[PATCH] D36250: [coverage] Special-case calls to noreturn functions.

[Eli Friedman via Phabricator via cfe-commits]

efriedma created this revision.

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).


Repository:
  rL LLVM

https://reviews.llvm.org/D36250

Files:
  lib/CodeGen/CoverageMappingGen.cpp
  test/CoverageMapping/switch.cpp


Index: test/CoverageMapping/switch.cpp
===================================================================
--- test/CoverageMapping/switch.cpp
+++ test/CoverageMapping/switch.cpp
@@ -97,3 +97,16 @@
     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;
+  }
+}
Index: lib/CodeGen/CoverageMappingGen.cpp
===================================================================
--- lib/CodeGen/CoverageMappingGen.cpp
+++ lib/CodeGen/CoverageMappingGen.cpp
@@ -716,6 +716,18 @@
     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);
 


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