[coverage] Special-case calls to noreturn functions.

[efriedma]

Summary

The code after a noreturn call doesn't execute.

The pattern in the testcase is pretty common in LLVM (a switch with a default case that calls llvm_unreachable).

[vsk]

Thanks, lgtm.

[efriedma]

This was reverted.

Failing function, from include/clang/AST/Type.h:

inline bool Type::isImageType() const {
#define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) is##Id##Type() ||
  return
#include "clang/Basic/OpenCLImageTypes.def"
      0; // end boolean or operation
}

There are no noreturn calls here. I think the problem is that we're missing a call to handleFileExit() somewhere. I'll post an updated patch soon.

[efriedma]

Add missing call to handleFileExit().

Not sure I'm really calling it in the right place, but this seems to work.

[vsk]

I tested this out on clang's ItaniumMangle.cpp and the crash is resolved.

lib/CodeGen/CoverageMappingGen.cpp

723 ↗

(On Diff #109838)

This is doing the right thing. I think it should just be replaced by a call to VisitStmt(E), though, as that's clearer.

[efriedma]

Update to call VisitStmt(E)

[vsk]

Thanks, lgtm.

cfe/trunk/lib/CodeGen/CoverageMappingGen.cpp

struct CounterCoverageMappingBuilder
 
   void VisitContinueStmt(const ContinueStmt *S) {
     assert(!BreakContinueStack.empty() && "continue stmt not in a loop!");
     BreakContinueStack.back().ContinueCount = addCounters(
         BreakContinueStack.back().ContinueCount, getRegion().getCounter());
     terminateRegion(S);
   }
 
+  void VisitCallExpr(const CallExpr *E) {
+    VisitStmt(E);
+
+    // Terminate the region when we hit a noreturn function.
+    // (This is helpful dealing with switch statements.)
+    QualType CalleeType = E->getCallee()->getType();
+    if (getFunctionExtInfo(*CalleeType).getNoReturn())
+      terminateRegion(E);
+  }
+
   void VisitWhileStmt(const WhileStmt *S) {
     extendRegion(S);
 
     Counter ParentCount = getRegion().getCounter();
     Counter BodyCount = getRegionCounter(S);
 
     // Handle the body first so that we can get the backedge count.
     BreakContinueStack.push_back(BreakContinue());

cfe/trunk/test/CoverageMapping/md.cpp

void foo(MD i) {
   }
 
   if (false)
     nop();
   #define HANDLE_MD(X) else if (i == MD::X) { nop(); }
   #include "Inputs/md.def"
 }
 
+// CHECK: bar
+// CHECK-NEXT: File 0, [[@LINE+3]]:12 -> [[@LINE+8]]:2 = #0
+bool isVal1();
+bool isVal2();
+bool bar() {
+ #define HANDLE_MD(X) is##X() ||
+  return
+#include "Inputs/md.def"
+  0;
+}
+
 int main(int argc, const char *argv[]) {
   foo(MD::Val1);
   return 0;
 }

cfe/trunk/test/CoverageMapping/switch.cpp

case 2:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+2]]:10 = (#2 + #3)
     i = 11;
     break;
   case 3:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+3]]:10 = #4
   case 4:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+2]]:10 = (#4 + #5)
     i = 99;
     break;
   }
 }
+
+void abort(void) __attribute((noreturn));
+                   // CHECK: noret
+int noret(int x) { // CHECK-NEXT: File 0, [[@LINE]]:18 -> [[@LINE+9]]:2
+  switch (x) {
+  default:         // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:12
+    abort();
+  case 1:         // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:13
+    return 5;
+  case 2:         // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:14
+    return 10;
+  }
+}