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Revert "[Thumb] Teach ISel how to lower compares of AND bitmasks efficiently"

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This reverts commit r281323. It caused chromium test failures and a selfhost failure.

llvm-svn: 281451
This commit is contained in:
James Molloy 2016-09-14 09:45:28 +00:00
parent 696a87c99c
commit 69a6bea0ca
9 changed files with 26 additions and 231 deletions
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6
lib/Target/ARM/ARMBaseInstrInfo.cpp
View File

@ -2528,11 +2528,7 @@ bool ARMBaseInstrInfo::optimizeCompareInstr(
case ARM::EORrr:
case ARM::EORri:
case ARM::t2EORrr:
case ARM::t2EORri:
case ARM::t2LSRri:
case ARM::t2LSRrr:
case ARM::t2LSLri:
case ARM::t2LSLrr: {
case ARM::t2EORri: {
// Scan forward for the use of CPSR
// When checking against MI: if it's a conditional code that requires
// checking of the V bit or C bit, then this is not safe to do.

137
lib/Target/ARM/ARMISelDAGToDAG.cpp
View File

@ -244,8 +244,7 @@ private:
bool tryInlineAsm(SDNode *N);
void SelectConcatVector(SDNode *N);
void SelectCMPZ(SDNode *N, bool &SwitchEQNEToPLMI);
bool trySMLAWSMULW(SDNode *N);
void SelectCMP_SWAP(SDNode *N);
@ -2694,83 +2693,6 @@ void ARMDAGToDAGISel::SelectConcatVector(SDNode *N) {
ReplaceNode(N, createDRegPairNode(VT, N->getOperand(0), N->getOperand(1)));
}
static Optional<std::pair<unsigned, unsigned>>
getContiguousRangeOfSetBits(const APInt &A) {
unsigned FirstOne = A.getBitWidth() - A.countLeadingZeros() - 1;
unsigned LastOne = A.countTrailingZeros();
if (A.countPopulation() != (FirstOne - LastOne + 1))
return Optional<std::pair<unsigned,unsigned>>();
return std::make_pair(FirstOne, LastOne);
}
void ARMDAGToDAGISel::SelectCMPZ(SDNode *N, bool &SwitchEQNEToPLMI) {
assert(N->getOpcode() == ARMISD::CMPZ);
SwitchEQNEToPLMI = false;
if (!Subtarget->isThumb())
// FIXME: Work out whether it is profitable to do this in A32 mode - LSL and
// LSR don't exist as standalone instructions - they need the barrel shifter.
return;
// select (cmpz (and X, C), #0) -> (LSLS X) or (LSRS X) or (LSRS (LSLS X))
SDValue And = N->getOperand(0);
SDValue Zero = N->getOperand(1);
if (!isa<ConstantSDNode>(Zero) || !cast<ConstantSDNode>(Zero)->isNullValue() ||
And->getOpcode() != ISD::AND)
return;
SDValue X = And.getOperand(0);
auto C = dyn_cast<ConstantSDNode>(And.getOperand(1));
if (!C || !X->hasOneUse())
return;
auto Range = getContiguousRangeOfSetBits(C->getAPIntValue());
if (!Range)
return;
// There are several ways to lower this:
SDNode *NewN;
SDLoc dl(N);
auto EmitShift = [&](unsigned Opc, SDValue Src, unsigned Imm) -> SDNode* {
if (Subtarget->isThumb2()) {
Opc = (Opc == ARM::tLSLri) ? ARM::t2LSLri : ARM::t2LSRri;
SDValue Ops[] = { Src, CurDAG->getTargetConstant(Imm, dl, MVT::i32),
getAL(CurDAG, dl), CurDAG->getRegister(0, MVT::i32),
CurDAG->getRegister(0, MVT::i32) };
return CurDAG->getMachineNode(Opc, dl, MVT::i32, Ops);
} else {
SDValue Ops[] = {CurDAG->getRegister(ARM::CPSR, MVT::i32), Src,
