             /*isFrontend=*/true);
+      }
     }
 
     // Remove llvm.expect intrinsics. Iterate backwards in order
@@ -383,6 +395,12 @@ static bool lowerExpectIntrinsic(Function &F) {
         if (SelectInst *SI = dyn_cast<SelectInst>(&Inst)) {
           if (handleBrSelExpect(*SI))
             ExpectIntrinsicsHandled++;
+          else {
+            SmallVector<uint32_t> Weights;
+            if (extractBranchWeights(*SI, Weights))
+              misexpect::checkMissingAnnotations(*SI, Weights,
+                                                 /*isFrontend=*/true);
+          }
         }
         continue;
       }

llvm/lib/Transforms/Utils/MisExpect.cpp

@@ -302,8 +302,7 @@ void checkMissingAnnotations(Instruction &I,
     return;
 
   if (IsFrontendInstr) {
-    // TODO: Frontend checking will have to be thought through, since we need
-    // to do the check on branches that don't have expect intrinsics
+    verifyMissingAnnotations(I, ExistingWeights);
   } else {
     SmallVector<uint32_t> ExpectedWeights;
     if (extractBranchWeights(I, ExpectedWeights))