Commit 385d0dd5 authored by David Majnemer's avatar David Majnemer
Browse files

Merging r222856: 

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r222856 | majnemer | 2014-11-26 15:00:38 -0800 (Wed, 26 Nov 2014) | 8 lines

Revert "Added inst combine transforms for single bit tests from Chris's note"

This reverts commit r210006, it miscompiled libapr which is used in who
knows how many projects.

A test has been added to ensure that we don't regress again.

I'll work on a rewrite of what the optimization was trying to do later.
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llvm-svn: 225255
parent 6ad55e92

llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp

+1 −28
Original line number Diff line number Diff line
@@ -387,15 +387,7 @@ static Value *SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp, 
/// 1. The icmp predicate is inverted

/// 2. The select operands are reversed

/// 3. The magnitude of C2 and C1 are flipped

///

/// This also tries to turn

/// --- Single bit tests:

/// if ((x & C) == 0) x |= C	to  x |= C

/// if ((x & C) != 0) x ^= C	to  x &= ~C

/// if ((x & C) == 0) x ^= C	to  x |= C

/// if ((x & C) != 0) x &= ~C	to  x &= ~C

/// if ((x & C) == 0) x &= ~C	to  nothing

static Value *foldSelectICmpAndOr(SelectInst &SI, Value *TrueVal,

static Value *foldSelectICmpAndOr(const SelectInst &SI, Value *TrueVal,

                                  Value *FalseVal,

                                  InstCombiner::BuilderTy *Builder) {

  const ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition());
@@ -414,25 +406,6 @@ static Value *foldSelectICmpAndOr(SelectInst &SI, Value *TrueVal, 
    return nullptr;



  const APInt *C2;

  if (match(TrueVal, m_Specific(X))) {

    // if ((X & C) != 0) X ^= C becomes X &= ~C

    if (match(FalseVal, m_Xor(m_Specific(X), m_APInt(C2))) && C1 == C2)

      return Builder->CreateAnd(X, ~(*C1));

    // if ((X & C) != 0) X &= ~C becomes X &= ~C

    if (match(FalseVal, m_And(m_Specific(X), m_APInt(C2))) && *C1 == ~(*C2))

      return FalseVal;

  } else if (match(FalseVal, m_Specific(X))) {

    // if ((X & C) == 0) X ^= C becomes X |= C

    if (match(TrueVal, m_Xor(m_Specific(X), m_APInt(C2))) && C1 == C2)

      return Builder->CreateOr(X, *C1);

    // if ((X & C) == 0) X &= ~C becomes nothing

    if (match(TrueVal, m_And(m_Specific(X), m_APInt(C2))) && *C1 == ~(*C2))

      return X;

    // if ((X & C) == 0) X |= C becomes X |= C

    if (match(TrueVal, m_Or(m_Specific(X), m_APInt(C2))) && C1 == C2)

      return TrueVal;

  }



  bool OrOnTrueVal = false;

  bool OrOnFalseVal = match(FalseVal, m_Or(m_Specific(TrueVal), m_Power2(C2)));

  if (!OrOnFalseVal)

llvm/test/Transforms/InstCombine/select.ll

+0 −105
Original line number Diff line number Diff line
@@ -996,111 +996,6 @@ define <2 x i32> @select_icmp_eq_and_1_0_or_vector_of_2s(i32 %x, <2 x i32> %y) { 
  ret <2 x i32> %select

}



; CHECK-LABEL: @select_icmp_and_8_eq_0_or_8(

; CHECK-NEXT: [[OR:%[a-z0-9]+]] = or i32 %x, 8

; CHECK-NEXT: ret i32 [[OR]]

define i32 @select_icmp_and_8_eq_0_or_8(i32 %x) {

  %and = and i32 %x, 8

  %cmp = icmp eq i32 %and, 0

  %or = or i32 %x, 8

  %or.x = select i1 %cmp, i32 %or, i32 %x

  ret i32 %or.x

}



; CHECK-LABEL: @select_icmp_and_8_ne_0_xor_8(

; CHECK-NEXT: [[AND:%[a-z0-9]+]] = and i32 %x, -9

; CHECK-NEXT: ret i32 [[AND]]