CurDAG->getTargetConstant(Imm, dl, MVT::i32),
getAL(CurDAG, dl), CurDAG->getRegister(0, MVT::i32)};
return CurDAG->getMachineNode(Opc, dl, MVT::i32, Ops);
}
};
if (Range->second == 0) {
// 1. Mask includes the LSB -> Simply shift the top N bits off
NewN = EmitShift(ARM::tLSLri, X, 31 - Range->first);
ReplaceNode(And.getNode(), NewN);
} else if (Range->first == 31) {
// 2. Mask includes the MSB -> Simply shift the bottom N bits off
NewN = EmitShift(ARM::tLSRri, X, Range->second);
ReplaceNode(And.getNode(), NewN);
} else if (Range->first == Range->second) {
// 3. Only one bit is set. We can shift this into the sign bit and use a
// PL/MI comparison.
NewN = EmitShift(ARM::tLSLri, X, 31 - Range->first);
ReplaceNode(And.getNode(), NewN);
SwitchEQNEToPLMI = true;
} else if (!Subtarget->hasV6T2Ops()) {
// 4. Do a double shift to clear bottom and top bits, but only in
// thumb-1 mode as in thumb-2 we can use UBFX.
NewN = EmitShift(ARM::tLSLri, X, 31 - Range->first);
NewN = EmitShift(ARM::tLSRri, SDValue(NewN, 0),
Range->second + (31 - Range->first));
ReplaceNode(And.getNode(), NewN);
}
}
void ARMDAGToDAGISel::Select(SDNode *N) {
SDLoc dl(N);
@ -2998,7 +2920,6 @@ void ARMDAGToDAGISel::Select(SDNode *N) {
return;
}
}
break;
}
case ARMISD::VMOVRRD:
@ -3189,27 +3110,9 @@ void ARMDAGToDAGISel::Select(SDNode *N) {
assert(N2.getOpcode() == ISD::Constant);
assert(N3.getOpcode() == ISD::Register);
unsigned CC = (unsigned) cast<ConstantSDNode>(N2)->getZExtValue();
if (InFlag.getOpcode() == ARMISD::CMPZ) {
bool SwitchEQNEToPLMI;
SelectCMPZ(InFlag.getNode(), SwitchEQNEToPLMI);
InFlag = N->getOperand(4);
if (SwitchEQNEToPLMI) {
switch ((ARMCC::CondCodes)CC) {
default: llvm_unreachable("CMPZ must be either NE or EQ!");
case ARMCC::NE:
CC = (unsigned)ARMCC::MI;
break;
case ARMCC::EQ:
CC = (unsigned)ARMCC::PL;
break;
}
}
}
SDValue Tmp2 = CurDAG->getTargetConstant(CC, dl, MVT::i32);
SDValue Tmp2 = CurDAG->getTargetConstant(((unsigned)
cast<ConstantSDNode>(N2)->getZExtValue()), dl,
MVT::i32);
SDValue Ops[] = { N1, Tmp2, N3, Chain, InFlag };
SDNode *ResNode = CurDAG->getMachineNode(Opc, dl, MVT::Other,
MVT::Glue, Ops);
@ -3264,38 +3167,6 @@ void ARMDAGToDAGISel::Select(SDNode *N) {
// Other cases are autogenerated.
break;
}
case ARMISD::CMOV: {
SDValue InFlag = N->getOperand(4);
if (InFlag.getOpcode() == ARMISD::CMPZ) {
bool SwitchEQNEToPLMI;
SelectCMPZ(InFlag.getNode(), SwitchEQNEToPLMI);
if (SwitchEQNEToPLMI) {
SDValue ARMcc = N->getOperand(2);
ARMCC::CondCodes CC =
(ARMCC::CondCodes)cast<ConstantSDNode>(ARMcc)->getZExtValue();
switch (CC) {
default: llvm_unreachable("CMPZ must be either NE or EQ!");
case ARMCC::NE:
CC = ARMCC::MI;
break;
case ARMCC::EQ:
CC = ARMCC::PL;
break;
}
SDValue NewARMcc = CurDAG->getConstant((unsigned)CC, dl, MVT::i32);
SDValue Ops[] = {N->getOperand(0), N->getOperand(1), NewARMcc,
N->getOperand(3), N->getOperand(4)};
CurDAG->MorphNodeTo(N, ARMISD::CMOV, N->getVTList(), Ops);
}
}
// Other cases are autogenerated.
break;
}
case ARMISD::VZIP: {
unsigned Opc = 0;

