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[MachineOutliner] Don't outline functions starting with PATCHABLE_FUNCTION_ENTER/FENTRL_CALL

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MachineOutliner may outline a "patchable-function-entry" function whose body has
a TargetOpcode::PATCHABLE_FUNCTION_ENTER MachineInstr. This is incorrect because
the special code sequence must stay unchanged to be used at run-time.
Avoid outlining PATCHABLE_FUNCTION_ENTER. While here, avoid outlining FENTRY_CALL too
(which doesn't reproduce currently) to allow phase ordering flexibility.

Fixes #52635

Reviewed By: paquette

Differential Revision: https://reviews.llvm.org/D115614

(cherry picked from commit a6a07a514b)
This commit is contained in:
Fangrui Song 2021-12-13 13:24:29 -08:00 committed by Tom Stellard
parent 69fcfdedc5
commit 0d44201451
6 changed files with 208 additions and 4 deletions
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4
llvm/include/llvm/CodeGen/TargetInstrInfo.h
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@ -1922,9 +1922,7 @@ public:
/// Optional target hook that returns true if \p MBB is safe to outline from,
/// and returns any target-specific information in \p Flags.
virtual bool isMBBSafeToOutlineFrom(MachineBasicBlock &MBB,
unsigned &Flags) const {
return true;
}
unsigned &Flags) const;
/// Insert a custom frame for outlined functions.
virtual void buildOutlinedFrame(MachineBasicBlock &MBB, MachineFunction &MF,

13
llvm/lib/CodeGen/TargetInstrInfo.cpp
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@ -1417,3 +1417,16 @@ std::string TargetInstrInfo::createMIROperandComment(
}
TargetInstrInfo::PipelinerLoopInfo::~PipelinerLoopInfo() {}
bool TargetInstrInfo::isMBBSafeToOutlineFrom(MachineBasicBlock &MBB,
unsigned &Flags) const {
// Some instrumentations create special TargetOpcode at the start which
// expands to special code sequences which must be present.
auto First = MBB.getFirstNonDebugInstr();
if (First != MBB.end() &&
(First->getOpcode() == TargetOpcode::FENTRY_CALL ||
First->getOpcode() == TargetOpcode::PATCHABLE_FUNCTION_ENTER))
return false;
return true;
}

2
llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
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@ -6923,6 +6923,8 @@ bool AArch64InstrInfo::isFunctionSafeToOutlineFrom(
bool AArch64InstrInfo::isMBBSafeToOutlineFrom(MachineBasicBlock &MBB,
unsigned &Flags) const {
if (!TargetInstrInfo::isMBBSafeToOutlineFrom(MBB, Flags))
return false;
// Check if LR is available through all of the MBB. If it's not, then set
// a flag.
assert(MBB.getParent()->getRegInfo().tracksLiveness() &&

2
llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
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@ -999,7 +999,7 @@ bool RISCVInstrInfo::isFunctionSafeToOutlineFrom(
bool RISCVInstrInfo::isMBBSafeToOutlineFrom(MachineBasicBlock &MBB,
unsigned &Flags) const {
// More accurate safety checking is done in getOutliningCandidateInfo.
return true;
return TargetInstrInfo::isMBBSafeToOutlineFrom(MBB, Flags);
}
// Enum values indicating how an outlined call should be constructed.

