r309995 - [coverage] Special-case calls to noreturn functions.

[Eli Friedman via cfe-commits]

Author: efriedma
Date: Thu Aug  3 15:27:36 2017
New Revision: 309995

URL: http://llvm.org/viewvc/llvm-project?rev=309995&view=rev
Log:
[coverage] Special-case calls to noreturn functions.

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).

Differential Revision: https://reviews.llvm.org/D36250


Modified:
    cfe/trunk/lib/CodeGen/CoverageMappingGen.cpp
    cfe/trunk/test/CoverageMapping/switch.cpp

Modified: cfe/trunk/lib/CodeGen/CoverageMappingGen.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CoverageMappingGen.cpp?rev=309995&r1=309994&r2=309995&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CoverageMappingGen.cpp (original)
+++ cfe/trunk/lib/CodeGen/CoverageMappingGen.cpp Thu Aug  3 15:27:36 2017
@@ -716,6 +716,18 @@ struct CounterCoverageMappingBuilder
     terminateRegion(S);
   }
 
+  void VisitCallExpr(const CallExpr *E) {
+    extendRegion(E);
+    for (const Stmt *Child : E->children())
+      this->Visit(Child);
+
+    // 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);
 

Modified: cfe/trunk/test/CoverageMapping/switch.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CoverageMapping/switch.cpp?rev=309995&r1=309994&r2=309995&view=diff
==============================================================================
--- cfe/trunk/test/CoverageMapping/switch.cpp (original)
+++ cfe/trunk/test/CoverageMapping/switch.cpp Thu Aug  3 15:27:36 2017
@@ -97,3 +97,16 @@ int fallthrough(int i) { // CHECK-NEXT:
     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;
+  }
+}