71
test/CodeGen/ARM/and-cmpz.ll
View File

@ -1,71 +0,0 @@
; RUN: llc -mtriple=thumbv7m-linux-gnu < %s | FileCheck %s --check-prefix=CHECK --check-prefix=T2
; RUN: llc -mtriple=thumbv6m-linux-gnu < %s | FileCheck %s --check-prefix=CHECK --check-prefix=T1
; CHECK-LABEL: single_bit:
; CHECK: lsls r0, r0, #23
; T2-NEXT: mov
; T2-NEXT: it
; T1-NEXT: bmi
define i32 @single_bit(i32 %p) {
%a = and i32 %p, 256
%b = icmp eq i32 %a, 0
br i1 %b, label %true, label %false
true:
ret i32 1
false:
ret i32 2
}
; CHECK-LABEL: multi_bit_lsb_ubfx:
; CHECK: lsls r0, r0, #24
; T2-NEXT: mov
; T2-NEXT: it
; T1-NEXT: beq
define i32 @multi_bit_lsb_ubfx(i32 %p) {
%a = and i32 %p, 255
%b = icmp eq i32 %a, 0
br i1 %b, label %true, label %false
true:
ret i32 1
false:
ret i32 2
}
; CHECK-LABEL: multi_bit_msb:
; CHECK: lsrs r0, r0, #24
; T2-NEXT: mov
; T2-NEXT: it
; T1-NEXT: beq
define i32 @multi_bit_msb(i32 %p) {
%a = and i32 %p, 4278190080 ; 0xff000000
%b = icmp eq i32 %a, 0
br i1 %b, label %true, label %false
true:
ret i32 1
false:
ret i32 2
}
; CHECK-LABEL: multi_bit_nosb:
; T1: lsls r0, r0, #8
; T1-NEXT: lsrs r0, r0, #24
; T2: tst.w
; T2-NEXT: it
; T1-NEXT: beq
define i32 @multi_bit_nosb(i32 %p) {
%a = and i32 %p, 16711680 ; 0x00ff0000
%b = icmp eq i32 %a, 0
br i1 %b, label %true, label %false
true:
ret i32 1
false:
ret i32 2
}

15
test/CodeGen/ARM/arm-and-tst-peephole.ll
View File

@ -28,10 +28,12 @@ tailrecurse: ; preds = %sw.bb, %entry
; ARM: ands {{r[0-9]+}}, {{r[0-9]+}}, #3
; ARM-NEXT: beq
; THUMB: lsls r[[R0:[0-9]+]], r{{.*}}, #30
; THUMB: movs r[[R0:[0-9]+]], #3
; THUMB-NEXT: ands r[[R0]], r
; THUMB-NEXT: cmp r[[R0]], #0
; THUMB-NEXT: beq
; T2: lsls r[[R0:[0-9]+]], r{{.*}}, #30
; T2: ands {{r[0-9]+}}, {{r[0-9]+}}, #3
; T2-NEXT: beq
%and = and i32 %0, 3
@ -91,7 +93,7 @@ entry:
%1 = load i8, i8* %0, align 1
%2 = zext i8 %1 to i32
; ARM: ands
; THUMB: lsls
; THUMB: ands
; T2: ands
; V8: ands
; V8-NEXT: beq
@ -148,9 +150,10 @@ define i32 @test_tst_assessment(i1 %lhs, i1 %rhs) {
%rhs32 = zext i1 %rhs to i32
%diff = sub nsw i32 %lhs32, %rhs32
; ARM: tst r1, #1
; THUMB: lsls r1, r1, #31
; T2: lsls r1, r1, #31
; V8: lsls r1, r1, #31
; THUMB: movs [[RTMP:r[0-9]+]], #1
; THUMB: tst r1, [[RTMP]]
; T2: tst.w r1, #1
; V8: tst.w r1, #1
ret i32 %diff
}

4
test/CodeGen/ARM/arm-shrink-wrapping.ll
View File

@ -638,12 +638,12 @@ declare double @llvm.pow.f64(double, double)
; during PEI with shrink-wrapping enable.
; CHECK-LABEL: debug_info:
;
; ENABLE: {{tst r2, #1|lsls r1, r2, #31}}
; ENABLE: tst{{(\.w)?}} r2, #1
; ENABLE-NEXT: beq [[BB13:LBB[0-9_]+]]
;
; CHECK: push
;
; DISABLE: {{tst r2, #1|lsls r1, r2, #31}}
; DISABLE: tst{{(\.w)?}} r2, #1
; DISABLE-NEXT: beq [[BB13:LBB[0-9_]+]]
;
; CHECK: bl{{x?}} _pow

