Revert "Improve handling of COPY instructions with identical value numbers"

This reverts r334594, it breaks buildbots and fails with expensive checks.

llvm-svn: 334598
This commit is contained in:
Krzysztof Parzyszek 2018-06-13 13:49:06 +00:00
parent 8d818cafdb
commit 975a2623d5
2 changed files with 18 additions and 267 deletions

View File

@ -2085,24 +2085,9 @@ class JoinVals {
LaneBitmask computeWriteLanes(const MachineInstr *DefMI, bool &Redef) const;
/// Find the ultimate value that VNI was copied from.
std::tuple<const VNInfo*,unsigned, bool>
followCopyChain(const VNInfo *VNI, unsigned OtherReg) const;
std::pair<const VNInfo*,unsigned> followCopyChain(const VNInfo *VNI) const;
/// Determine whether Val0 for Reg and Val1 for Other.Reg are identical.
/// The first element of the returned pair is true if they are, false
/// otherwise. The second element is true if one value is defined
/// directly via the other, e.g.:
/// %reg0 = ...
/// %regx = COPY %reg0 ;; reg1 defined via reg0
/// %reg1 = COPY %regx ;; val0 == val1
/// -> { true, true }
/// vs
/// %reg0 = COPY %regy
/// %regx = COPY %regy
/// $reg1 = COPY %regx ;; val0 == val1
/// -> { true, false }
std::pair<bool,bool> valuesIdentical(VNInfo *Val0, VNInfo *Val1,
const JoinVals &Other) const;
bool valuesIdentical(VNInfo *Val0, VNInfo *Val1, const JoinVals &Other) const;
/// Analyze ValNo in this live range, and set all fields of Vals[ValNo].
/// Return a conflict resolution when possible, but leave the hard cases as
@ -2218,22 +2203,19 @@ LaneBitmask JoinVals::computeWriteLanes(const MachineInstr *DefMI, bool &Redef)
return L;
}
std::tuple<const VNInfo*, unsigned, bool> JoinVals::followCopyChain(
const VNInfo *VNI, unsigned OtherReg) const {
std::pair<const VNInfo*, unsigned> JoinVals::followCopyChain(
const VNInfo *VNI) const {
unsigned Reg = this->Reg;
bool UsedOtherReg = false;
while (!VNI->isPHIDef()) {
SlotIndex Def = VNI->def;
MachineInstr *MI = Indexes->getInstructionFromIndex(Def);
assert(MI && "No defining instruction");
if (!MI->isFullCopy())
return std::make_tuple(VNI, Reg, UsedOtherReg);
return std::make_pair(VNI, Reg);
unsigned SrcReg = MI->getOperand(1).getReg();
if (SrcReg == OtherReg)
UsedOtherReg = true;
if (!TargetRegisterInfo::isVirtualRegister(SrcReg))
return std::make_tuple(VNI, Reg, UsedOtherReg);
return std::make_pair(VNI, Reg);
const LiveInterval &LI = LIS->getInterval(SrcReg);
const VNInfo *ValueIn;
@ -2259,28 +2241,26 @@ std::tuple<const VNInfo*, unsigned, bool> JoinVals::followCopyChain(
VNI = ValueIn;
Reg = SrcReg;
}
return std::make_tuple(VNI, Reg, UsedOtherReg);
return std::make_pair(VNI, Reg);
}
std::pair<bool,bool> JoinVals::valuesIdentical(VNInfo *Value0, VNInfo *Value1,
const JoinVals &Other) const {
bool JoinVals::valuesIdentical(VNInfo *Value0, VNInfo *Value1,
const JoinVals &Other) const {
const VNInfo *Orig0;
unsigned Reg0;
bool Other0;
std::tie(Orig0, Reg0, Other0) = followCopyChain(Value0, Other.Reg);
if (Orig0 == Value1 && Reg0 == Other.Reg)
return std::make_pair(true, Other0);
std::tie(Orig0, Reg0) = followCopyChain(Value0);
if (Orig0 == Value1)
return true;
const VNInfo *Orig1;
unsigned Reg1;
bool Other1;
std::tie(Orig1, Reg1, Other1) = Other.followCopyChain(Value1, Reg);
std::tie(Orig1, Reg1) = Other.followCopyChain(Value1);
// The values are equal if they are defined at the same place and use the
// same register. Note that we cannot compare VNInfos directly as some of
// them might be from a copy created in mergeSubRangeInto() while the other
// is from the original LiveInterval.
return std::make_pair(Orig0->def == Orig1->def && Reg0 == Reg1, Other1);
return Orig0->def == Orig1->def && Reg0 == Reg1;
}
JoinVals::ConflictResolution
@ -2450,22 +2430,9 @@ JoinVals::analyzeValue(unsigned ValNo, JoinVals &Other) {
// %other = COPY %ext
// %this = COPY %ext <-- Erase this copy
//
// One case to be careful about is a case where the travesal of the
// COPY chain for one register encounters a use of the other register,
// e.g.
