[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;
}
diff --git a/llvm/test/CodeGen/AArch64/patchable-function-entry-empty.mir b/llvm/test/CodeGen/AArch64/patchable-function-entry-empty.mir
index 032e07a..3651329 100644
--- a/llvm/test/CodeGen/AArch64/patchable-function-entry-empty.mir
+++ b/llvm/test/CodeGen/AArch64/patchable-function-entry-empty.mir
@@ -1,15 +1,11 @@
# RUN: llc -mtriple=aarch64 -run-pass=patchable-function %s -o - | FileCheck %s
+## The initial .loc covers PATCHABLE_FUNCTION_ENTER.
+## Emitting a new .loc may create a prologue_end prematurely.
# CHECK: name: empty
# CHECK: bb.0.entry
-# CHECK: PATCHABLE_FUNCTION_ENTER debug-location !DILocation(line: 1,
-# CHECK-NEXT: RET undef $lr, debug-location !DILocation(line: 1,
-
-## Empty entry MBB, no debug location.
-# CHECK: name: empty_entry
-# CHECK: bb.0.entry
# CHECK: PATCHABLE_FUNCTION_ENTER{{$}}
-# CHECK: bb.1.here
+# CHECK-NEXT: RET undef $lr, debug-location !DILocation(line: 1,
--- |
define void @empty() #0 !dbg !7 {
@@ -17,13 +13,6 @@
ret void, !dbg !10
}
- define void @empty_entry() #0 !dbg !11 {
- entry:
- br label %here
- here:
- ret void, !dbg !12
- }
-
attributes #0 = { "patchable-function-entry"="1" }
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 11.0.0 ", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
!1 = !DIFile(filename: "a.c", directory: "/tmp")
@@ -36,8 +25,6 @@
!8 = !DISubroutineType(types: !9)
!9 = !{null}
!10 = !DILocation(line: 1, column: 61, scope: !7)
- !11 = distinct !DISubprogram(name: "empty_entry", scope: !1, file: !1, line: 2, type: !8, scopeLine: 2, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
- !12 = !DILocation(line: 2, column: 61, scope: !11)
...
---
@@ -50,15 +37,3 @@
RET undef $lr, debug-location !10
...
----
-name: empty_entry
-alignment: 4
-tracksRegLiveness: true
-body: |
- bb.0.entry:
- liveins: $lr
- bb.1.here:
- liveins: $lr
- RET undef $lr, debug-location !12
-
-...