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InstCombine: add more transforms

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C1-X <u C2 -> (X|(C2-1)) == C1
C1-X >u C2 -> (X|C2) == C1
X-C1 <u C2 -> (X & -C2) == C1
X-C1 >u C2 -> (X & ~C2) == C1


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185909 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Majnemer 2013-07-09 07:50:59 +00:00
parent fa55969acb
commit 377a5c1a87
4 changed files with 87 additions and 5 deletions
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42
lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -1512,6 +1512,30 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
return R;
break;
case Instruction::Sub: {
ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(0));
if (!LHSC) break;
const APInt &LHSV = LHSC->getValue();
// C1-X <u C2 -> (X|(C2-1)) == C1
// iff C1 & (C2-1) == C2-1
// C2 is a power of 2
if (ICI.getPredicate() == ICmpInst::ICMP_ULT && LHSI->hasOneUse() &&
RHSV.isPowerOf2() && (LHSV & (RHSV - 1)) == (RHSV - 1))
return new ICmpInst(ICmpInst::ICMP_EQ,
Builder->CreateOr(LHSI->getOperand(1), RHSV - 1),
LHSC);
// C1-X >u C2 -> (X|C2) == C1
// iff C1 & C2 == C2
// C2+1 is a power of 2
if (ICI.getPredicate() == ICmpInst::ICMP_UGT && LHSI->hasOneUse() &&
(RHSV + 1).isPowerOf2() && (LHSV & RHSV) == RHSV)
return new ICmpInst(ICmpInst::ICMP_NE,
Builder->CreateOr(LHSI->getOperand(1), RHSV), LHSC);
break;
}
case Instruction::Add:
// Fold: icmp pred (add X, C1), C2
if (!ICI.isEquality()) {
@ -1708,6 +1732,24 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
default:
break;
}
// X-C1 <u C2 -> (X & -C2) == C1
// iff C1 & (C2-1) == 0
// C2 is a power of 2
if (ICI.getPredicate() == ICmpInst::ICMP_ULT && LHSI->hasOneUse() &&
RHSV.isPowerOf2() && (LHSV & (RHSV - 1)) == 0)
return new ICmpInst(ICmpInst::ICMP_EQ,
Builder->CreateAnd(LHSI->getOperand(0), -RHSV),
ConstantExpr::getNeg(LHSC));
// X-C1 >u C2 -> (X & ~C2) == C1
// iff C1 & C2 == 0
// C2+1 is a power of 2
if (ICI.getPredicate() == ICmpInst::ICMP_UGT && LHSI->hasOneUse() &&
(RHSV + 1).isPowerOf2() && (LHSV & RHSV) == 0)
return new ICmpInst(ICmpInst::ICMP_NE,
Builder->CreateAnd(LHSI->getOperand(0), ~RHSV),
ConstantExpr::getNeg(LHSC));
}
}
return 0;

4
test/Transforms/InstCombine/2007-01-27-AndICmp.ll
View File

@ -1,8 +1,8 @@
; RUN: opt < %s -instcombine -S | grep "ugt.*, 1"
define i1 @test(i32 %tmp1030) {
%tmp1037 = icmp ne i32 %tmp1030, 40 ; <i1> [#uses=1]
%tmp1039 = icmp ne i32 %tmp1030, 41 ; <i1> [#uses=1]
%tmp1037 = icmp ne i32 %tmp1030, 39 ; <i1> [#uses=1]
%tmp1039 = icmp ne i32 %tmp1030, 40 ; <i1> [#uses=1]
%tmp1042 = and i1 %tmp1037, %tmp1039 ; <i1> [#uses=1]
ret i1 %tmp1042
}

6
test/Transforms/InstCombine/and.ll
View File

@ -186,9 +186,9 @@ define i1 @test25(i32 %A) {
}
define i1 @test26(i32 %A) {
%B = icmp ne i32 %A, 50 ; <i1> [#uses=1]
%C = icmp ne i32 %A, 51 ; <i1> [#uses=1]
;; (A-50) > 1
%B = icmp ne i32 %A, 49 ; <i1> [#uses=1]
%C = icmp ne i32 %A, 50 ; <i1> [#uses=1]
;; (A-49) > 1
%D = and i1 %B, %C ; <i1> [#uses=1]
ret i1 %D
}

40
test/Transforms/InstCombine/icmp.ll
View File

@ -1123,3 +1123,43 @@ define i1 @icmp_add_ult_2(i32 %X) {
%cmp = icmp ult i32 %add, 2
ret i1 %cmp
}
; CHECK: @icmp_add_X_-14_ult_2
; CHECK-NEXT: [[AND:%[a-z0-9]+]] = and i32 %X, -2
; CHECK-NEXT: [[CMP:%[a-z0-9]+]] = icmp eq i32 [[AND]], 14
; CHECK-NEXT: ret i1 [[CMP]]
define i1 @icmp_add_X_-14_ult_2(i32 %X) {
%add = add i32 %X, -14
%cmp = icmp ult i32 %add, 2
ret i1 %cmp
}
; CHECK: @icmp_sub_3_X_ult_2
; CHECK-NEXT: [[OR:%[a-z0-9]+]] = or i32 %X, 1
; CHECK-NEXT: [[CMP:%[a-z0-9]+]] = icmp eq i32 [[OR]], 3
; CHECK-NEXT: ret i1 [[CMP]]
define i1 @icmp_sub_3_X_ult_2(i32 %X) {
%add = sub i32 3, %X
%cmp = icmp ult i32 %add, 2
ret i1 %cmp
}
; CHECK: @icmp_add_X_-14_uge_2
; CHECK-NEXT: [[AND:%[a-z0-9]+]] = and i32 %X, -2
; CHECK-NEXT: [[CMP:%[a-z0-9]+]] = icmp ne i32 [[AND]], 14
; CHECK-NEXT: ret i1 [[CMP]]
define i1 @icmp_add_X_-14_uge_2(i32 %X) {
%add = add i32 %X, -14
%cmp = icmp uge i32 %add, 2
ret i1 %cmp
}
; CHECK: @icmp_sub_3_X_uge_2
; CHECK-NEXT: [[OR:%[a-z0-9]+]] = or i32 %X, 1
; CHECK-NEXT: [[CMP:%[a-z0-9]+]] = icmp ne i32 [[OR]], 3
; CHECK-NEXT: ret i1 [[CMP]]
define i1 @icmp_sub_3_X_uge_2(i32 %X) {
%add = sub i32 3, %X
%cmp = icmp uge i32 %add, 2
ret i1 %cmp
}