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LiveRangeEdit: Fix liveranges not shrinking on subrange kill.

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If a dead instruction we may not only have a last-use in the main live
range but also in a subregister range if subregisters are tracked. We
need to partially rebuild live ranges in both cases.

The testcase only broke when subregister liveness was enabled. I
commited it in the current form because there is currently no flag to
enable/disable subregister liveness.

This fixes PR23720.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238785 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Matthias Braun 2015-06-01 21:26:26 +00:00
parent a3698105eb
commit fa2b7e5cb4
3 changed files with 77 additions and 3 deletions
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4
include/llvm/CodeGen/LiveRangeEdit.h
View File

@ -102,6 +102,10 @@ private:
/// registers are created.
void MRI_NoteNewVirtualRegister(unsigned VReg) override;
/// \brief Check if MachineOperand \p MO is a last use/kill either in the
/// main live range of \p LI or in one of the matching subregister ranges.
bool useIsKill(const LiveInterval &LI, const MachineOperand &MO) const;
public:
/// Create a LiveRangeEdit for breaking down parent into smaller pieces.
/// @param parent The register being spilled or split.

21
lib/CodeGen/LiveRangeEdit.cpp
View File

@ -218,6 +218,22 @@ bool LiveRangeEdit::foldAsLoad(LiveInterval *LI,
return true;
}
bool LiveRangeEdit::useIsKill(const LiveInterval &LI,
const MachineOperand &MO) const {
const MachineInstr *MI = MO.getParent();
SlotIndex Idx = LIS.getInstructionIndex(MI).getRegSlot();
if (LI.Query(Idx).isKill())
return true;
const TargetRegisterInfo &TRI = *MRI.getTargetRegisterInfo();
unsigned SubReg = MO.getSubReg();
unsigned LaneMask = TRI.getSubRegIndexLaneMask(SubReg);
for (const LiveInterval::SubRange &S : LI.subranges()) {
if ((S.LaneMask & LaneMask) != 0 && S.Query(Idx).isKill())
return true;
}
return false;
}
/// Find all live intervals that need to shrink, then remove the instruction.
void LiveRangeEdit::eliminateDeadDef(MachineInstr *MI, ToShrinkSet &ToShrink) {
assert(MI->allDefsAreDead() && "Def isn't really dead");
@ -266,9 +282,8 @@ void LiveRangeEdit::eliminateDeadDef(MachineInstr *MI, ToShrinkSet &ToShrink) {
// unlikely to change anything. We typically don't want to shrink the
// PIC base register that has lots of uses everywhere.
// Always shrink COPY uses that probably come from live range splitting.
if (MI->readsVirtualRegister(Reg) &&
(MI->isCopy() || MOI->isDef() || MRI.hasOneNonDBGUse(Reg) ||
LI.Query(Idx).isKill()))
if ((MI->readsVirtualRegister(Reg) && (MI->isCopy() || MOI->isDef())) ||
(MOI->readsReg() && (MRI.hasOneNonDBGUse(Reg) || useIsKill(LI, *MOI))))
ToShrink.insert(&LI);
// Remove defined value.

55
test/CodeGen/R600/subreg-eliminate-dead.ll Normal file
View File

@ -0,0 +1,55 @@
; RUN: llc -verify-machineinstrs -o - %s | FileCheck %s
; LiveRangeEdit::eliminateDeadDef did not update LiveInterval sub ranges
; properly.
target datalayout = "e-p:32:32-p1:64:64-p2:64:64-p3:32:32-p4:64:64-p5:32:32-p24:64:64-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-v2048:2048-n32:64"
target triple = "amdgcn--"
; CHECK-LABEL: foobar:
; Output with subregister liveness disabled:
; CHECK: v_mov_b32_e32 v1, 1
; CHECK: v_mov_b32_e32 v0, 0
; CHECK: v_cmp_eq_i32_e32 vcc, s0, v0
; CHECK: v_cmp_eq_i32_e64 s[0:1], s0, v1
; CHECK: v_mov_b32_e32 v1, 3
; CHECK: v_mov_b32_e32 v0, 2
; CHECK: v_cmp_eq_i32_e64 s[2:3], s0, v0
; CHECK: v_cmp_eq_i32_e64 s[4:5], s0, v1
; CHECK: v_cndmask_b32_e64 v3, 0, -1, s[4:5]
; CHECK: v_cndmask_b32_e64 v2, 0, -1, s[2:3]
; CHECK: v_cndmask_b32_e64 v1, 0, -1, s[0:1]
; CHECK: v_cndmask_b32_e64 v0, 0, -1, vcc
; CHECK: v_cmp_ne_i32_e32 vcc, 0, v1
; CHECK: v_cndmask_b32_e64 v1, 0, v0, vcc
; CHECK: s_mov_b32 s3, 0xf000
; CHECK: s_mov_b32 s2, -1
; CHECK: buffer_store_dwordx2 v[0:1], s[0:3], 0
; CHECK: s_endpgm
; Output with subregister liveness enabled:
; XCHECK: v_mov_b32_e32 v1, 1
; XCHECK: v_mov_b32_e32 v0, 0
; XCHECK: v_cmp_eq_i32_e32 vcc, s0, v1
; XCHECK: v_mov_b32_e32 v1, 3
; XCHECK: v_mov_b32_e32 v0, 2
; XCHECK: v_cmp_eq_i32_e64 s[0:1], s0, v0
; XCHECK: v_cmp_eq_i32_e64 s[2:3], s0, v1
; XCHECK: v_cndmask_b32_e64 v3, 0, -1, s[2:3]
; XCHECK: v_cndmask_b32_e64 v2, 0, -1, s[0:1]
; XCHECK: v_cndmask_b32_e64 v1, 0, -1, vcc
; XCHECK: v_cmp_ne_i32_e32 vcc, 0, v1
; XCHECK: v_cndmask_b32_e64 v1, 0, v0, vcc
; XCHECK: s_mov_b32 s3, 0xf000
; XCHECK: s_mov_b32 s2, -1
; XCHECK: buffer_store_dwordx2 v[0:1], s[0:3], 0
; XCHECK: s_endpgm
define void @foobar() {
%v0 = icmp eq <4 x i32> undef, <i32 0, i32 1, i32 2, i32 3>
%v3 = sext <4 x i1> %v0 to <4 x i32>
%v4 = extractelement <4 x i32> %v3, i32 1
%v5 = icmp ne i32 %v4, 0
%v6 = select i1 %v5, i32 undef, i32 0
%v15 = insertelement <2 x i32> undef, i32 %v6, i32 1
store <2 x i32> %v15, <2 x i32> addrspace(1)* undef, align 8
ret void
}
declare double @llvm.fma.f64(double, double, double)