Reorder fields in callgraph section.

Author: Prabhuk

llvm/docs/CallGraphSection.md

@@ -13,6 +13,6 @@ Each record in the `.callgraph` section has the following binary layout:
 | Function Entry PC                      | `uintptr_t`   | 32/64       | The address of the function's entry point.                                                              |
 | Function Type ID                       | `uint64_t`    | 64          | The type ID of the function. This field is non-zero if the function is a potential indirect call target and its type is known. |
 | Number of Unique Direct Callees        | `ULEB128`     | Variable    | The number of unique direct call destinations from this function. This field is only present if there is at least one direct callee. |
-| Number of Unique Indirect Target Type IDs| `ULEB128`     | Variable    | The number of unique indirect call target type IDs. This field is only present if there is at least one indirect target type ID. |
 | Direct Callees Array                   | `uintptr_t[]` | Variable    | An array of unique direct callee entry point addresses.                                                 |
+| Number of Unique Indirect Target Type IDs| `ULEB128`     | Variable    | The number of unique indirect call target type IDs. This field is only present if there is at least one indirect target type ID. |
 | Indirect Target Type IDs Array         | `uint64_t[]`  | Variable    | An array of unique indirect call target type IDs.                                                       |

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -1713,11 +1713,11 @@ void AsmPrinter::emitCallGraphSection(const MachineFunction &MF,
   //    c. LSB bit 2 is set to 1 if there are indirect callees.
   //    d. Rest of the 5 bits in Flags are reserved for any future use.
   // 3) Function entry PC.
-  // 4) FunctionTypeID if the function is indirect target and its type id is
-  // known, otherwise it is set to 0.
+  // 4) FunctionTypeID if the function is indirect target and its type id
+  //    is known, otherwise it is set to 0.
   // 5) Number of unique direct callees, if at least one exists.
-  // 6) Number of unique indirect target type IDs, if at least one exists.
-  // 7) For each unique direct callee, the callee's PC.
+  // 6) For each unique direct callee, the callee's PC.
+  // 7) Number of unique indirect target type IDs, if at least one exists.
   // 8) Each unique indirect target type id.
   OutStreamer->emitInt8(CallGraphSectionFormatVersion::V_0);
   OutStreamer->emitInt8(Flags);
@@ -1728,16 +1728,18 @@ void AsmPrinter::emitCallGraphSection(const MachineFunction &MF,
   else
     OutStreamer->emitInt64(0);
 
-  if (DirectCallees.size() > 0)
+  if (DirectCallees.size() > 0) {
     OutStreamer->emitULEB128IntValue(DirectCallees.size());
-  if (IndirectCalleeTypeIDs.size() > 0)
+    for (const auto &CalleeSymbol : DirectCallees)
+      OutStreamer->emitSymbolValue(CalleeSymbol, TM.getProgramPointerSize());
+    FuncCGInfo.DirectCallees.clear();
+  }
+  if (IndirectCalleeTypeIDs.size() > 0) {
     OutStreamer->emitULEB128IntValue(IndirectCalleeTypeIDs.size());
-  for (const auto &CalleeSymbol : DirectCallees)
-    OutStreamer->emitSymbolValue(CalleeSymbol, TM.getProgramPointerSize());
-  FuncCGInfo.DirectCallees.clear();
-  for (const auto &CalleeTypeId : IndirectCalleeTypeIDs)
-    OutStreamer->emitInt64(CalleeTypeId);
-  FuncCGInfo.IndirectCalleeTypeIDs.clear();
+    for (const auto &CalleeTypeId : IndirectCalleeTypeIDs)
+      OutStreamer->emitInt64(CalleeTypeId);
+    FuncCGInfo.IndirectCalleeTypeIDs.clear();
+  }
   // End of emitting call graph section contents.
   OutStreamer->popSection();
 }

llvm/test/CodeGen/X86/call-graph-section-assembly.ll

@@ -47,12 +47,12 @@ entry:
 ; CHECK-NEXT: .quad   0
 ;; Number of unique direct callees.
 ; CHECK-NEXT: .byte	  3
-;; Number of unique indirect target type IDs.
-; CHECK-NEXT: .byte   3
 ;; Direct callees.
 ; CHECK-NEXT: .quad	direct_foo
 ; CHECK-NEXT: .quad	direct_bar
 ; CHECK-NEXT: .quad	direct_baz
+;; Number of unique indirect target type IDs.
+; CHECK-NEXT: .byte   3
 ;; Indirect type IDs.
 ; CHECK-NEXT: .quad   4524972987496481828
 ; CHECK-NEXT: .quad   3498816979441845844