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[InstCombine] Fold x & (-1 >> y) u< x to x u> (-1 >> y) 

https://bugs.llvm.org/show_bug.cgi?id=38123
https://rise4fun.com/Alive/ocb

This pattern is not commutative. But InstSimplify will
already have taken care of the 'commutative' variant.

llvm-svn: 337098
This commit is contained in:
Roman Lebedev 2018-07-14 12:20:16 +00:00
parent cad4e3d741
commit e3dc587ae0
2 changed files with 19 additions and 20 deletions
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5
llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -2897,6 +2897,11 @@ static Value *foldICmpWithLowBitMaskedVal(ICmpInst &I,
assert(X == I.getOperand(1) && "instsimplify took care of commut. variant");
DstPred = ICmpInst::Predicate::ICMP_ULE;
break;
case ICmpInst::Predicate::ICMP_ULT:
// x & (-1 >> y) u< x -> x u> (-1 >> y)
assert(X == I.getOperand(1) && "instsimplify took care of commut. variant");
DstPred = ICmpInst::Predicate::ICMP_UGT;
break;
// TODO: more folds are possible, https://bugs.llvm.org/show_bug.cgi?id=38123
default:
return nullptr;

34
llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ult-to-icmp-ugt.ll
View File

@ -15,9 +15,8 @@
define i1 @p0(i8 %x) {
; CHECK-LABEL: @p0(
; CHECK-NEXT: [[TMP0:%.*]] = and i8 [[X:%.*]], 3
; CHECK-NEXT: [[RET:%.*]] = icmp ult i8 [[TMP0]], [[X]]
; CHECK-NEXT: ret i1 [[RET]]
; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt i8 [[X:%.*]], 3
; CHECK-NEXT: ret i1 [[TMP1]]
;
%tmp0 = and i8 %x, 3
%ret = icmp ult i8 %tmp0, %x
@ -27,9 +26,8 @@ define i1 @p0(i8 %x) {
define i1 @pv(i8 %x, i8 %y) {
; CHECK-LABEL: @pv(
; CHECK-NEXT: [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[TMP0]], [[X:%.*]]
; CHECK-NEXT: [[RET:%.*]] = icmp ult i8 [[TMP1]], [[X]]
; CHECK-NEXT: ret i1 [[RET]]
; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i8 [[TMP0]], [[X:%.*]]
; CHECK-NEXT: ret i1 [[TMP1]]
;
%tmp0 = lshr i8 -1, %y
%tmp1 = and i8 %tmp0, %x
@ -43,9 +41,8 @@ define i1 @pv(i8 %x, i8 %y) {
define <2 x i1> @p1_vec_splat(<2 x i8> %x) {
; CHECK-LABEL: @p1_vec_splat(
; CHECK-NEXT: [[TMP0:%.*]] = and <2 x i8> [[X:%.*]], <i8 3, i8 3>
; CHECK-NEXT: [[RET:%.*]] = icmp ult <2 x i8> [[TMP0]], [[X]]
; CHECK-NEXT: ret <2 x i1> [[RET]]
; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt <2 x i8> [[X:%.*]], <i8 3, i8 3>
; CHECK-NEXT: ret <2 x i1> [[TMP1]]
;
%tmp0 = and <2 x i8> %x, <i8 3, i8 3>
%ret = icmp ult <2 x i8> %tmp0, %x
@ -54,9 +51,8 @@ define <2 x i1> @p1_vec_splat(<2 x i8> %x) {
define <2 x i1> @p2_vec_nonsplat(<2 x i8> %x) {
; CHECK-LABEL: @p2_vec_nonsplat(
; CHECK-NEXT: [[TMP0:%.*]] = and <2 x i8> [[X:%.*]], <i8 3, i8 15>
; CHECK-NEXT: [[RET:%.*]] = icmp ult <2 x i8> [[TMP0]], [[X]]
; CHECK-NEXT: ret <2 x i1> [[RET]]
; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt <2 x i8> [[X:%.*]], <i8 3, i8 15>
; CHECK-NEXT: ret <2 x i1> [[TMP1]]
;
%tmp0 = and <2 x i8> %x, <i8 3, i8 15> ; doesn't have to be splat.
%ret = icmp ult <2 x i8> %tmp0, %x
@ -65,9 +61,8 @@ define <2 x i1> @p2_vec_nonsplat(<2 x i8> %x) {
define <3 x i1> @p3_vec_splat_undef(<3 x i8> %x) {
; CHECK-LABEL: @p3_vec_splat_undef(
; CHECK-NEXT: [[TMP0:%.*]] = and <3 x i8> [[X:%.*]], <i8 3, i8 undef, i8 3>
; CHECK-NEXT: [[RET:%.*]] = icmp ult <3 x i8> [[TMP0]], [[X]]
; CHECK-NEXT: ret <3 x i1> [[RET]]
; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt <3 x i8> [[X:%.*]], <i8 3, i8 undef, i8 3>
; CHECK-NEXT: ret <3 x i1> [[TMP1]]
;
%tmp0 = and <3 x i8> %x, <i8 3, i8 undef, i8 3>
%ret = icmp ult <3 x i8> %tmp0, %x
@ -100,9 +95,8 @@ define i1 @cv0(i8 %y) {
; CHECK-LABEL: @cv0(
; CHECK-NEXT: [[X:%.*]] = call i8 @gen8()
; CHECK-NEXT: [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[X]], [[TMP0]]
; CHECK-NEXT: [[RET:%.*]] = icmp ult i8 [[TMP1]], [[X]]
; CHECK-NEXT: ret i1 [[RET]]
; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt i8 [[X]], [[TMP0]]
; CHECK-NEXT: ret i1 [[TMP1]]
;
%x = call i8 @gen8()
%tmp0 = lshr i8 -1, %y
@ -145,8 +139,8 @@ define i1 @oneuse0(i8 %x) {
; CHECK-LABEL: @oneuse0(
; CHECK-NEXT: [[TMP0:%.*]] = and i8 [[X:%.*]], 3
; CHECK-NEXT: call void @use8(i8 [[TMP0]])
; CHECK-NEXT: [[RET:%.*]] = icmp ult i8 [[TMP0]], [[X]]
; CHECK-NEXT: ret i1 [[RET]]
; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt i8 [[X]], 3
; CHECK-NEXT: ret i1 [[TMP1]]
;
%tmp0 = and i8 %x, 3
call void @use8(i8 %tmp0)