[llvm] 1a78b0b - [MachineOutliner] Teach outliner to set live-ins
Eli Friedman via llvm-commits
llvm-commits at lists.llvm.org
Wed Apr 22 14:20:04 PDT 2020
Author: Eli Friedman
Date: 2020-04-22T14:19:26-07:00
New Revision: 1a78b0bd3829381e7be627b459c22083bf4671d4
URL: https://github.com/llvm/llvm-project/commit/1a78b0bd3829381e7be627b459c22083bf4671d4
DIFF: https://github.com/llvm/llvm-project/commit/1a78b0bd3829381e7be627b459c22083bf4671d4.diff
LOG: [MachineOutliner] Teach outliner to set live-ins
Preserving liveness can be useful even late in the pipeline, if we're
doing substantial optimization work afterwards. (See, for example,
D76065.) Teach MachineOutliner how to correctly set live-ins on the
basic block in outlined functions.
Differential Revision: https://reviews.llvm.org/D78605
Added:
Modified:
llvm/lib/CodeGen/MachineOutliner.cpp
llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
llvm/test/CodeGen/AArch64/machine-outliner-calls.mir
llvm/test/CodeGen/AArch64/machine-outliner-retaddr-sign-sp-mod.mir
Removed:
################################################################################
diff --git a/llvm/lib/CodeGen/MachineOutliner.cpp b/llvm/lib/CodeGen/MachineOutliner.cpp
index bd30bd41f07c..e15dcc32c2ba 100644
--- a/llvm/lib/CodeGen/MachineOutliner.cpp
+++ b/llvm/lib/CodeGen/MachineOutliner.cpp
@@ -1178,12 +1178,35 @@ MachineFunction *MachineOutliner::createOutlinedFunction(
MBB.insert(MBB.end(), NewMI);
}
- TII.buildOutlinedFrame(MBB, MF, OF);
-
- // Outlined functions shouldn't preserve liveness.
- MF.getProperties().reset(MachineFunctionProperties::Property::TracksLiveness);
+ // Set normal properties for a late MachineFunction.
+ MF.getProperties().reset(MachineFunctionProperties::Property::IsSSA);
+ MF.getProperties().set(MachineFunctionProperties::Property::NoPHIs);
+ MF.getProperties().set(MachineFunctionProperties::Property::NoVRegs);
+ MF.getProperties().set(MachineFunctionProperties::Property::TracksLiveness);
MF.getRegInfo().freezeReservedRegs(MF);
+ // Compute live-in set for outlined fn
+ const MachineRegisterInfo &MRI = MF.getRegInfo();
+ const TargetRegisterInfo &TRI = *MRI.getTargetRegisterInfo();
+ LivePhysRegs LiveIns(TRI);
+ for (auto &Cand : OF.Candidates) {
+ // Figure out live-ins at the first instruction.
+ MachineBasicBlock &OutlineBB = *Cand.front()->getParent();
+ LivePhysRegs CandLiveIns(TRI);
+ CandLiveIns.addLiveOuts(OutlineBB);
+ for (const MachineInstr &MI :
+ reverse(make_range(Cand.front(), OutlineBB.end())))
+ CandLiveIns.stepBackward(MI);
+
+ // The live-in set for the outlined function is the union of the live-ins
+ // from all the outlining points.
+ for (MCPhysReg Reg : make_range(CandLiveIns.begin(), CandLiveIns.end()))
+ LiveIns.addReg(Reg);
+ }
+ addLiveIns(MBB, LiveIns);
+
+ TII.buildOutlinedFrame(MBB, MF, OF);
+
// If there's a DISubprogram associated with this outlined function, then
// emit debug info for the outlined function.
if (DISubprogram *SP = getSubprogramOrNull(OF)) {
diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
index 25a317f88c7d..564b7c801868 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -6450,7 +6450,8 @@ void AArch64InstrInfo::buildOutlinedFrame(
IsLeafFunction = false;
// LR has to be a live in so that we can save it.
