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[InstCombine] Fold x u> x & C to x u> C

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

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

llvm-svn: 337100
This commit is contained in:
Roman Lebedev 2018-07-14 16:44:43 +00:00
parent b2d8c29aaf
commit 4237d3a0f8
2 changed files with 19 additions and 20 deletions
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5
lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -2892,6 +2892,11 @@ static Value *foldICmpWithLowBitMaskedVal(ICmpInst &I,
// x & (-1 >> y) != x -> x u> (-1 >> y)
DstPred = ICmpInst::Predicate::ICMP_UGT;
break;
case ICmpInst::Predicate::ICMP_UGT:
// x u> x & (-1 >> y) -> x u> (-1 >> y)
assert(X == I.getOperand(0) && "instsimplify took care of commut. variant");
DstPred = ICmpInst::Predicate::ICMP_UGT;
break;
case ICmpInst::Predicate::ICMP_UGE:
// x & (-1 >> y) u>= x -> x u<= (-1 >> y)
assert(X == I.getOperand(1) && "instsimplify took care of commut. variant");

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

@ -20,9 +20,8 @@ declare <3 x i8> @gen3x8()
define i1 @p0() {
; CHECK-LABEL: @p0(
; CHECK-NEXT: [[X:%.*]] = call i8 @gen8()
; CHECK-NEXT: [[TMP0:%.*]] = and i8 [[X]], 3
; CHECK-NEXT: [[RET:%.*]] = icmp ugt i8 [[X]], [[TMP0]]
; CHECK-NEXT: ret i1 [[RET]]
; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt i8 [[X]], 3
; CHECK-NEXT: ret i1 [[TMP1]]
;
%x = call i8 @gen8()
%tmp0 = and i8 %x, 3
@ -34,9 +33,8 @@ define i1 @pv(i8 %y) {
; CHECK-LABEL: @pv(
; CHECK-NEXT: [[X:%.*]] = call i8 @gen8()
; CHECK-NEXT: [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[TMP0]], [[X]]
; CHECK-NEXT: [[RET:%.*]] = icmp ugt i8 [[X]], [[TMP1]]
; 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
@ -52,9 +50,8 @@ define i1 @pv(i8 %y) {
define <2 x i1> @p1_vec_splat() {
; CHECK-LABEL: @p1_vec_splat(
; CHECK-NEXT: [[X:%.*]] = call <2 x i8> @gen2x8()
; CHECK-NEXT: [[TMP0:%.*]] = and <2 x i8> [[X]], <i8 3, i8 3>
; CHECK-NEXT: [[RET:%.*]] = icmp ugt <2 x i8> [[X]], [[TMP0]]
; 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]]
;
%x = call <2 x i8> @gen2x8()
%tmp0 = and <2 x i8> %x, <i8 3, i8 3>
@ -65,9 +62,8 @@ define <2 x i1> @p1_vec_splat() {
define <2 x i1> @p2_vec_nonsplat() {
; CHECK-LABEL: @p2_vec_nonsplat(
; CHECK-NEXT: [[X:%.*]] = call <2 x i8> @gen2x8()
; CHECK-NEXT: [[TMP0:%.*]] = and <2 x i8> [[X]], <i8 3, i8 15>
; CHECK-NEXT: [[RET:%.*]] = icmp ugt <2 x i8> [[X]], [[TMP0]]
; 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]]
;
%x = call <2 x i8> @gen2x8()
%tmp0 = and <2 x i8> %x, <i8 3, i8 15> ; doesn't have to be splat.
@ -78,9 +74,8 @@ define <2 x i1> @p2_vec_nonsplat() {
define <3 x i1> @p3_vec_splat_undef() {
; CHECK-LABEL: @p3_vec_splat_undef(
; CHECK-NEXT: [[X:%.*]] = call <3 x i8> @gen3x8()
; CHECK-NEXT: [[TMP0:%.*]] = and <3 x i8> [[X]], <i8 3, i8 undef, i8 3>
; CHECK-NEXT: [[RET:%.*]] = icmp ugt <3 x i8> [[X]], [[TMP0]]
; 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]]
;
%x = call <3 x i8> @gen3x8()
%tmp0 = and <3 x i8> %x, <i8 3, i8 undef, i8 3>
@ -109,9 +104,8 @@ 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 [[TMP0]], [[X]]
; CHECK-NEXT: [[RET:%.*]] = icmp ugt i8 [[X]], [[TMP1]]
; 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
@ -153,8 +147,8 @@ define i1 @oneuse0() {
; CHECK-NEXT: [[X:%.*]] = call i8 @gen8()
; CHECK-NEXT: [[TMP0:%.*]] = and i8 [[X]], 3
; CHECK-NEXT: call void @use8(i8 [[TMP0]])
; CHECK-NEXT: [[RET:%.*]] = icmp ugt i8 [[X]], [[TMP0]]
; CHECK-NEXT: ret i1 [[RET]]
; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt i8 [[X]], 3
; CHECK-NEXT: ret i1 [[TMP1]]
;
%x = call i8 @gen8()
%tmp0 = and i8 %x, 3