114
llvm/test/CodeGen/AArch64/machine-outliner-patchable.ll Normal file
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@ -0,0 +1,114 @@
; RUN: llc < %s -verify-machineinstrs -enable-machine-outliner | FileCheck %s
target triple = "aarch64-unknown-linux-gnu"
declare void @foo(i32, i32, i32, i32) minsize
;; TargetOpcode::FENTRY_CALL at the start of the function expands to a __fentry__
;; call which must be present. Don't outline it.
define void @fentry0(i1 %a) nounwind "fentry-call"="true" {
; CHECK-LABEL: fentry0:
; CHECK-NEXT: // %bb.0:
; CHECK-NEXT: # FEntry call
; CHECK: // %bb.1:
; CHECK-NEXT: bl OUTLINED_FUNCTION_1
entry:
br i1 %a, label %if.then, label %if.end
if.then:
call void @foo(i32 1, i32 2, i32 3, i32 4)
br label %if.end
if.end:
call void @foo(i32 5, i32 6, i32 7, i32 8)
ret void
}
define void @fentry1(i1 %a) nounwind "fentry-call"="true" {
; CHECK-LABEL: fentry1:
; CHECK-NEXT: // %bb.0:
; CHECK-NEXT: # FEntry call
; CHECK: // %bb.1:
; CHECK-NEXT: bl OUTLINED_FUNCTION_1
entry:
br i1 %a, label %if.then, label %if.end
if.then:
call void @foo(i32 1, i32 2, i32 3, i32 4)
br label %if.end
if.end:
call void @foo(i32 5, i32 6, i32 7, i32 8)
ret void
}
;; TargetOpcode::PATCHABLE_FUNCTION_ENTER at the start of the function expands to
;; NOPs which must be present. Don't outline them.
define void @patchable0(i1 %a) nounwind "patchable-function-entry"="2" {
; CHECK-LABEL: patchable0:
; CHECK-NEXT: .Lfunc_begin0:
; CHECK-NEXT: // %bb.0:
; CHECK-NEXT: nop
; CHECK-NEXT: nop
; CHECK: // %bb.1:
; CHECK-NEXT: bl OUTLINED_FUNCTION_1
entry:
br i1 %a, label %if.then, label %if.end
if.then:
call void @foo(i32 1, i32 2, i32 3, i32 4)
br label %if.end
if.end:
call void @foo(i32 5, i32 6, i32 7, i32 8)
ret void
}
define void @patchable1(i1 %a) nounwind "patchable-function-entry"="2" {
; CHECK-LABEL: patchable1:
; CHECK-NEXT: .Lfunc_begin1:
; CHECK-NEXT: // %bb.0:
; CHECK-NEXT: nop
; CHECK-NEXT: nop
; CHECK: // %bb.1:
; CHECK-NEXT: bl OUTLINED_FUNCTION_1
entry:
br i1 %a, label %if.then, label %if.end
if.then:
call void @foo(i32 1, i32 2, i32 3, i32 4)
br label %if.end
if.end:
call void @foo(i32 5, i32 6, i32 7, i32 8)
ret void
}
;; Similar to "patchable-function-entry".
define void @xray0(i1 %a) nounwind "function-instrument"="xray-always" {
; CHECK-LABEL: xray0:
; CHECK-NEXT: .Lfunc_begin2:
; CHECK-NEXT: // %bb.0:
; CHECK-NEXT: .p2align 2
; CHECK-NEXT: .Lxray_sled_0:
; CHECK: // %bb.1:
; CHECK-NEXT: bl OUTLINED_FUNCTION_1
entry:
br i1 %a, label %if.then, label %if.end
if.then:
call void @foo(i32 1, i32 2, i32 3, i32 4)
br label %if.end
if.end:
call void @foo(i32 5, i32 6, i32 7, i32 8)
ret void
}
define void @xray1(i1 %a) nounwind "function-instrument"="xray-always" {
; CHECK-LABEL: xray1:
; CHECK-NEXT: .Lfunc_begin3:
; CHECK-NEXT: // %bb.0:
; CHECK-NEXT: .p2align 2
; CHECK-NEXT: .Lxray_sled_2:
; CHECK: // %bb.1:
; CHECK-NEXT: bl OUTLINED_FUNCTION_1
entry:
br i1 %a, label %if.then, label %if.end
if.then:
call void @foo(i32 1, i32 2, i32 3, i32 4)
br label %if.end
if.end:
call void @foo(i32 5, i32 6, i32 7, i32 8)
ret void
}

77
llvm/test/CodeGen/RISCV/machine-outliner-patchable.ll Normal file
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@ -0,0 +1,77 @@
; RUN: llc < %s -verify-machineinstrs -enable-machine-outliner | FileCheck %s
target triple = "riscv64-unknown-linux-gnu"
declare void @foo(i32, i32, i32, i32) minsize
;; TargetOpcode::FENTRY_CALL at the start of the function expands to a __fentry__
;; call which must be present. Don't outline it.
define void @fentry0(i1 %a) nounwind "fentry-call"="true" {
; CHECK-LABEL: fentry0:
; CHECK-NEXT: # %bb.0:
; CHECK-NEXT: # FEntry call
; CHECK: # %bb.1:
; CHECK-NEXT: call t0, OUTLINED_FUNCTION_1
entry:
br i1 %a, label %if.then, label %if.end
if.then:
call void @foo(i32 1, i32 2, i32 3, i32 4)
br label %if.end
if.end:
call void @foo(i32 5, i32 6, i32 7, i32 8)
ret void
}
define void @fentry1(i1 %a) nounwind "fentry-call"="true" {
; CHECK-LABEL: fentry1:
; CHECK-NEXT: # %bb.0:
; CHECK-NEXT: # FEntry call
; CHECK: # %bb.1:
; CHECK-NEXT: call t0, OUTLINED_FUNCTION_1
entry:
br i1 %a, label %if.then, label %if.end
if.then:
call void @foo(i32 1, i32 2, i32 3, i32 4)
br label %if.end
if.end:
call void @foo(i32 5, i32 6, i32 7, i32 8)
ret void
}
;; TargetOpcode::PATCHABLE_FUNCTION_ENTER at the start of the function expands to
;; NOPs which must be present. Don't outline them.
define void @patchable0(i1 %a) nounwind "patchable-function-entry"="2" {
; CHECK-LABEL: patchable0:
; CHECK-NEXT: .Lfunc_begin0:
; CHECK-NEXT: # %bb.0:
; CHECK-NEXT: nop
; CHECK-NEXT: nop
; CHECK: # %bb.1:
; CHECK-NEXT: call t0, OUTLINED_FUNCTION_1
entry:
br i1 %a, label %if.then, label %if.end
if.then:
call void @foo(i32 1, i32 2, i32 3, i32 4)
br label %if.end
if.end:
call void @foo(i32 5, i32 6, i32 7, i32 8)
ret void
}
define void @patchable1(i1 %a) nounwind "patchable-function-entry"="2" {
; CHECK-LABEL: patchable1:
; CHECK-NEXT: .Lfunc_begin1:
; CHECK-NEXT: # %bb.0:
; CHECK-NEXT: nop
; CHECK-NEXT: nop
; CHECK: # %bb.1:
; CHECK-NEXT: call t0, OUTLINED_FUNCTION_1
entry:
br i1 %a, label %if.then, label %if.end
if.then:
call void @foo(i32 1, i32 2, i32 3, i32 4)
br label %if.end
if.end:
call void @foo(i32 5, i32 6, i32 7, i32 8)
ret void
}