[llvm] [llvm-readobj] Dump callgraph section info for ELF (PR #157499)

[Paul Kirth via llvm-commits]

================
@@ -0,0 +1,759 @@
+## Tests how --call-graph-info prints the call graph information.
+# RUN: yaml2obj --docnum=1 %s -o %t
+# RUN: llvm-readelf --call-graph-info %t 2>&1 | FileCheck %s --match-full-lines -DFILE=%t
+# RUN: llvm-readelf --elf-output-style=LLVM --call-graph-info %t 2>&1 | FileCheck %s --match-full-lines --check-prefix=LLVM -DFILE=%t
+# RUN: llvm-readelf --elf-output-style=JSON --pretty-print --call-graph-info %t 2>&1 | FileCheck %s --match-full-lines --check-prefix=JSON -DFILE=%t
+
+# Yaml input is obtained by compiling the below source to object with:
+#   clang -fexperimental-call-graph-section test.c -o test.o
+# then to yaml with:
+#   obj2yaml test.o > test.yaml
+# Remove ProgramHeaders if obj2yaml fails.
+
+# The content of the .callgraph section is fixed with this yaml in raw format.
+
+# Source:
+#   void foo() {}
+#
+#   void bar() {}
+#
+#   int baz(char a) {
+#     return 0;
+#   }
+#
+#   int main() {
+#     // Indirect calls.
+#     void (*fp_foo)() = foo;
+#     fp_foo();
+#
+#     void (*fp_bar)() = bar;
+#     fp_bar();
+#
+#     char a;
+#     int (*fp_baz)(char) = baz;
+#     fp_baz(a);
+#
+#     // Direct calls.
+#     foo();
+#     bar();
+#     baz(a);
+#
+#     return 0;
+#   }
+
+# CHECK: Call graph section '.llvm.callgraph' contains 4 entries:
+# CHECK-EMPTY:
+# CHECK-NEXT: Entry 0:
+# CHECK-NEXT:    Address:          0x1790 <foo>
+# CHECK-NEXT:    Indirect Target:  Yes
+# CHECK-NEXT:    Type ID:          0x3ecbeef531f74424
+# CHECK-NEXT:    Direct Callees (0):
+# CHECK-NEXT:    Indirect Callees by Type ID (0):
+# CHECK-EMPTY:
+# CHECK-NEXT: Entry 1:
+# CHECK-NEXT:    Address:          0x17a0 <bar>
+# CHECK-NEXT:    Indirect Target:  Yes
+# CHECK-NEXT:    Type ID:          0x3ecbeef531f74424
+# CHECK-NEXT:    Direct Callees (0):
+# CHECK-NEXT:    Indirect Callees by Type ID (0):
+# CHECK-EMPTY:
+# CHECK-NEXT: Entry 2:
+# CHECK-NEXT:    Address:          0x17b0 <baz>
+# CHECK-NEXT:    Indirect Target:  Yes
+# CHECK-NEXT:    Type ID:          0x308e4b8159bc8654
+# CHECK-NEXT:    Direct Callees (0):
+# CHECK-NEXT:    Indirect Callees by Type ID (0):
+# CHECK-EMPTY:
+# CHECK-NEXT: Entry 3:
+# CHECK-NEXT:    Address:          0x17c0 <main>
+# CHECK-NEXT:    Indirect Target:  Yes
+# CHECK-NEXT:    Type ID:          0xfa6809609a76afca
+# CHECK-NEXT:    Direct Callees (3):
+# CHECK-NEXT:       Address:          0x1790 <foo>
+# CHECK-NEXT:       Address:          0x17a0 <bar>
+# CHECK-NEXT:       Address:          0x17b0 <baz>
+# CHECK-NEXT:    Indirect Callees by Type ID (2):
+# CHECK-NEXT:      0x3ecbeef531f74424
+# CHECK-NEXT:      0x308e4b8159bc8654
+
+# LLVM: callgraph_info [
+# LLVM-NEXT:     Function {
+# LLVM-NEXT:       Functions: [foo]
+# LLVM-NEXT:       Address: 0x1790
+# LLVM-NEXT:       Version: 0
+# LLVM-NEXT:       IsIndirectTarget: Yes
+# LLVM-NEXT:       TypeId: 0x3ECBEEF531F74424
+# LLVM-NEXT:       NumDirectCallees: 0
+# LLVM-NEXT:       DirectCallees [
+# LLVM-NEXT:       ]
+# LLVM-NEXT:       NumIndirectTargetTypeIDs: 0
+# LLVM-NEXT:       IndirectTypeIDs [
+# LLVM-NEXT:       ]
+# LLVM-NEXT:     }
+# LLVM-NEXT:     Function {
+# LLVM-NEXT:       Functions: [bar]