// 10 %other = COPY ...
// 20 %x = COPY %other
// 30 %this = COPY %x ;; assume that liveness of %this extends to the
// ;; end of the block (then back to the entry phi)
// Coalescing %this and %other can force a gap in the live range between
// 20r and 30r, and if the COPY at 30 is erased, its liveness will no longer
// extend to the end of the block (an IMPLICIT_DEF may incorrectly be added
// later on to create a definition that is live on exit).
if (DefMI->isFullCopy() && !CP.isPartial()) {
std::pair<bool,bool> P = valuesIdentical(VNI, V.OtherVNI, Other);
if (P.first)
return P.second ? CR_Merge : CR_Erase;
}
if (DefMI->isFullCopy() && !CP.isPartial()
&& valuesIdentical(VNI, V.OtherVNI, Other))
return CR_Erase;
// If the lanes written by this instruction were all undef in OtherVNI, it is
// still safe to join the live ranges. This can't be done with a simple value
@ -2990,8 +2957,7 @@ void RegisterCoalescer::joinSubRegRanges(LiveRange &LRange, LiveRange &RRange,
LRange.join(RRange, LHSVals.getAssignments(), RHSVals.getAssignments(),
NewVNInfo);
LLVM_DEBUG(dbgs() << "\t\tjoined lanes: " << PrintLaneMask(LaneMask) << ' '
<< LRange << "\n");
LLVM_DEBUG(dbgs() << "\t\tjoined lanes: " << LRange << "\n");
if (EndPoints.empty())
return;

View File

@ -1,215 +0,0 @@
# RUN: llc -mtriple=amdgcn--amdpal -mcpu=gfx803 -run-pass=simple-register-coalescing,rename-independent-subregs %s -o - | FileCheck -check-prefix=GCN %s
# This test is for a bug where the following happens:
#
# Inside the loop, %29.sub2 is used in a V_LSHLREV whose result is then used
# in an LDS read. %29 is a 128 bit value that is linked by copies to
# %45 (from phi elimination), %28 (the value in the loop pre-header),
# %31 (defined and subreg-modified in the loop, and used after the loop)
# and %30:
#
# %45:vreg_128 = COPY killed %28
# bb.39:
# %29:vreg_128 = COPY killed %45
# %39:vgpr_32 = V_LSHLREV_B32_e32 2, %29.sub2, implicit $exec
# %31:vreg_128 = COPY killed %29
# %31.sub1:vreg_128 = COPY %34
# %30:vreg_128 = COPY %31
# %45:vreg_128 = COPY killed %30
# S_CBRANCH_EXECNZ %bb.39, implicit $exec
# S_BRANCH %bb.40
# bb.40:
# undef %8615.sub0:vreg_128 = COPY killed %31.sub0
#
# So this coalesces together into a single 128 bit value whose sub1 is modified
# in the loop, but the sub2 used in the V_LSHLREV is not modified in the loop.
#
# The bug is that the coalesced value has a L00000004 subrange (for sub2) that
# says that it is not live up to the end of the loop block. The symptom is that
# Rename Independent Subregs separates sub2 into its own register, and it is
# not live round the loop, so that pass adds an IMPLICIT_DEF for it just before
# the loop backedge.
# GCN: bb.1 (%ir-block.6):
# GCN: V_LSHLREV_B32_e32 2, [[val:%[0-9][0-9]*]].sub2
# GCN-NOT: [[val]]:vreg_128 = IMPLICIT_DEF
--- |
target datalayout = "e-p:64:64-p1:64:64-p2:32:32-p3:32:32-p4:64:64-p5:32:32-p6:32:32-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-v2048:2048-n32:64-S32-A5"
target triple = "amdgcn--amdpal"
define dllexport amdgpu_cs void @_amdgpu_cs_main(i32 inreg, i32 inreg, i32 inreg, <3 x i32> inreg, i32 inreg, <3 x i32>) local_unnamed_addr #0 {
.entry:
br label %6
; <label>:6: ; preds = %6, %.entry
%7 = bitcast i32 addrspace(3)* undef to <2 x i32> addrspace(3)*
%8 = bitcast i32 addrspace(3)* undef to <2 x i32> addrspace(3)*
%9 = bitcast i32 addrspace(3)* undef to <2 x i32> addrspace(3)*
%10 = bitcast i32 addrspace(3)* undef to <2 x i32> addrspace(3)*
%11 = bitcast i32 addrspace(3)* undef to <2 x i32> addrspace(3)*
%12 = bitcast i32 addrspace(3)* undef to <2 x i32> addrspace(3)*
br i1 undef, label %13, label %6
; <label>:13: ; preds = %6
ret void
}
attributes #0 = { "target-cpu"="gfx803" }
...