define i32 @select_icmp_and_8_ne_0_xor_8(i32 %x) {

  %and = and i32 %x, 8

  %cmp = icmp eq i32 %and, 0

  %xor = xor i32 %x, 8

  %x.xor = select i1 %cmp, i32 %x, i32 %xor

  ret i32 %x.xor

}



; CHECK-LABEL: @select_icmp_and_8_eq_0_xor_8(

; CHECK-NEXT: [[OR:%[a-z0-9]+]] = or i32 %x, 8

; CHECK-NEXT: ret i32 [[OR]]

define i32 @select_icmp_and_8_eq_0_xor_8(i32 %x) {

  %and = and i32 %x, 8

  %cmp = icmp eq i32 %and, 0

  %xor = xor i32 %x, 8

  %xor.x = select i1 %cmp, i32 %xor, i32 %x

  ret i32 %xor.x

}



; CHECK-LABEL: @select_icmp_and_8_ne_0_and_not_8(

; CHECK-NEXT: [[AND:%[a-z0-9]+]] = and i32 %x, -9

; CHECK-NEXT: ret i32 [[AND]]

define i32 @select_icmp_and_8_ne_0_and_not_8(i32 %x) {

  %and = and i32 %x, 8

  %cmp = icmp eq i32 %and, 0

  %and1 = and i32 %x, -9

  %x.and1 = select i1 %cmp, i32 %x, i32 %and1

  ret i32 %x.and1

}



; CHECK-LABEL: @select_icmp_and_8_eq_0_and_not_8(

; CHECK-NEXT: ret i32 %x

define i32 @select_icmp_and_8_eq_0_and_not_8(i32 %x) {

  %and = and i32 %x, 8

  %cmp = icmp eq i32 %and, 0

  %and1 = and i32 %x, -9

  %and1.x = select i1 %cmp, i32 %and1, i32 %x

  ret i32 %and1.x

}



; CHECK-LABEL: @select_icmp_x_and_8_eq_0_y_xor_8(

; CHECK: select i1 %cmp, i64 %y, i64 %xor

define i64 @select_icmp_x_and_8_eq_0_y_xor_8(i32 %x, i64 %y) {

  %and = and i32 %x, 8

  %cmp = icmp eq i32 %and, 0

  %xor = xor i64 %y, 8

  %y.xor = select i1 %cmp, i64 %y, i64 %xor

  ret i64 %y.xor

}



; CHECK-LABEL: @select_icmp_x_and_8_eq_0_y_and_not_8(

; CHECK: select i1 %cmp, i64 %y, i64 %and1

define i64 @select_icmp_x_and_8_eq_0_y_and_not_8(i32 %x, i64 %y) {

  %and = and i32 %x, 8

  %cmp = icmp eq i32 %and, 0

  %and1 = and i64 %y, -9

  %y.and1 = select i1 %cmp, i64 %y, i64 %and1

  ret i64 %y.and1

}



; CHECK-LABEL: @select_icmp_x_and_8_ne_0_y_xor_8(

; CHECK: select i1 %cmp, i64 %xor, i64 %y

define i64 @select_icmp_x_and_8_ne_0_y_xor_8(i32 %x, i64 %y) {

  %and = and i32 %x, 8

  %cmp = icmp eq i32 %and, 0

  %xor = xor i64 %y, 8

  %xor.y = select i1 %cmp, i64 %xor, i64 %y

  ret i64 %xor.y

}



; CHECK-LABEL: @select_icmp_x_and_8_ne_0_y_and_not_8(

; CHECK: select i1 %cmp, i64 %and1, i64 %y

define i64 @select_icmp_x_and_8_ne_0_y_and_not_8(i32 %x, i64 %y) {

  %and = and i32 %x, 8

  %cmp = icmp eq i32 %and, 0

  %and1 = and i64 %y, -9

  %and1.y = select i1 %cmp, i64 %and1, i64 %y

  ret i64 %and1.y

}



; CHECK-LABEL: @select_icmp_x_and_8_ne_0_y_or_8(

; CHECK: xor i64 %1, 8

; CHECK: or i64 %2, %y

define i64 @select_icmp_x_and_8_ne_0_y_or_8(i32 %x, i64 %y) {

  %and = and i32 %x, 8

  %cmp = icmp eq i32 %and, 0

  %or = or i64 %y, 8

  %or.y = select i1 %cmp, i64 %or, i64 %y

  ret i64 %or.y

}



define i32 @test65(i64 %x) {

  %1 = and i64 %x, 16

  %2 = icmp ne i64 %1, 0