+# LLVM-NEXT:       Address: 0x17A0
+# LLVM-NEXT:       Version: 0
+# LLVM-NEXT:       IsIndirectTarget: Yes
+# LLVM-NEXT:       TypeId: 0x3ECBEEF531F74424
+# LLVM-NEXT:       NumDirectCallees: 0
+# LLVM-NEXT:       DirectCallees [
+# LLVM-NEXT:       ]
+# LLVM-NEXT:       NumIndirectTargetTypeIDs: 0
+# LLVM-NEXT:       IndirectTypeIDs [
+# LLVM-NEXT:       ]
+# LLVM-NEXT:     }
+# LLVM-NEXT:     Function {
+# LLVM-NEXT:       Functions: [baz]
+# LLVM-NEXT:       Address: 0x17B0
+# LLVM-NEXT:       Version: 0
+# LLVM-NEXT:       IsIndirectTarget: Yes
+# LLVM-NEXT:       TypeId: 0x308E4B8159BC8654
+# LLVM-NEXT:       NumDirectCallees: 0
+# LLVM-NEXT:       DirectCallees [
+# LLVM-NEXT:       ]
+# LLVM-NEXT:       NumIndirectTargetTypeIDs: 0
+# LLVM-NEXT:       IndirectTypeIDs [
+# LLVM-NEXT:       ]
+# LLVM-NEXT:     }
+# LLVM-NEXT:     Function {
+# LLVM-NEXT:       Functions: [main]
+# LLVM-NEXT:       Address: 0x17C0
+# LLVM-NEXT:       Version: 0
+# LLVM-NEXT:       IsIndirectTarget: Yes
+# LLVM-NEXT:       TypeId: 0xFA6809609A76AFCA
+# LLVM-NEXT:       NumDirectCallees: 3
+# LLVM-NEXT:       DirectCallees [
+# LLVM-NEXT:         Entry {
+# LLVM-NEXT:           Functions: [foo]
+# LLVM-NEXT:           Address: 0x1790
+# LLVM-NEXT:         }
+# LLVM-NEXT:         Entry {
+# LLVM-NEXT:           Functions: [bar]
+# LLVM-NEXT:           Address: 0x17A0
+# LLVM-NEXT:         }
+# LLVM-NEXT:         Entry {
+# LLVM-NEXT:           Functions: [baz]
+# LLVM-NEXT:           Address: 0x17B0
+# LLVM-NEXT:         }
+# LLVM-NEXT:       ]
+# LLVM-NEXT:       NumIndirectTargetTypeIDs: 2
+# LLVM-NEXT:       IndirectTypeIDs [
+# LLVM-NEXT:         Entry {
+# LLVM-NEXT:           TypeId: 0x3ECBEEF531F74424
+# LLVM-NEXT:         }
+# LLVM-NEXT:         Entry {
+# LLVM-NEXT:           TypeId: 0x308E4B8159BC8654
+# LLVM-NEXT:         }
+# LLVM-NEXT:       ]
+# LLVM-NEXT:     }
+# LLVM-NEXT:   ]
+
+
+# JSON:     "callgraph_info": [
+# JSON-NEXT:      {
+# JSON-NEXT:        "Function": {
+# JSON-NEXT:          "Functions": [
+# JSON-NEXT:            "foo"
+# JSON-NEXT:          ],
+# JSON-NEXT:          "Address": 6032,
+# JSON-NEXT:          "Version": 0,
+# JSON-NEXT:          "IsIndirectTarget": true,
+# JSON-NEXT:          "TypeId": 4524972987496481828,
+# JSON-NEXT:          "NumDirectCallees": 0,
+# JSON-NEXT:          "DirectCallees": [],
+# JSON-NEXT:          "NumIndirectTargetTypeIDs": 0,
+# JSON-NEXT:          "IndirectTypeIDs": []
+# JSON-NEXT:        }
+# JSON-NEXT:      },
----------------
ilovepi wrote:

```suggestion
# JSON:     "CallGraph":  [
# JSON-NEXT:      {
# JSON-NEXT:          "Name":"foo",
# JSON-NEXT:          "Address": 6032,
# JSON-NEXT:          "Version": 0,
# JSON-NEXT:          "IsIndirectTarget": true,
# JSON-NEXT:          "TypeId": 4524972987496481828,
# JSON-NEXT:          "NumDirectCallees": 0,
# JSON-NEXT:          "DirectCallees": [],
# JSON-NEXT:          "NumIndirectTargetTypeIDs": 0,
# JSON-NEXT:          "IndirectTypeIDs": []
# JSON-NEXT:      },
```
This is more along the lines of what I'd expect.  It gets rid of  the somewhat redundant key/value pairs and uses a name field instead. IMO this will be a bit nicer to use programmatically, as well.


https://github.com/llvm/llvm-project/pull/157499