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[InstCombine] add folds for icmp (smax X, Y), X

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This is a follow-up to:
https://reviews.llvm.org/rL289855 (D27531)

llvm-svn: 290111
This commit is contained in:
Sanjay Patel 2016-12-19 16:28:53 +00:00
parent ebdc348e5b
commit 534830670e
3 changed files with 56 additions and 55 deletions
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11
include/llvm/IR/PatternMatch.h
View File

@ -1349,15 +1349,22 @@ m_c_Xor(const LHS &L, const RHS &R) {
return m_CombineOr(m_Xor(L, R), m_Xor(R, L));
}
// TODO: Add the related SMax, UMax, UMin commuted matchers.
// TODO: Add the related UMax and UMin commuted matchers.
/// Matches an SMin with LHS and RHS in either order.
template<typename LHS, typename RHS>
template <typename LHS, typename RHS>
inline match_combine_or<MaxMin_match<ICmpInst, LHS, RHS, smin_pred_ty>,
MaxMin_match<ICmpInst, RHS, LHS, smin_pred_ty>>
m_c_SMin(const LHS &L, const RHS &R) {
return m_CombineOr(m_SMin(L, R), m_SMin(R, L));
}
/// Matches an SMax with LHS and RHS in either order.
template <typename LHS, typename RHS>
inline match_combine_or<MaxMin_match<ICmpInst, LHS, RHS, smax_pred_ty>,
MaxMin_match<ICmpInst, RHS, LHS, smax_pred_ty>>
m_c_SMax(const LHS &L, const RHS &R) {
return m_CombineOr(m_SMax(L, R), m_SMax(R, L));
}
} // end namespace PatternMatch
} // end namespace llvm

52
lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -3030,37 +3030,55 @@ Instruction *InstCombiner::foldICmpBinOp(ICmpInst &I) {
return nullptr;
}
/// Fold icmp Pred smin(X, Y), X.
static Instruction *foldICmpWithSMin(ICmpInst &Cmp) {
/// Fold icmp Pred smin|smax(X, Y), X.
static Instruction *foldICmpWithSMinMax(ICmpInst &Cmp) {
ICmpInst::Predicate Pred = Cmp.getPredicate();
Value *Op0 = Cmp.getOperand(0);
Value *X = Cmp.getOperand(1);
// TODO: This should be expanded to handle smax/umax/umin.
// TODO: This should be expanded to handle umax/umin.
// Canonicalize minimum operand to LHS of the icmp.
if (match(X, m_c_SMin(m_Specific(Op0), m_Value()))) {
if (match(X, m_c_SMin(m_Specific(Op0), m_Value())) ||
match(X, m_c_SMax(m_Specific(Op0), m_Value()))) {
std::swap(Op0, X);
Pred = Cmp.getSwappedPredicate();
}
Value *Y;
if (!match(Op0, m_c_SMin(m_Specific(X), m_Value(Y))))
if (match(Op0, m_c_SMin(m_Specific(X), m_Value(Y)))) {
// smin(X, Y) == X --> X <= Y
// smin(X, Y) >= X --> X <= Y
if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_SGE)
return new ICmpInst(ICmpInst::ICMP_SLE, X, Y);
// smin(X, Y) != X --> X > Y
// smin(X, Y) < X --> X > Y
if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::ICMP_SLT)
return new ICmpInst(ICmpInst::ICMP_SGT, X, Y);
// These cases should be handled in InstSimplify:
// smin(X, Y) <= X --> true
// smin(X, Y) > X --> false
return nullptr;
}
if (match(Op0, m_c_SMax(m_Specific(X), m_Value(Y)))) {
// smax(X, Y) == X --> X >= Y
// smax(X, Y) <= X --> X >= Y
if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_SLE)
return new ICmpInst(ICmpInst::ICMP_SGE, X, Y);
// smin(X, Y) == X --> X <= Y
// smin(X, Y) >= X --> X <= Y
if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_SGE)
return new ICmpInst(ICmpInst::ICMP_SLE, X, Y);
// smax(X, Y) != X --> X < Y
// smax(X, Y) > X --> X < Y
if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::ICMP_SGT)
return new ICmpInst(ICmpInst::ICMP_SLT, X, Y);
// smin(X, Y) != X --> X > Y
// smin(X, Y) < X --> X > Y
if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::ICMP_SLT)
return new ICmpInst(ICmpInst::ICMP_SGT, X, Y);
// These cases should be handled in InstSimplify:
// smax(X, Y) >= X --> true
// smax(X, Y) < X --> false
return nullptr;
}
// These cases should be handled in InstSimplify:
// smin(X, Y) <= X --> true
// smin(X, Y) > X --> false
return nullptr;
}
@ -4311,7 +4329,7 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
if (Instruction *Res = foldICmpBinOp(I))
return Res;
if (Instruction *Res = foldICmpWithSMin(I))
if (Instruction *Res = foldICmpWithSMinMax(I))
return Res;
{

