[Coverage] Support for C++17 switch initializers

[vsk]

Summary

Generate coverage mappings for <init> in switch (<init>; <cond>).

[arphaman]

I'm unsure about whether or not the CodeGenPGO change in this patch deserves more testing.

It wouldn't harm to add a test for CodeGenPGO as well. A good test that you can as a starting point for the new one is test/Profile/cxx-rangefor.cpp. A single PGOGEN check for a PGO counter generated from a subexpression in a switch initializer should be sufficient.

lib/CodeGen/CoverageMappingGen.cpp

818

I noticed that you added a newline here, wouldn't it be better to have it after extendRegion(S) so that the Visit calls are grouped together?

[vsk]

Per @arphaman's comments:

• Add a CodeGenPGO test which checks whether counters can be created for statements inside of switch initializers.
• Group calls to 'Visit' together.

[ikudrin]

LGTM.

lib/CodeGen/CodeGenPGO.cpp

void VisitObjCForCollectionStmt(const ObjCForCollectionStmt *S) {
 
     setCount(BC.BreakCount + ParentCount + BackedgeCount + BC.ContinueCount -
              BodyCount);
     RecordNextStmtCount = true;
   }
 
   void VisitSwitchStmt(const SwitchStmt *S) {
     RecordStmtCount(S);
+    if (S->getInit())
+      Visit(S->getInit());
     Visit(S->getCond());
     CurrentCount = 0;
     BreakContinueStack.push_back(BreakContinue());
     Visit(S->getBody());
     // If the switch is inside a loop, add the continue counts.
     BreakContinue BC = BreakContinueStack.pop_back_val();
     if (!BreakContinueStack.empty())
       BreakContinueStack.back().ContinueCount += BC.ContinueCount;

lib/CodeGen/CoverageMappingGen.cpp

     Counter OutCount =
         addCounters(BC.BreakCount, subtractCounters(LoopCount, BodyCount));
     if (OutCount != ParentCount)
       pushRegion(OutCount);
   }
 
   void VisitSwitchStmt(const SwitchStmt *S) {
     extendRegion(S);
+    if (S->getInit())
+      Visit(S->getInit());
+
     Visit(S->getCond());
 
     BreakContinueStack.push_back(BreakContinue());
 
     const Stmt *Body = S->getBody();
     extendRegion(Body);
     if (const auto *CS = dyn_cast<CompoundStmt>(Body)) {
       if (!CS->body_empty()) {

test/CoverageMapping/switch.cpp

-// RUN: %clang_cc1 -fprofile-instrument=clang -fcoverage-mapping -dump-coverage-mapping -emit-llvm-only -main-file-name switch.c %s | FileCheck %s
+// RUN: %clang_cc1 -fprofile-instrument=clang -fcoverage-mapping -dump-coverage-mapping -emit-llvm-only -std=c++1z -triple %itanium_abi_triple -main-file-name switch.cpp %s | FileCheck %s
+
                     // CHECK: foo
 void foo(int i) {   // CHECK-NEXT: File 0, [[@LINE]]:17 -> [[@LINE+8]]:2 = #0
   switch(i) {
   case 1:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+3]]:10 = #2
     return;
   case 2:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:10 = #3
     break;
   }
   int x = 0;        // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:2 = #1
 }
 
-void nop() {}
+int nop() { return 0; }
 
                     // CHECK: bar
 void bar(int i) {   // CHECK-NEXT: File 0, [[@LINE]]:17 -> [[@LINE+20]]:2 = #0
   switch (i)
     ;               // CHECK-NEXT: File 0, [[@LINE]]:5 -> [[@LINE]]:6 = 0
 
   switch (i) {      // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+16]]:2 = #1
   }
 
   switch (i)        // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+13]]:2 = #2
     nop();          // CHECK-NEXT: File 0, [[@LINE]]:5 -> [[@LINE]]:10 = 0
 
   switch (i)        // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+10]]:2 = #3
   case 1:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:10 = #5
     nop();
 
   switch (i) {      // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+6]]:2 = #4
     nop();          // CHECK-NEXT: File 0, [[@LINE]]:5 -> [[@LINE+2]]:10 = 0
   case 1:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:10 = #7
     nop();
   }
   nop();            // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:2 = #6
 }
 
+                    // CHECK: baz
+void baz() {        // CHECK-NEXT: File 0, [[@LINE]]:12 -> [[@LINE+5]]:2 = #0
+  switch (int i = true ? nop()  // CHECK-NEXT: [[@LINE]]:26 -> [[@LINE]]:31 = #2
+                       : nop(); // CHECK-NEXT: [[@LINE]]:26 -> [[@LINE]]:31 = (#0 - #2)
+          i) {}
+  nop();            // CHECK-NEXT: [[@LINE]]:3 -> [[@LINE+1]]:2 = #1
+}
+
                     // CHECK-NEXT: main
-int main() {        // CHECK-NEXT: File 0, [[@LINE]]:12 -> [[@LINE+34]]:2 = #0
+int main() {        // CHECK-NEXT: File 0, [[@LINE]]:12 -> [[@LINE+35]]:2 = #0
   int i = 0;
   switch(i) {
   case 0:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+7]]:10 = #2
     i = 1;
     break;
   case 1:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+2]]:10 = #3
     i = 2;
     break;
   default:          // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:10 = #4
     break;
   }
-  switch(i) {       // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+22]]:2 = #1
+  switch(i) {       // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+23]]:2 = #1
   case 0:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+6]]:10 = #6
     i = 1;
     break;
   case 1:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+3]]:10 = #7
     i = 2;
   default:          // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:10 = (#7 + #8)
     break;
   }
 
-  switch(i) {       // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+12]]:2 = #5
+  switch(i) {       // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+13]]:2 = #5
   case 1:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+5]]:11 = #10
   case 2:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+4]]:11 = (#10 + #11)
     i = 11;
   case 3:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+2]]:11 = ((#10 + #11) + #12)
   case 4:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:11 = (((#10 + #11) + #12) + #13)
     i = 99;
   }
 
-  foo(1);           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+2]]:11 = #9
+  foo(1);           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+3]]:11 = #9
   bar(1);
+  baz();
   return 0;
 }