- MBB.addLiveIn(AArch64::LR);
+ if (!MBB.isLiveIn(AArch64::LR))
+ MBB.addLiveIn(AArch64::LR);
MachineBasicBlock::iterator It = MBB.begin();
MachineBasicBlock::iterator Et = MBB.end();
@@ -6529,8 +6530,13 @@ void AArch64InstrInfo::buildOutlinedFrame(
}
// It's not a tail call, so we have to insert the return ourselves.
+
+ // LR has to be a live in so that we can return to it.
+ if (!MBB.isLiveIn(AArch64::LR))
+ MBB.addLiveIn(AArch64::LR);
+
MachineInstr *ret = BuildMI(MF, DebugLoc(), get(AArch64::RET))
- .addReg(AArch64::LR, RegState::Undef);
+ .addReg(AArch64::LR);
MBB.insert(MBB.end(), ret);
signOutlinedFunction(MF, MBB, ShouldSignReturnAddr,
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
index ac8e0ab9ec13..f64e4397dcd3 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
@@ -778,6 +778,8 @@ void RISCVInstrInfo::buildOutlinedFrame(
}
}
+ MBB.addLiveIn(RISCV::X5);
+
// Add in a return instruction to the end of the outlined frame.
MBB.insert(MBB.end(), BuildMI(MF, DebugLoc(), get(RISCV::JALR))
.addReg(RISCV::X0, RegState::Define)
diff --git a/llvm/test/CodeGen/AArch64/machine-outliner-calls.mir b/llvm/test/CodeGen/AArch64/machine-outliner-calls.mir
index 00025ab90625..847ccb927f93 100644
--- a/llvm/test/CodeGen/AArch64/machine-outliner-calls.mir
+++ b/llvm/test/CodeGen/AArch64/machine-outliner-calls.mir
@@ -55,7 +55,8 @@ body: |
RET undef $lr
# CHECK: name: OUTLINED_FUNCTION_0
-# CHECK-DAG: bb.0:
+# CHECK: bb.0:
+# CHECK: liveins: $x19, $x20, $x21, $x22, $x23, $x24, $x25, $x26, $x27, $x28, $d15, $d8, $d9, $d10, $d11, $d12, $d13, $d14, $lr
# CHECK-DAG: frame-setup CFI_INSTRUCTION def_cfa_offset -16
# CHECK-NEXT: frame-setup CFI_INSTRUCTION offset $w30, 16
# CHECK-NEXT: early-clobber $sp = STRXpre $lr, $sp, -16
@@ -63,4 +64,4 @@ body: |
# CHECK-NEXT: $w17 = ORRWri $wzr, 1
# CHECK-NEXT: $w17 = ORRWri $wzr, 1
# CHECK-NEXT: early-clobber $sp, $lr = LDRXpost $sp, 16
-# CHECK-NEXT: RET undef $lr
+# CHECK-NEXT: RET $lr
diff --git a/llvm/test/CodeGen/AArch64/machine-outliner-retaddr-sign-sp-mod.mir b/llvm/test/CodeGen/AArch64/machine-outliner-retaddr-sign-sp-mod.mir
index 0e829776effc..0b86499461bb 100644
--- a/llvm/test/CodeGen/AArch64/machine-outliner-retaddr-sign-sp-mod.mir
+++ b/llvm/test/CodeGen/AArch64/machine-outliner-retaddr-sign-sp-mod.mir
@@ -196,9 +196,11 @@ body: |
# CHECK: name: [[OUTLINED_FUNC]]
# CHECK: body: |
# CHECK-NEXT: bb.0:
+# CHECK-NEXT: liveins: $lr
+# CHECK-NEXT: {{^ $}}
# CHECK-NEXT: frame-setup PACIASP implicit-def $lr, implicit $lr, implicit $sp
# CHECK-NEXT: frame-setup CFI_INSTRUCTION negate_ra_sign_state
# CHECK-NEXT: $sp = frame-setup SUBXri $sp, 16, 0
# CHECK: $sp = frame-destroy ADDXri $sp, 16, 0
# CHECK-NEXT: frame-destroy AUTIASP implicit-def $lr, implicit $lr, implicit $sp
-# CHECK-NEXT: RET undef $lr
+# CHECK-NEXT: RET $lr
More information about the llvm-commits
mailing list