---
name: _amdgpu_cs_main
alignment: 0
exposesReturnsTwice: false
legalized: false
regBankSelected: false
selected: false
failedISel: false
tracksRegLiveness: true
registers:
- { id: 0, class: sreg_64, preferred-register: '' }
- { id: 1, class: sreg_64, preferred-register: '' }
- { id: 2, class: sreg_64, preferred-register: '' }
- { id: 3, class: sgpr_32, preferred-register: '' }
- { id: 4, class: sgpr_32, preferred-register: '' }
- { id: 5, class: sgpr_32, preferred-register: '' }
- { id: 6, class: sgpr_32, preferred-register: '' }
- { id: 7, class: sreg_32_xm0, preferred-register: '' }
- { id: 8, class: sgpr_32, preferred-register: '' }
- { id: 9, class: sreg_32_xm0, preferred-register: '' }
- { id: 10, class: sreg_32_xm0, preferred-register: '' }
- { id: 11, class: sreg_32_xm0, preferred-register: '' }
- { id: 12, class: vreg_64, preferred-register: '' }
- { id: 13, class: vreg_64, preferred-register: '' }
- { id: 14, class: vreg_64, preferred-register: '' }
- { id: 15, class: vreg_64, preferred-register: '' }
- { id: 16, class: vreg_64, preferred-register: '' }
- { id: 17, class: vreg_64, preferred-register: '' }
- { id: 18, class: sreg_64, preferred-register: '$vcc' }
- { id: 19, class: vreg_128, preferred-register: '' }
- { id: 20, class: vreg_128, preferred-register: '' }
- { id: 21, class: vreg_128, preferred-register: '' }
- { id: 22, class: vreg_128, preferred-register: '' }
- { id: 23, class: vreg_128, preferred-register: '' }
- { id: 24, class: vreg_128, preferred-register: '' }
- { id: 25, class: vreg_128, preferred-register: '' }
- { id: 26, class: vreg_128, preferred-register: '' }
- { id: 27, class: vreg_128, preferred-register: '' }
- { id: 28, class: vreg_128, preferred-register: '' }
- { id: 29, class: vreg_128, preferred-register: '' }
- { id: 30, class: vreg_128, preferred-register: '' }
- { id: 31, class: vreg_128, preferred-register: '' }
- { id: 32, class: vreg_128, preferred-register: '' }
- { id: 33, class: vgpr_32, preferred-register: '' }
- { id: 34, class: sreg_32, preferred-register: '' }
- { id: 35, class: vreg_128, preferred-register: '' }
- { id: 36, class: vreg_128, preferred-register: '' }
- { id: 37, class: vreg_128, preferred-register: '' }
- { id: 38, class: vgpr_32, preferred-register: '' }
- { id: 39, class: vgpr_32, preferred-register: '' }
- { id: 40, class: vgpr_32, preferred-register: '' }
- { id: 41, class: vgpr_32, preferred-register: '' }
- { id: 42, class: vreg_128, preferred-register: '' }
- { id: 43, class: sreg_64, preferred-register: '' }
- { id: 44, class: vreg_128, preferred-register: '' }
- { id: 45, class: vreg_128, preferred-register: '' }
liveins:
frameInfo:
isFrameAddressTaken: false
isReturnAddressTaken: false
hasStackMap: false
hasPatchPoint: false
stackSize: 0
offsetAdjustment: 0
maxAlignment: 0
adjustsStack: false
hasCalls: false
stackProtector: ''
maxCallFrameSize: 4294967295
hasOpaqueSPAdjustment: false
hasVAStart: false
hasMustTailInVarArgFunc: false
localFrameSize: 0
savePoint: ''
