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[InstCombine] add folds for icmp+ctpop

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https://alive2.llvm.org/ce/z/XjFPQJ

  define void @src(i64 %value) {
    %t0 = call i64 @llvm.ctpop.i64(i64 %value)
    %gt = icmp ugt i64 %t0, 63
    %lt = icmp ult i64 %t0, 64
    call void @use(i1 %gt, i1 %lt)
    ret void
  }

  define void @tgt(i64 %value) {
    %eq = icmp eq i64 %value, -1
    %ne = icmp ne i64 %value, -1
    call void @use(i1 %eq, i1 %ne)
    ret void
  }

  declare i64 @llvm.ctpop.i64(i64) #1
  declare void @use(i1, i1)
This commit is contained in:
Sanjay Patel 2020-10-26 16:28:01 -04:00
parent f92ef4754f
commit 52d6694ea4
2 changed files with 14 additions and 3 deletions
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12
lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -3174,6 +3174,18 @@ Instruction *InstCombinerImpl::foldICmpIntrinsicWithConstant(ICmpInst &Cmp,
unsigned BitWidth = C.getBitWidth();
ICmpInst::Predicate Pred = Cmp.getPredicate();
switch (II->getIntrinsicID()) {
case Intrinsic::ctpop: {
// (ctpop X > BitWidth - 1) --> X == -1
Value *X = II->getArgOperand(0);
if (C == BitWidth - 1 && Pred == ICmpInst::ICMP_UGT)
return CmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_EQ, X,
ConstantInt::getAllOnesValue(Ty));
// (ctpop X < BitWidth) --> X != -1
if (C == BitWidth && Pred == ICmpInst::ICMP_ULT)
return CmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_NE, X,
ConstantInt::getAllOnesValue(Ty));
break;
}
case Intrinsic::ctlz: {
// ctlz(0bXXXXXXXX) > 3 -> 0bXXXXXXXX < 0b00010000
if (Pred == ICmpInst::ICMP_UGT && C.ult(BitWidth)) {

5
test/Transforms/InstCombine/cmp-intrinsic.ll
View File

@ -495,7 +495,7 @@ define i1 @ctpop_ugt_bitwidth_minus_one_i8(i8 %x, i8* %p) {
; CHECK-LABEL: @ctpop_ugt_bitwidth_minus_one_i8(
; CHECK-NEXT: [[POP:%.*]] = tail call i8 @llvm.ctpop.i8(i8 [[X:%.*]]), [[RNG2:!range !.*]]
; CHECK-NEXT: store i8 [[POP]], i8* [[P:%.*]], align 1
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i8 [[POP]], 7
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[X]], -1
; CHECK-NEXT: ret i1 [[CMP]]
;
%pop = tail call i8 @llvm.ctpop.i8(i8 %x)
@ -506,8 +506,7 @@ define i1 @ctpop_ugt_bitwidth_minus_one_i8(i8 %x, i8* %p) {
define <2 x i1> @ctpop_ult_bitwidth_v2i32(<2 x i32> %x) {
; CHECK-LABEL: @ctpop_ult_bitwidth_v2i32(
; CHECK-NEXT: [[POP:%.*]] = tail call <2 x i32> @llvm.ctpop.v2i32(<2 x i32> [[X:%.*]])
; CHECK-NEXT: [[CMP:%.*]] = icmp ult <2 x i32> [[POP]], <i32 32, i32 32>
; CHECK-NEXT: [[CMP:%.*]] = icmp ne <2 x i32> [[X:%.*]], <i32 -1, i32 -1>
; CHECK-NEXT: ret <2 x i1> [[CMP]]
;
%pop = tail call <2 x i32> @llvm.ctpop.v2i32(<2 x i32> %x)