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Back out "Re-land: Teach CorrelatedValuePropagation to reduce the width of udiv/urem instructions."
This reverts r326908, originally landed as D44102. Reverted for causing performance regressions on x86. (These regressions are not yet understood.) llvm-svn: 327252
This commit is contained in:
Justin Lebar
parent
94bcc98a97
commit
32cbf2f15e
@ -58,7 +58,6 @@ STATISTIC(NumCmps, "Number of comparisons propagated");
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STATISTIC(NumReturns, "Number of return values propagated");
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STATISTIC(NumDeadCases, "Number of switch cases removed");
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STATISTIC(NumSDivs, "Number of sdiv converted to udiv");
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STATISTIC(NumUDivs, "Number of udivs whose width was decreased");
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STATISTIC(NumAShrs, "Number of ashr converted to lshr");
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STATISTIC(NumSRems, "Number of srem converted to urem");
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STATISTIC(NumOverflows, "Number of overflow checks removed");
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@ -433,48 +432,6 @@ static bool hasPositiveOperands(BinaryOperator *SDI, LazyValueInfo *LVI) {
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return true;
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}
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/// Try to shrink a udiv/urem's width down to the smallest power of two that's
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/// sufficient to contain its operands.
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static bool processUDivOrURem(BinaryOperator *Instr, LazyValueInfo *LVI) {
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assert(Instr->getOpcode() == Instruction::UDiv ||
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Instr->getOpcode() == Instruction::URem);
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if (Instr->getType()->isVectorTy())
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return false;
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// Find the smallest power of two bitwidth that's sufficient to hold Instr's
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// operands.
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auto OrigWidth = Instr->getType()->getIntegerBitWidth();
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ConstantRange OperandRange(OrigWidth, /*isFullset=*/false);
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for (Value *Operand : Instr->operands()) {
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OperandRange = OperandRange.unionWith(
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LVI->getConstantRange(Operand, Instr->getParent()));
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}
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// Don't shrink below 8 bits wide.
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unsigned NewWidth = std::max<unsigned>(
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PowerOf2Ceil(OperandRange.getUnsignedMax().getActiveBits()), 8);
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// NewWidth might be greater than OrigWidth if OrigWidth is not a power of
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// two.
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if (NewWidth >= OrigWidth)
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return false;
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++NumUDivs;
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auto *TruncTy = Type::getIntNTy(Instr->getContext(), NewWidth);
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auto *LHS = CastInst::Create(Instruction::Trunc, Instr->getOperand(0), TruncTy,
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Instr->getName() + ".lhs.trunc", Instr);
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auto *RHS = CastInst::Create(Instruction::Trunc, Instr->getOperand(1), TruncTy,
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Instr->getName() + ".rhs.trunc", Instr);
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auto *BO =
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BinaryOperator::Create(Instr->getOpcode(), LHS, RHS, Instr->getName(), Instr);
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auto *Zext = CastInst::Create(Instruction::ZExt, BO, Instr->getType(),
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Instr->getName() + ".zext", Instr);
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if (BO->getOpcode() == Instruction::UDiv)
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BO->setIsExact(Instr->isExact());
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Instr->replaceAllUsesWith(Zext);
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Instr->eraseFromParent();
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return true;
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}
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static bool processSRem(BinaryOperator *SDI, LazyValueInfo *LVI) {
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if (SDI->getType()->isVectorTy() || !hasPositiveOperands(SDI, LVI))
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return false;
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@ -484,10 +441,6 @@ static bool processSRem(BinaryOperator *SDI, LazyValueInfo *LVI) {
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SDI->getName(), SDI);
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SDI->replaceAllUsesWith(BO);
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SDI->eraseFromParent();
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// Try to process our new urem.
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processUDivOrURem(BO, LVI);
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return true;
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}
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@ -507,9 +460,6 @@ static bool processSDiv(BinaryOperator *SDI, LazyValueInfo *LVI) {
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SDI->replaceAllUsesWith(BO);
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SDI->eraseFromParent();
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// Try to simplify our new udiv.
