[llvm] 5a6e66e - [InstCombine] add folds for icmp+ctpop
Philip Reames via llvm-commits
llvm-commits at lists.llvm.org
Mon Oct 26 18:50:47 PDT 2020
Are you going to handle other variants? A few of potentials...
ctpop(X) != 0 ==> X != 0.
ctpop(X) == C ==> X != C2 where all but one bit in X is known
ctpop(X) > C ==> X & (C2) != 0 where C bits of X are known one and C2 is
the inverse known zero mask.
Philip
On 10/26/20 1:49 PM, Sanjay Patel via llvm-commits wrote:
> Author: Sanjay Patel
> Date: 2020-10-26T16:48:56-04:00
> New Revision: 5a6e66ec72382d370046e04c415f8c3cb7e8b68d
>
> URL: https://github.com/llvm/llvm-project/commit/5a6e66ec72382d370046e04c415f8c3cb7e8b68d
> DIFF: https://github.com/llvm/llvm-project/commit/5a6e66ec72382d370046e04c415f8c3cb7e8b68d.diff
>
> LOG: [InstCombine] add folds for icmp+ctpop
>
> 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)
>
> Added:
>
>
> Modified:
> llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
> llvm/test/Transforms/InstCombine/cmp-intrinsic.ll
>
> Removed:
>
>
>
> ################################################################################
> diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
> index 24713d7681b2..fe342dc2fc6c 100644
> --- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
> +++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
> @@ -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)) {
>
> diff --git a/llvm/test/Transforms/InstCombine/cmp-intrinsic.ll b/llvm/test/Transforms/InstCombine/cmp-intrinsic.ll
> index 6519eda41499..599a749954d2 100644
> --- a/llvm/test/Transforms/InstCombine/cmp-intrinsic.ll
> +++ b/llvm/test/Transforms/InstCombine/cmp-intrinsic.ll
> @@ -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)
>
>
>
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
More information about the llvm-commits
mailing list