48
test/Transforms/InstCombine/smax-icmp.ll
View File

@ -12,9 +12,7 @@
define i1 @eq_smax1(i32 %x, i32 %y) {
; CHECK-LABEL: @eq_smax1(
; CHECK-NEXT: [[CMP1:%.*]] = icmp sgt i32 %x, %y
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP1]], i32 %x, i32 %y
; CHECK-NEXT: [[CMP2:%.*]] = icmp eq i32 [[SEL]], %x
; CHECK-NEXT: [[CMP2:%.*]] = icmp sge i32 %x, %y
; CHECK-NEXT: ret i1 [[CMP2]]
;
%cmp1 = icmp sgt i32 %x, %y
@ -27,9 +25,7 @@ define i1 @eq_smax1(i32 %x, i32 %y) {
define i1 @eq_smax2(i32 %x, i32 %y) {
; CHECK-LABEL: @eq_smax2(
; CHECK-NEXT: [[CMP1:%.*]] = icmp sgt i32 %y, %x
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP1]], i32 %y, i32 %x
; CHECK-NEXT: [[CMP2:%.*]] = icmp eq i32 [[SEL]], %x
; CHECK-NEXT: [[CMP2:%.*]] = icmp sge i32 %x, %y
; CHECK-NEXT: ret i1 [[CMP2]]
;
%cmp1 = icmp sgt i32 %y, %x
@ -43,9 +39,7 @@ define i1 @eq_smax2(i32 %x, i32 %y) {
define i1 @eq_smax3(i32 %a, i32 %y) {
; CHECK-LABEL: @eq_smax3(
; CHECK-NEXT: [[X:%.*]] = add i32 %a, 3
; CHECK-NEXT: [[CMP1:%.*]] = icmp sgt i32 [[X]], %y
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP1]], i32 [[X]], i32 %y
; CHECK-NEXT: [[CMP2:%.*]] = icmp eq i32 [[X]], [[SEL]]
; CHECK-NEXT: [[CMP2:%.*]] = icmp sge i32 [[X]], %y
; CHECK-NEXT: ret i1 [[CMP2]]
;
%x = add i32 %a, 3 ; thwart complexity-based canonicalization
@ -60,9 +54,7 @@ define i1 @eq_smax3(i32 %a, i32 %y) {
define i1 @eq_smax4(i32 %a, i32 %y) {
; CHECK-LABEL: @eq_smax4(
; CHECK-NEXT: [[X:%.*]] = add i32 %a, 3
; CHECK-NEXT: [[CMP1:%.*]] = icmp slt i32 [[X]], %y
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP1]], i32 %y, i32 [[X]]
; CHECK-NEXT: [[CMP2:%.*]] = icmp eq i32 [[X]], [[SEL]]
; CHECK-NEXT: [[CMP2:%.*]] = icmp sge i32 [[X]], %y
; CHECK-NEXT: ret i1 [[CMP2]]
;
%x = add i32 %a, 3 ; thwart complexity-based canonicalization
@ -76,9 +68,7 @@ define i1 @eq_smax4(i32 %a, i32 %y) {
define i1 @sle_smax1(i32 %x, i32 %y) {
; CHECK-LABEL: @sle_smax1(
; CHECK-NEXT: [[CMP1:%.*]] = icmp sgt i32 %x, %y
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP1]], i32 %x, i32 %y
; CHECK-NEXT: [[CMP2:%.*]] = icmp sle i32 [[SEL]], %x
; CHECK-NEXT: [[CMP2:%.*]] = icmp sge i32 %x, %y
; CHECK-NEXT: ret i1 [[CMP2]]
;
%cmp1 = icmp sgt i32 %x, %y
@ -91,9 +81,7 @@ define i1 @sle_smax1(i32 %x, i32 %y) {
define i1 @sle_smax2(i32 %x, i32 %y) {
; CHECK-LABEL: @sle_smax2(
; CHECK-NEXT: [[CMP1:%.*]] = icmp sgt i32 %y, %x
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP1]], i32 %y, i32 %x
; CHECK-NEXT: [[CMP2:%.*]] = icmp sle i32 [[SEL]], %x
; CHECK-NEXT: [[CMP2:%.*]] = icmp sge i32 %x, %y
; CHECK-NEXT: ret i1 [[CMP2]]
;
%cmp1 = icmp sgt i32 %y, %x
@ -107,9 +95,7 @@ define i1 @sle_smax2(i32 %x, i32 %y) {
define i1 @sle_smax3(i32 %a, i32 %y) {