restorePoint: ''
fixedStack:
stack:
constants:
body: |
bb.0..entry:
successors: %bb.1(0x80000000)
%3:sgpr_32 = S_MOV_B32 0
undef %19.sub1:vreg_128 = COPY undef %3
dead %4:sgpr_32 = S_MOV_B32 1
%20:vreg_128 = COPY killed %19
%20.sub1:vreg_128 = COPY undef %4
dead %5:sgpr_32 = S_MOV_B32 2
%21:vreg_128 = COPY killed %20
%21.sub1:vreg_128 = COPY undef %5
dead %6:sgpr_32 = S_MOV_B32 3
%22:vreg_128 = COPY killed %21
%22.sub1:vreg_128 = COPY undef %6
dead %7:sreg_32_xm0 = S_MOV_B32 4
%23:vreg_128 = COPY killed %22
%23.sub1:vreg_128 = COPY undef %7
dead %8:sgpr_32 = S_MOV_B32 5
%24:vreg_128 = COPY killed %23
%24.sub1:vreg_128 = COPY undef %8
dead %9:sreg_32_xm0 = S_MOV_B32 6
%25:vreg_128 = COPY killed %24
%25.sub1:vreg_128 = COPY undef %9
dead %10:sreg_32_xm0 = S_MOV_B32 7
%26:vreg_128 = COPY killed %25
%26.sub1:vreg_128 = COPY undef %10
%11:sreg_32_xm0 = S_MOV_B32 255
%27:vreg_128 = COPY killed %26
%27.sub1:vreg_128 = COPY %11
%28:vreg_128 = COPY killed %27
%28.sub2:vreg_128 = COPY killed %11
%2:sreg_64 = S_MOV_B64 0
%34:sreg_32 = S_MOV_B32 7
%37:vreg_128 = COPY undef %42:vreg_128
%43:sreg_64 = COPY killed %2
%44:vreg_128 = COPY killed %37
%45:vreg_128 = COPY killed %28
bb.1 (%ir-block.6):
successors: %bb.2(0x04000000), %bb.1(0x7c000000)
%29:vreg_128 = COPY killed %45
%36:vreg_128 = COPY killed %44
%0:sreg_64 = COPY killed %43
%39:vgpr_32 = V_LSHLREV_B32_e32 2, %29.sub2, implicit $exec
%41:vgpr_32 = V_ADD_I32_e32 1152, %39, implicit-def dead $vcc, implicit $exec
$m0 = S_MOV_B32 -1
%12:vreg_64 = DS_READ2_B32 killed %41, 0, 1, 0, implicit $m0, implicit $exec :: (load 8 from %ir.7, align 4, addrspace 3)
%13:vreg_64 = DS_READ2_B32 %39, -112, -111, 0, implicit $m0, implicit $exec :: (load 8 from %ir.8, align 4, addrspace 3)
%14:vreg_64 = DS_READ2_B32 %39, 0, 1, 0, implicit $m0, implicit $exec :: (load 8 from %ir.9, align 4, addrspace 3)
%40:vgpr_32 = V_ADD_I32_e32 1160, %39, implicit-def dead $vcc, implicit $exec
%15:vreg_64 = DS_READ2_B32 killed %40, 0, 1, 0, implicit $m0, implicit $exec :: (load 8 from %ir.10, align 4, addrspace 3)
%16:vreg_64 = DS_READ2_B32 %39, -110, -109, 0, implicit $m0, implicit $exec :: (load 8 from %ir.11, align 4, addrspace 3)
%17:vreg_64 = DS_READ2_B32 %39, 2, 3, 0, implicit $m0, implicit $exec :: (load 8 from %ir.12, align 4, addrspace 3)
undef %35.sub1:vreg_128 = COPY undef %34
%31:vreg_128 = COPY killed %29
%31.sub1:vreg_128 = COPY %34
%38:vgpr_32 = V_ADD_I32_e32 1, %36.sub0, implicit-def dead $vcc, implicit $exec
%18:sreg_64 = V_CMP_LT_I32_e64 5, %38, implicit $exec
%1:sreg_64 = S_OR_B64 killed %18, killed %0, implicit-def $scc
%30:vreg_128 = COPY %31
%43:sreg_64 = COPY %1
%44:vreg_128 = COPY %35
%45:vreg_128 = COPY killed %30
$exec = S_ANDN2_B64_term $exec, %1
S_CBRANCH_EXECNZ %bb.1, implicit $exec
S_BRANCH %bb.2
bb.2 (%ir-block.13):
$exec = S_OR_B64 $exec, killed %1, implicit-def $scc
%33:vgpr_32 = V_MOV_B32_e32 0, implicit $exec
undef %32.sub0:vreg_128 = COPY killed %31.sub0
%32.sub2:vreg_128 = COPY %33
S_ENDPGM
...