[Coverage] Emit a gap region to cover switch bodies

Emit a gap region beginning where the switch body begins. This sets line
execution counts in the areas between non-overlapping cases to 0.

This also removes some special handling of the first case in a switch:
these are now treated like any other case.

This does not resolve an outstanding issue with case statement regions
that do not end when a region is terminated. But it should address
llvm.org/PR44011.

Differential Revision: https://reviews.llvm.org/D70571

2 files changed, 24 insertions, 11 deletions

diff --git a/clang/test/CoverageMapping/switch.cpp b/clang/test/CoverageMapping/switch.cpp
index 30c64922201..25ea4053f4e 100644
--- a/clang/test/CoverageMapping/switch.cpp
+++ b/clang/test/CoverageMapping/switch.cpp
@@ -2,11 +2,11 @@
 
                     // CHECK: foo
 void foo(int i) {   // CHECK-NEXT: File 0, [[@LINE]]:17 -> [[@LINE+8]]:2 = #0
-  switch(i) {
+  switch(i) {       // CHECK-NEXT: Gap,File 0, [[@LINE]]:13 -> [[@LINE+4]]:10 = 0
   case 1:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:11 = #2
     return;
   case 2:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:10 = #3
-    break;          // CHECK-NEXT: File 0, [[@LINE]]:10 -> [[@LINE+2]]:3 = #1
+    break;          // CHECK-NEXT: Gap,File 0, [[@LINE]]:10 -> [[@LINE+2]]:3 = #1
   }
   int x = 0;        // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:2 = #1
 }
@@ -29,7 +29,7 @@ void bar(int i) {   // CHECK-NEXT: File 0, [[@LINE]]:17 -> [[@LINE+20]]:2 = #0
     nop();
 
   switch (i) {      // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+6]]:2 = #4
-    nop();          // CHECK-NEXT: File 0, [[@LINE]]:5 -> [[@LINE+2]]:10 = 0
+    nop();          // CHECK-NEXT: Gap,File 0, [[@LINE-1]]:14 -> [[@LINE+2]]:10 = 0
   case 1:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:10 = #7
     nop();
   }
@@ -47,7 +47,7 @@ void baz() {        // CHECK-NEXT: File 0, [[@LINE]]:12 -> [[@LINE+5]]:2 = #0
                     // CHECK-NEXT: main
 int main() {        // CHECK-NEXT: File 0, [[@LINE]]:12 -> [[@LINE+35]]:2 = #0
   int i = 0;
-  switch(i) {
+  switch(i) {       // CHECK-NEXT: Gap,File 0, [[@LINE]]:13 -> [[@LINE+8]]:10 = 0
   case 0:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+2]]:10 = #2
     i = 1;
     break;
@@ -58,16 +58,16 @@ int main() {        // CHECK-NEXT: File 0, [[@LINE]]:12 -> [[@LINE+35]]:2 = #0
     break;          // CHECK-NEXT: File 0, [[@LINE]]:10 -> [[@LINE+2]]:3 = #1
   }
   switch(i) {       // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+23]]:2 = #1
-  case 0:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+2]]:10 = #6
-    i = 1;
+  case 0:           // CHECK-NEXT: Gap,File 0, [[@LINE-1]]:13 -> [[@LINE+6]]:10 = 0
+    i = 1;          // CHECK-NEXT: File 0, [[@LINE-1]]:3 -> [[@LINE+1]]:10 = #6
     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;          // CHECK-NEXT: File 0, [[@LINE]]:10 -> [[@LINE+3]]:3 = #5
   }
-
-  switch(i) {       // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+13]]:2 = #5
+                    // CHECK-NEXT: File 0, [[@LINE+1]]:3 -> [[@LINE+14]]:2 = #5
+  switch(i) {       // CHECK-NEXT: Gap,File 0, [[@LINE]]:13 -> [[@LINE+6]]:11 = 0
   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;
@@ -82,10 +82,23 @@ int main() {        // CHECK-NEXT: File 0, [[@LINE]]:12 -> [[@LINE+35]]:2 = #0
   return 0;
 }
 
+                     // CHECK: pr44011
+int pr44011(int i) { // CHECK-NEXT: File 0, [[@LINE]]:20 -> {{.*}}:2 = #0
+  switch (i) {       // CHECK-NEXT: Gap,File 0, [[@LINE]]:14 -> [[@LINE+6]]:13 = 0
+
+  case 1:            // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:13 = #2
+    return 0;
+
+  default:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:13 = #3
+    return 1;
+  }
+} // A region for counter #1 is missing due to the missing return.
+
+
 // FIXME: End location for "case 1" shouldn't point at the end of the switch.
                          // CHECK: fallthrough
 int fallthrough(int i) { // CHECK-NEXT: File 0, [[@LINE]]:24 -> [[@LINE+12]]:2 = #0
-  switch(i) {
+  switch(i) {       // CHECK-NEXT: Gap,File 0, [[@LINE]]:13 -> [[@LINE+9]]:10 = 0
   case 1:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+8]]:10 = #2
     i = 23;
   case 2:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+2]]:10 = (#2 + #3)
@@ -101,7 +114,7 @@ int fallthrough(int i) { // CHECK-NEXT: File 0, [[@LINE]]:24 -> [[@LINE+12]]:2 =
 void abort(void) __attribute((noreturn));
                    // CHECK: noret
 int noret(int x) { // CHECK-NEXT: File 0, [[@LINE]]:18 -> [[@LINE+9]]:2
-  switch (x) {
+  switch (x) {     // CHECK-NEXT: Gap,File 0, [[@LINE]]:14 -> [[@LINE+6]]:14 = 0
   default:         // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:12
     abort();
   case 1:         // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:13
diff --git a/clang/test/CoverageMapping/switchmacro.c b/clang/test/CoverageMapping/switchmacro.c
index f4c14f798f0..fc0392fb91e 100644
--- a/clang/test/CoverageMapping/switchmacro.c
+++ b/clang/test/CoverageMapping/switchmacro.c
@@ -4,7 +4,7 @@
 
 // CHECK: foo
 int foo(int i) { // CHECK-NEXT: File 0, [[@LINE]]:16 -> {{[0-9]+}}:2 = #0
-  switch (i) {
+  switch (i) {   // CHECK-NEXT: Gap,File 0, [[@LINE]]:14 -> {{[0-9]+}}:11 = 0
   default:       // CHECK-NEXT: File 0, [[@LINE]]:3 -> {{[0-9]+}}:11 = #2
     if (i == 1)  // CHECK-NEXT: File 0, [[@LINE]]:9 -> [[@LINE]]:15 = #2
       return 0;  // CHECK: File 0, [[@LINE]]:7 -> [[@LINE]]:15 = #3