2
test/CodeGen/ARM/call-tc.ll
View File

@ -120,7 +120,7 @@ if.end: ; preds = %entry
br i1 %tobool2, label %if.end5, label %if.then3
if.then3: ; preds = %if.end
; CHECKT2D: bmi.w _b
; CHECKT2D: bne.w _b
%call4 = tail call i32 @b(i32 %x) nounwind
br label %return

2
test/CodeGen/ARM/debug-info-branch-folding.ll
View File

@ -3,7 +3,7 @@ target datalayout = "e-p:32:32:32-i1:8:32-i8:8:32-i16:16:32-i32:32:32-i64:32:32-
target triple = "thumbv7-apple-macosx10.6.7"
;CHECK: vadd.f32 q4, q8, q8
;CHECK-NEXT: Ltmp
;CHECK-NEXT: Ltmp1
;CHECK-NEXT: LBB0_1
;CHECK:@DEBUG_VALUE: x <- %Q4{{$}}

8
test/CodeGen/Thumb/thumb-shrink-wrapping.ll
View File

@ -650,14 +650,11 @@ define i1 @beq_to_bx(i32* %y, i32 %head) {
; CHECK: tst r3, r4
; ENABLE-NEXT: pop {r4}
; ENABLE-NEXT: mov r12, r{{.*}}
; ENABLE-NEXT: pop {r0}
; ENABLE-NEXT: mov lr, r0
; ENABLE-NEXT: mov r0, r12
; ENABLE-NEXT: pop {r3}
; ENABLE-NEXT: mov lr, r3
; CHECK-NEXT: beq [[EXIT_LABEL]]
; CHECK: str r1, [r2]
; CHECK: str r3, [r2]
; CHECK-NEXT: movs r0, #0
; CHECK-NEXT: [[EXIT_LABEL]]: @ %cleanup
; ENABLE-NEXT: bx lr
@ -678,7 +675,6 @@ if.end:
if.end4:
store i32 %head, i32* %y, align 4
store volatile i32 %z, i32* %y, align 4
br label %cleanup
cleanup:

12
test/CodeGen/Thumb2/float-ops.ll
View File

@ -259,9 +259,9 @@ define i64 @bitcast_d_to_i(double %a) {
define float @select_f(float %a, float %b, i1 %c) {
; CHECK-LABEL: select_f:
; NONE: lsls r2, r2, #31
; NONE: tst.w r2, #1
; NONE: moveq r0, r1
; HARD: lsls r0, r0, #31
; HARD: tst.w r0, #1
; VFP4-ALL: vmovne.f32 s1, s0
; VFP4-ALL: vmov.f32 s0, s1
; FP-ARMv8: vseleq.f32 s0, s1, s0
@ -271,18 +271,18 @@ define float @select_f(float %a, float %b, i1 %c) {
define double @select_d(double %a, double %b, i1 %c) {
; CHECK-LABEL: select_d:
; NONE: ldr{{(.w)?}} [[REG:r[0-9]+]], [sp]
; NONE: lsls{{(.w)?}} [[REG]], [[REG]], #31
; NONE: ldr.w [[REG:r[0-9]+]], [sp]
; NONE: ands [[REG]], [[REG]], #1
; NONE: moveq r0, r2
; NONE: moveq r1, r3
; SP: lsls r0, r0, #31
; SP: ands r0, r0, #1
; SP-DAG: vmov [[ALO:r[0-9]+]], [[AHI:r[0-9]+]], d0
; SP-DAG: vmov [[BLO:r[0-9]+]], [[BHI:r[0-9]+]], d1
; SP: itt ne
; SP-DAG: movne [[BLO]], [[ALO]]
; SP-DAG: movne [[BHI]], [[AHI]]
; SP: vmov d0, [[BLO]], [[BHI]]
; DP: lsls r0, r0, #31
; DP: tst.w r0, #1
; VFP4-DP: vmovne.f64 d1, d0
; VFP4-DP: vmov.f64 d0, d1
; FP-ARMV8: vseleq.f64 d0, d1, d0