[llvm-cov] Strip redundant path components from filenames (fix PR31982)

Instead of stripping the longest common prefix off of the filenames in a
report, strip out the longest chain of redundant path components. This
fixes the case in PR31982, where there are two files with the same
prefix, and stripping out the LCP makes things less intelligible.

llvm-svn: 296029

2 files changed, 13 insertions, 7 deletions

diff --git a/llvm/test/tools/llvm-cov/Inputs/multiple-files2.covmapping b/llvm/test/tools/llvm-cov/Inputs/multiple-files2.covmapping
new file mode 100644
index 00000000000..770817a5380
--- /dev/null
+++ b/llvm/test/tools/llvm-cov/Inputs/multiple-files2.covmapping
diff --git a/llvm/test/tools/llvm-cov/multiple-files.test b/llvm/test/tools/llvm-cov/multiple-files.test
index 0b3fb855fed..d0dbdd8c0fc 100644
--- a/llvm/test/tools/llvm-cov/multiple-files.test
+++ b/llvm/test/tools/llvm-cov/multiple-files.test
@@ -1,9 +1,15 @@
 // RUN: llvm-profdata merge %S/Inputs/multiple-files.proftext -o %t.profdata
-// RUN: llvm-cov report %S/Inputs/multiple-files.covmapping -instr-profile %t.profdata | FileCheck %s
+// RUN: llvm-cov report %S/Inputs/multiple-files.covmapping -instr-profile %t.profdata | FileCheck %s -check-prefix=MANY_COMPONENTS
+// RUN: llvm-cov report %S/Inputs/multiple-files2.covmapping -instr-profile %t.profdata | FileCheck %s -check-prefix=ONE_COMPONENT
 
-// CHECK: Filename
-// CHECK-NEXT: ---
-// CHECK-NEXT: {{^}}a{{[/\\]}}f2.c
-// CHECK-NEXT: {{^}}b{{[/\\]}}c{{[/\\]}}f4.c
-// CHECK-NEXT: {{^}}b{{[/\\]}}f3.c
-// CHECK-NEXT: {{^}}f1.c
+// MANY_COMPONENTS: Filename
+// MANY_COMPONENTS-NEXT: ---
+// MANY_COMPONENTS-NEXT: {{^}}a{{[/\\]}}f2.c
+// MANY_COMPONENTS-NEXT: {{^}}b{{[/\\]}}c{{[/\\]}}f4.c
+// MANY_COMPONENTS-NEXT: {{^}}b{{[/\\]}}f3.c
+// MANY_COMPONENTS-NEXT: {{^}}f1.c
+
+// ONE_COMPONENT: Filename
+// ONE_COMPONENT-NEXT: ---
+// ONE_COMPONENT-NEXT: {{^}}cov.c
+// ONE_COMPONENT-NEXT: {{^}}cov.h