[PatchableFunction] Use an empty DebugLoc
The current FirstMI.getDebugLoc() is actually null in almost all cases.
If it isn't, the generated .loc will be considered initial. The .loc
will have the prologue_end flag and terminate the prologue prematurely.
Also use an overload of BuildMI that will not prepend
PATCHABLE_FUNCTION_ENTRY to a MachineInstr bundle.
diff --git a/llvm/lib/CodeGen/PatchableFunction.cpp b/llvm/lib/CodeGen/PatchableFunction.cpp
index a846639..ca44b7a 100644
--- a/llvm/lib/CodeGen/PatchableFunction.cpp
+++ b/llvm/lib/CodeGen/PatchableFunction.cpp
@@ -58,14 +58,9 @@
if (MF.getFunction().hasFnAttribute("patchable-function-entry")) {
MachineBasicBlock &FirstMBB = *MF.begin();
const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
- if (FirstMBB.empty()) {
- BuildMI(&FirstMBB, DebugLoc(),
- TII->get(TargetOpcode::PATCHABLE_FUNCTION_ENTER));
- } else {
- MachineInstr &FirstMI = *FirstMBB.begin();
- BuildMI(FirstMBB, FirstMI, FirstMI.getDebugLoc(),
- TII->get(TargetOpcode::PATCHABLE_FUNCTION_ENTER));
- }
+ // The initial .loc covers PATCHABLE_FUNCTION_ENTER.
+ BuildMI(FirstMBB, FirstMBB.begin(), DebugLoc(),
+ TII->get(TargetOpcode::PATCHABLE_FUNCTION_ENTER));
return true;
}