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[PatchableFunction] Allow empty entry MachineBasicBlock 

Reviewed By: nickdesaulniers

Differential Revision: https://reviews.llvm.org/D73301
This commit is contained in:
Fangrui Song 2020-01-23 14:46:28 -08:00
parent 0d61cd25a6
commit 50a3ff30e1
2 changed files with 72 additions and 3 deletions
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7
llvm/lib/CodeGen/PatchableFunction.cpp
View File

@ -57,10 +57,15 @@ static bool doesNotGeneratecode(const MachineInstr &MI) {
bool PatchableFunction::runOnMachineFunction(MachineFunction &MF) {
if (MF.getFunction().hasFnAttribute("patchable-function-entry")) {
MachineBasicBlock &FirstMBB = *MF.begin();
MachineInstr &FirstMI = *FirstMBB.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));
}
return true;
}

64
llvm/test/CodeGen/AArch64/patchable-function-entry-empty.mir Normal file
View File

@ -0,0 +1,64 @@
# RUN: llc -mtriple=aarch64 -run-pass=patchable-function %s -o - | FileCheck %s
# 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
--- |
define void @empty() #0 !dbg !7 {
entry:
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")
!2 = !{}
!3 = !{i32 7, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = !{i32 1, !"wchar_size", i32 4}
!6 = !{!"clang version 11.0.0 "}
!7 = distinct !DISubprogram(name: "empty", scope: !1, file: !1, line: 1, type: !8, scopeLine: 1, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
!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)
...
---
name: empty
alignment: 4
tracksRegLiveness: true
body: |
bb.0.entry:
liveins: $lr
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
...