; CHECK-LABEL: @sle_smax3(
; CHECK-NEXT: [[X:%.*]] = add i32 %a, 3
; CHECK-NEXT: [[CMP1:%.*]] = icmp sgt i32 [[X]], %y
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP1]], i32 [[X]], i32 %y
; CHECK-NEXT: [[CMP2:%.*]] = icmp sge i32 [[X]], [[SEL]]
; CHECK-NEXT: [[CMP2:%.*]] = icmp sge i32 [[X]], %y
; CHECK-NEXT: ret i1 [[CMP2]]
;
%x = add i32 %a, 3 ; thwart complexity-based canonicalization
@ -124,9 +110,7 @@ define i1 @sle_smax3(i32 %a, i32 %y) {
define i1 @sle_smax4(i32 %a, i32 %y) {
; CHECK-LABEL: @sle_smax4(
; CHECK-NEXT: [[X:%.*]] = add i32 %a, 3
; CHECK-NEXT: [[CMP1:%.*]] = icmp slt i32 [[X]], %y
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP1]], i32 %y, i32 [[X]]
; CHECK-NEXT: [[CMP2:%.*]] = icmp sge i32 [[X]], [[SEL]]
; CHECK-NEXT: [[CMP2:%.*]] = icmp sge i32 [[X]], %y
; CHECK-NEXT: ret i1 [[CMP2]]
;
%x = add i32 %a, 3 ; thwart complexity-based canonicalization
@ -140,9 +124,7 @@ define i1 @sle_smax4(i32 %a, i32 %y) {
define i1 @ne_smax1(i32 %x, i32 %y) {
; CHECK-LABEL: @ne_smax1(
; CHECK-NEXT: [[CMP1:%.*]] = icmp sgt i32 %x, %y
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP1]], i32 %x, i32 %y
; CHECK-NEXT: [[CMP2:%.*]] = icmp ne i32 [[SEL]], %x
; CHECK-NEXT: [[CMP2:%.*]] = icmp slt i32 %x, %y
; CHECK-NEXT: ret i1 [[CMP2]]
;
%cmp1 = icmp sgt i32 %x, %y
@ -169,9 +151,7 @@ define i1 @ne_smax2(i32 %x, i32 %y) {
define i1 @ne_smax3(i32 %a, i32 %y) {
; CHECK-LABEL: @ne_smax3(
; CHECK-NEXT: [[X:%.*]] = add i32 %a, 3
; CHECK-NEXT: [[CMP1:%.*]] = icmp sgt i32 [[X]], %y
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP1]], i32 [[X]], i32 %y
; CHECK-NEXT: [[CMP2:%.*]] = icmp ne i32 [[X]], [[SEL]]
; CHECK-NEXT: [[CMP2:%.*]] = icmp slt i32 [[X]], %y
; CHECK-NEXT: ret i1 [[CMP2]]
;
%x = add i32 %a, 3 ; thwart complexity-based canonicalization
@ -200,9 +180,7 @@ define i1 @ne_smax4(i32 %a, i32 %y) {
define i1 @sgt_smax1(i32 %x, i32 %y) {
; CHECK-LABEL: @sgt_smax1(
; CHECK-NEXT: [[CMP1:%.*]] = icmp sgt i32 %x, %y
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP1]], i32 %x, i32 %y
; CHECK-NEXT: [[CMP2:%.*]] = icmp sgt i32 [[SEL]], %x
; CHECK-NEXT: [[CMP2:%.*]] = icmp slt i32 %x, %y
; CHECK-NEXT: ret i1 [[CMP2]]
;
%cmp1 = icmp sgt i32 %x, %y
@ -229,9 +207,7 @@ define i1 @sgt_smax2(i32 %x, i32 %y) {
define i1 @sgt_smax3(i32 %a, i32 %y) {
; CHECK-LABEL: @sgt_smax3(
; CHECK-NEXT: [[X:%.*]] = add i32 %a, 3
; CHECK-NEXT: [[CMP1:%.*]] = icmp sgt i32 [[X]], %y
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP1]], i32 [[X]], i32 %y
; CHECK-NEXT: [[CMP2:%.*]] = icmp slt i32 [[X]], [[SEL]]
; CHECK-NEXT: [[CMP2:%.*]] = icmp slt i32 [[X]], %y
; CHECK-NEXT: ret i1 [[CMP2]]
;
%x = add i32 %a, 3 ; thwart complexity-based canonicalization