Unverified Commit 1badf7c3 authored by Roman Lebedev's avatar Roman Lebedev
Browse files

[InstComine] Forego of one-use check in `(X - (X & Y)) --> (X & ~Y)` if Y is a constant 

Summary:
This is potentially more friendly for further optimizations,
analysies, e.g.: https://godbolt.org/z/G24anE

This resolves phase-ordering bug that was introduced
in D75145 for https://godbolt.org/z/2gBwF2
https://godbolt.org/z/XvgSua

Reviewers: spatel, nikic, dmgreen, xbolva00

Reviewed By: nikic, xbolva00

Subscribers: hiraditya, zzheng, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D75757
parent dcf6494a

llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp

+6 −5
Original line number Diff line number Diff line
@@ -1917,6 +1917,12 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) { 
      return NewSel;

  }



  // (X - (X & Y))   -->   (X & ~Y)

  if (match(Op1, m_c_And(m_Specific(Op0), m_Value(Y))) &&

      (Op1->hasOneUse() || isa<Constant>(Y)))

    return BinaryOperator::CreateAnd(

        Op0, Builder.CreateNot(Y, Y->getName() + ".not"));



  if (Op1->hasOneUse()) {

    Value *Y = nullptr, *Z = nullptr;

    Constant *C = nullptr;
@@ -1926,11 +1932,6 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) { 
      return BinaryOperator::CreateAdd(Op0,

                                      Builder.CreateSub(Z, Y, Op1->getName()));



    // (X - (X & Y))   -->   (X & ~Y)

    if (match(Op1, m_c_And(m_Value(Y), m_Specific(Op0))))

      return BinaryOperator::CreateAnd(Op0,

                                  Builder.CreateNot(Y, Y->getName() + ".not"));



    // Subtracting -1/0 is the same as adding 1/0:

    // sub [nsw] Op0, sext(bool Y) -> add [nsw] Op0, zext(bool Y)

    // 'nuw' is dropped in favor of the canonical form.

llvm/test/Transforms/InstCombine/sub.ll

+1 −1
Original line number Diff line number Diff line
@@ -1531,7 +1531,7 @@ define i8 @test75(i8 %x) { 
; CHECK-LABEL: @test75(

; CHECK-NEXT:    [[T0:%.*]] = and i8 [[X:%.*]], -8

; CHECK-NEXT:    call void @use8(i8 [[T0]])

; CHECK-NEXT:    [[T1:%.*]] = sub i8 [[X]], [[T0]]

; CHECK-NEXT:    [[T1:%.*]] = and i8 [[X]], 7

; CHECK-NEXT:    ret i8 [[T1]]

;

  %t0 = and i8 %x, -8

llvm/test/Transforms/LoopUnroll/runtime-loop-multiple-exits.ll

+2 −2
Original line number Diff line number Diff line
@@ -19,7 +19,7 @@ define void @test1(i64 %trip, i1 %cond) { 
; EPILOG-NEXT:    [[TMP1:%.*]] = icmp ult i64 [[TMP0]], 7

; EPILOG-NEXT:    br i1 [[TMP1]], label %exit2.loopexit.unr-lcssa, label [[ENTRY_NEW:%.*]]

; EPILOG:       entry.new:

; EPILOG-NEXT:    [[UNROLL_ITER:%.*]] = sub i64 [[TRIP]], [[XTRAITER]]

; EPILOG-NEXT:    [[UNROLL_ITER:%.*]] = and i64 [[TRIP]], -8

; EPILOG-NEXT:    br label [[LOOP_HEADER:%.*]]

; EPILOG:  loop_latch.epil:

; EPILOG-NEXT:     %epil.iter.sub = add i64 %epil.iter, -1
@@ -147,7 +147,7 @@ define void @test3(i64 %trip, i64 %add) { 
; EPILOG-NEXT:    [[TMP1:%.*]] = icmp ult i64 [[TMP0]], 7

; EPILOG-NEXT:    br i1 [[TMP1]], label %exit2.loopexit.unr-lcssa, label [[ENTRY_NEW:%.*]]

; EPILOG:       entry.new:

; EPILOG-NEXT:    %unroll_iter = sub i64 [[TRIP]], [[XTRAITER]]

; EPILOG-NEXT:    %unroll_iter = and i64 [[TRIP]], -8

; EPILOG-NEXT:    br label [[LOOP_HEADER:%.*]]

; EPILOG:  loop_header:

; EPILOG-NEXT:     %sum = phi i64 [ 0, %entry.new ], [ %sum.next.7, %loop_latch.7 ]

llvm/test/Transforms/LoopUnroll/runtime-unroll-remainder.ll

+1 −1
Original line number Diff line number Diff line
@@ -21,7 +21,7 @@ for.cond.cleanup: 
; CHECK: br i1 [[CMP]], label %[[CLEANUP:.*]], label %for.body.lr.ph.new



