[llvm] r337098 - [InstCombine] Fold x & (-1 >> y) u< x to x u> (-1 >> y)
Roman Lebedev via llvm-commits
llvm-commits at lists.llvm.org
Sat Jul 14 05:20:16 PDT 2018
Author: lebedevri
Date: Sat Jul 14 05:20:16 2018
New Revision: 337098
URL: http://llvm.org/viewvc/llvm-project?rev=337098&view=rev
Log:
[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.
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
llvm/trunk/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ult-to-icmp-ugt.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp?rev=337098&r1=337097&r2=337098&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp Sat Jul 14 05:20:16 2018
@@ -2897,6 +2897,11 @@ static Value *foldICmpWithLowBitMaskedVa
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;
Modified: llvm/trunk/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ult-to-icmp-ugt.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ult-to-icmp-ugt.ll?rev=337098&r1=337097&r2=337098&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ult-to-icmp-ugt.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ult-to-icmp-ugt.ll Sat Jul 14 05:20:16 2018
@@ -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> %
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
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)
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