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processUDivOrURem(BO, LVI);
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return true;
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}
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@ -645,10 +595,6 @@ static bool runImpl(Function &F, LazyValueInfo *LVI, const SimplifyQuery &SQ) {
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case Instruction::SDiv:
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BBChanged |= processSDiv(cast<BinaryOperator>(II), LVI);
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break;
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case Instruction::UDiv:
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case Instruction::URem:
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BBChanged |= processUDivOrURem(cast<BinaryOperator>(II), LVI);
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break;
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case Instruction::AShr:
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BBChanged |= processAShr(cast<BinaryOperator>(II), LVI);
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break;
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@ -1,95 +0,0 @@
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; RUN: opt < %s -correlated-propagation -S | FileCheck %s
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; CHECK-LABEL: @test_nop
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define void @test_nop(i32 %n) {
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; CHECK udiv i32 %n, 100
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%div = udiv i32 %n, 100
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ret void
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}
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; CHECK-LABEL: @test1(
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define void @test1(i32 %n) {
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entry:
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%cmp = icmp ule i32 %n, 65535
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br i1 %cmp, label %bb, label %exit
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bb:
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; CHECK: udiv i16
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%div = udiv i32 %n, 100
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br label %exit
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exit:
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ret void
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}
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; CHECK-LABEL: @test2(
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define void @test2(i32 %n) {
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entry:
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%cmp = icmp ule i32 %n, 65536
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br i1 %cmp, label %bb, label %exit
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bb:
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; CHECK: udiv i32 %n, 100
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%div = udiv i32 %n, 100
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br label %exit
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exit:
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ret void
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}
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; CHECK-LABEL: @test3(
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define void @test3(i32 %m, i32 %n) {
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entry:
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%cmp1 = icmp ult i32 %m, 65535
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%cmp2 = icmp ult i32 %n, 65535
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%cmp = and i1 %cmp1, %cmp2
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br i1 %cmp, label %bb, label %exit
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bb:
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; CHECK: udiv i16
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%div = udiv i32 %m, %n
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br label %exit
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exit:
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ret void
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}
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; CHECK-LABEL: @test4(
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define void @test4(i32 %m, i32 %n) {
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entry:
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%cmp1 = icmp ult i32 %m, 65535
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%cmp2 = icmp ule i32 %n, 65536
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%cmp = and i1 %cmp1, %cmp2
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br i1 %cmp, label %bb, label %exit
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bb:
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; CHECK: udiv i32 %m, %n
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%div = udiv i32 %m, %n
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br label %exit
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exit:
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ret void
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}
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; CHECK-LABEL: @test5
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define void @test5(i32 %n) {
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%trunc = and i32 %n, 65535
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; CHECK: udiv i16
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%div = udiv i32 %trunc, 42
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ret void
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}
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; CHECK-LABEL: @test6
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define void @test6(i32 %n) {
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entry:
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%cmp = icmp ule i32 %n, 255
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br i1 %cmp, label %bb, label %exit
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bb:
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; CHECK: udiv i8
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%div = sdiv i32 %n, 100
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br label %exit
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exit:
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ret void
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}
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@ -1,101 +0,0 @@
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; RUN: opt < %s -correlated-propagation -S | FileCheck %s
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; CHECK-LABEL: @test_nop
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define void @test_nop(i32 %n) {
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; CHECK udiv i32 %n, 100
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%div = udiv i32 %n, 100
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ret void
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}
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; CHECK-LABEL: @test1(
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define void @test1(i32 %n) {
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entry:
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%cmp = icmp ule i32 %n, 65535
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br i1 %cmp, label %bb, label %exit
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bb:
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; CHECK: urem i16
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%div = urem i32 %n, 100
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br label %exit
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exit:
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ret void
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}
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; CHECK-LABEL: @test2(
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define void @test2(i32 %n) {
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entry:
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%cmp = icmp ule i32 %n, 65536
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br i1 %cmp, label %bb, label %exit
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bb:
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; CHECK: urem i32 %n, 100
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%div = urem i32 %n, 100
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br label %exit
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exit:
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ret void
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}
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; CHECK-LABEL: @test3(
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define void @test3(i32 %m, i32 %n) {
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entry:
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%cmp1 = icmp ult i32 %m, 65535
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%cmp2 = icmp ult i32 %n, 65535
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%cmp = and i1 %cmp1, %cmp2
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br i1 %cmp, label %bb, label %exit
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bb:
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; CHECK: urem i16
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%div = urem i32 %m, %n
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br label %exit
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exit:
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ret void
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}
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; CHECK-LABEL: @test4(
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define void @test4(i32 %m, i32 %n) {
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entry:
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%cmp1 = icmp ult i32 %m, 65535
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%cmp2 = icmp ule i32 %n, 65536
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%cmp = and i1 %cmp1, %cmp2
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br i1 %cmp, label %bb, label %exit
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bb:
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; CHECK: urem i32 %m, %n
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%div = urem i32 %m, %n
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br label %exit
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exit:
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ret void
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}
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; CHECK-LABEL: @test5
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define void @test5(i32 %n) {
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%trunc = and i32 %n, 63
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; CHECK: urem i8
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%div = urem i32 %trunc, 42
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ret void
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}
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; CHECK-LABEL: @test6
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define void @test6(i32 %n) {
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entry:
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%cmp = icmp ule i32 %n, 255
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br i1 %cmp, label %bb, label %exit
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bb:
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; CHECK: urem i8
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%div = srem i32 %n, 100
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br label %exit
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exit:
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ret void
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}
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; CHECK-LABEL: @non_power_of_2
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define void @non_power_of_2(i24 %n) {
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%div = urem i24 %n, 42
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ret void
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}
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