; CHECK-LABEL: for.body.lr.ph.new:

; CHECK: %unroll_iter = sub nsw i64 %wide.trip.count, %xtraiter

; CHECK: %unroll_iter = and i64 %wide.trip.count, 4294967292

; CHECK: br label %for.body



; CHECK: [[CLEANUP]]:

llvm/test/Transforms/LoopVectorize/X86/float-induction-x86.ll

+4 −4
Original line number Diff line number Diff line
@@ -35,7 +35,7 @@ define void @fp_iv_loop1(float* noalias nocapture %A, i32 %N) #0 { 
; AUTO_VEC-NEXT:    [[TMP4:%.*]] = icmp ult i64 [[TMP1]], 96

; AUTO_VEC-NEXT:    br i1 [[TMP4]], label [[MIDDLE_BLOCK_UNR_LCSSA:%.*]], label [[VECTOR_PH_NEW:%.*]]

; AUTO_VEC:       vector.ph.new:

; AUTO_VEC-NEXT:    [[UNROLL_ITER:%.*]] = sub nsw i64 [[TMP3]], [[XTRAITER]]

; AUTO_VEC-NEXT:    [[UNROLL_ITER:%.*]] = and i64 [[TMP3]], 1152921504606846972

; AUTO_VEC-NEXT:    br label [[VECTOR_BODY:%.*]]

; AUTO_VEC:       vector.body:

; AUTO_VEC-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH_NEW]] ], [ [[INDEX_NEXT_3:%.*]], [[VECTOR_BODY]] ]
@@ -203,7 +203,7 @@ define void @fp_iv_loop2(float* noalias nocapture %A, i32 %N) #1 { 
; AUTO_VEC-NEXT:    [[TMP1:%.*]] = icmp ult i64 [[TMP0]], 7

; AUTO_VEC-NEXT:    br i1 [[TMP1]], label [[FOR_END_LOOPEXIT_UNR_LCSSA:%.*]], label [[FOR_BODY_PREHEADER_NEW:%.*]]

; AUTO_VEC:       for.body.preheader.new:

; AUTO_VEC-NEXT:    [[UNROLL_ITER:%.*]] = sub nsw i64 [[ZEXT]], [[XTRAITER]]

; AUTO_VEC-NEXT:    [[UNROLL_ITER:%.*]] = and i64 [[ZEXT]], 4294967288

; AUTO_VEC-NEXT:    br label [[FOR_BODY:%.*]]

; AUTO_VEC:       for.body:

; AUTO_VEC-NEXT:    [[INDVARS_IV:%.*]] = phi i64 [ 0, [[FOR_BODY_PREHEADER_NEW]] ], [ [[INDVARS_IV_NEXT_7:%.*]], [[FOR_BODY]] ]
@@ -306,7 +306,7 @@ define double @external_use_with_fast_math(double* %a, i64 %n) { 
; AUTO_VEC-NEXT:    [[TMP5:%.*]] = icmp ult i64 [[TMP2]], 48

; AUTO_VEC-NEXT:    br i1 [[TMP5]], label [[MIDDLE_BLOCK_UNR_LCSSA:%.*]], label [[VECTOR_PH_NEW:%.*]]

; AUTO_VEC:       vector.ph.new:

; AUTO_VEC-NEXT:    [[UNROLL_ITER:%.*]] = sub nsw i64 [[TMP4]], [[XTRAITER]]

; AUTO_VEC-NEXT:    [[UNROLL_ITER:%.*]] = and i64 [[TMP4]], 2305843009213693948

; AUTO_VEC-NEXT:    br label [[VECTOR_BODY:%.*]]

; AUTO_VEC:       vector.body:

; AUTO_VEC-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH_NEW]] ], [ [[INDEX_NEXT_3:%.*]], [[VECTOR_BODY]] ]
@@ -459,7 +459,7 @@ define double @external_use_without_fast_math(double* %a, i64 %n) { 
; AUTO_VEC-NEXT:    [[TMP2:%.*]] = icmp ult i64 [[TMP1]], 7

; AUTO_VEC-NEXT:    br i1 [[TMP2]], label [[FOR_END_UNR_LCSSA:%.*]], label [[ENTRY_NEW:%.*]]

; AUTO_VEC:       entry.new:

; AUTO_VEC-NEXT:    [[UNROLL_ITER:%.*]] = sub nsw i64 [[SMAX]], [[XTRAITER]]

; AUTO_VEC-NEXT:    [[UNROLL_ITER:%.*]] = and i64 [[SMAX]], 9223372036854775800

; AUTO_VEC-NEXT:    br label [[FOR_BODY:%.*]]

; AUTO_VEC:       for.body:

; AUTO_VEC-NEXT:    [[I:%.*]] = phi i64 [ 0, [[ENTRY_NEW]] ], [ [[I_NEXT_7:%.*]], [[FOR_BODY]] ]