llvm-symbolizer: prefer .dwo contents over fission-gmlt-like-data when .dwo file is present

Rather than relying on the gmlt-like data emitted into the .o/executable
which only contains the simple name of any inlined functions, use the
.dwo file if present.

Test symbolication with/without a .dwo, and the old test that was
testing behavior when no gmlt-like data was present. (I haven't included
a test of non-gmlt-like data + no .dwo (that would be akin to
symbolication with no debug info) but we could add one for completeness)

The test was simplified a bit to be a little clearer (unoptimized, force
inline, using a function call as the inlined entity) and regenerated
with ToT clang. For the no-gmlt-like-data case, I modified Clang back to
its old behavior temporarily & the .dwo file is identical so it is
shared between the two executables.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@267227 91177308-0d34-0410-b5e6-96231b3b80d8

Author: dwblaikie

lib/DebugInfo/DWARF/DWARFUnit.cpp

@@ -378,19 +378,14 @@ DWARFUnit::getInlinedChainForAddress(uint64_t Address) {
   // First, find a subprogram that contains the given address (the root
   // of inlined chain).
   const DWARFUnit *ChainCU = nullptr;
-  const DWARFDebugInfoEntryMinimal *SubprogramDIE =
-      getSubprogramForAddress(Address);
-  if (SubprogramDIE) {
+  const DWARFDebugInfoEntryMinimal *SubprogramDIE;
+  // Try to look for subprogram DIEs in the DWO file.
+  parseDWO();
+  if (DWO) {
+    if ((SubprogramDIE = DWO->getUnit()->getSubprogramForAddress(Address)))
+      ChainCU = DWO->getUnit();
+  } else if ((SubprogramDIE = getSubprogramForAddress(Address)))
     ChainCU = this;
-  } else {
-    // Try to look for subprogram DIEs in the DWO file.
-    parseDWO();
-    if (DWO.get()) {
-      SubprogramDIE = DWO->getUnit()->getSubprogramForAddress(Address);
-      if (SubprogramDIE)
-        ChainCU = DWO->getUnit();
-    }
-  }
 
   // Get inlined chain rooted at this subprogram DIE.
   if (!SubprogramDIE)

test/DebugInfo/Inputs/split-dwarf-test

@@ -1,13 +1,16 @@
-int foo(int a) {
-  return a + 1;
+void f1() {
 }
 
-int main(int argc, char *argv[]) {
-  return foo(argc);
+inline __attribute__((always_inline)) void f2() {
+  f1();
+}
+
+int main() {
+  f2();
 }
 
 // Build instructions:
-// 1) clang++ -### -O2 -gsplit-dwarf.cc split-dwarf-test.cc -o split-dwarf-test
+// 1) clang++ -### -gsplit-dwarf split-dwarf-test.cc -o split-dwarf-test
 // 2) Replace the value "-fdebug-compilation-dir" flag to "Output"
 //      (this is the temp directory used by lit).
 // 3) Manually run clang-cc1, objcopy and ld invocations.

test/DebugInfo/Inputs/split-dwarf-test-nogmlt

@@ -20,12 +20,27 @@ RUN: echo "%p/Inputs/llvm-symbolizer-dwo-test 0x400514" >> %t.input
 RUN: echo "%p/Inputs/fission-ranges.elf-x86_64 0x720" >> %t.input
 RUN: echo "%p/Inputs/arange-overlap.elf-x86_64 0x714" >> %t.input
 RUN: cp %p/Inputs/split-dwarf-test.dwo %T
-RUN: echo "%p/Inputs/split-dwarf-test 0x4004d0" >> %t.input
-RUN: echo "%p/Inputs/split-dwarf-test 0x4004c0" >> %t.input
+RUN: echo "%p/Inputs/split-dwarf-test 0x4005d4" >> %t.input
+RUN: echo "%p/Inputs/split-dwarf-test 0x4005c4" >> %t.input
 RUN: echo "%p/Inputs/cross-cu-inlining.x86_64-macho.o 0x17" >> %t.input
 
 RUN: llvm-symbolizer --functions=linkage --inlining --demangle=false \
-RUN:    --default-arch=i386 < %t.input | FileCheck %s
+RUN:    --default-arch=i386 < %t.input | FileCheck --check-prefix=CHECK --check-prefix=SPLIT --check-prefix=DWO %s
+
+Ensure we get the same results in the absence of gmlt-like data in the executable but the presence of a .dwo file
+
+RUN: echo "%p/Inputs/split-dwarf-test-nogmlt 0x4005d4" >> %t.input
+RUN: echo "%p/Inputs/split-dwarf-test-nogmlt 0x4005c4" >> %t.input
+RUN: llvm-symbolizer --functions=linkage --inlining --demangle=false \
+RUN:    --default-arch=i386 < %t.input | FileCheck --check-prefix=SPLIT --check-prefix=DWO %s
+
+Ensure we get gmlt like results in the absence of a .dwo file but the presence of gmlt-like data in the executable
+
+RUN: rm %T/split-dwarf-test.dwo
+RUN: echo "%p/Inputs/split-dwarf-test 0x4005d4" >> %t.input
+RUN: echo "%p/Inputs/split-dwarf-test 0x4005c4" >> %t.input
+RUN: llvm-symbolizer --functions=linkage --inlining --demangle=false \
+RUN:    --default-arch=i386 < %t.input | FileCheck --check-prefix=SPLIT --check-prefix=NODWO %s
 
 CHECK:       main
 CHECK-NEXT: /tmp/dbginfo{{[/\\]}}dwarfdump-test.cc:16
@@ -102,13 +117,14 @@ CHECK-NEXT: {{.*}}fission-ranges.cc:6
 CHECK: _ZN1S3bazEv
 CHECK-NEXT: {{.*}}arange-overlap.cc:6
 
-CHECK: _Z3fooi
-CHECK-NEXT: {{.*}}split-dwarf-test.cc
-CHECK-NEXT: main
-CHECK-NEXT: {{.*}}split-dwarf-test.cc
+DWO: _Z2f2v
+NODWO: {{^f2$}}
+SPLIT-NEXT: {{.*}}split-dwarf-test.cc
+SPLIT-NEXT: main
+SPLIT-NEXT: {{.*}}split-dwarf-test.cc
 
-CHECK: _Z3fooi
-CHECK-NEXT: {{.*}}split-dwarf-test.cc
+SPLIT: _Z2f1v
+SPLIT-NEXT: {{.*}}split-dwarf-test.cc
 
 ; func has been inlined into main by LTO. Check that the symbolizer is able
 ; to resolve the cross-cu reference and retrieve func's name