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[InstCombine] canonicalize zext-and-of-bool compare to narrow and 

https://alive2.llvm.org/ce/z/3jYbEH

We should choose one of these forms, and the option that uses
the narrow type allows the motivating example from issue #56294
to reduce. In the best case (no 'not' needed and 'trunc' remains),
this does remove an instruction.

Note that there is what looks like a regression because there
is an existing canonicalization that turns trunc into and+icmp.
That is a long-standing transform, and I'm not sure what effect
reversing it would have.
This commit is contained in:
Sanjay Patel 2022-07-29 11:28:51 -04:00
parent 26821f75ed
commit b5a9361c90
3 changed files with 34 additions and 14 deletions
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13
llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -1904,6 +1904,19 @@ Instruction *InstCombinerImpl::foldICmpAndConstant(ICmpInst &Cmp,
return new ICmpInst(NewPred, X, SubOne(cast<Constant>(Cmp.getOperand(1))));
}
// ((zext i1 X) & Y) == 0 --> !((trunc Y) & X)
// ((zext i1 X) & Y) != 0 --> ((trunc Y) & X)
if (match(And, m_OneUse(m_c_And(m_OneUse(m_ZExt(m_Value(X))), m_Value(Y)))) &&
C.isZero() && X->getType()->isIntOrIntVectorTy(1)) {
Value *TruncY = Builder.CreateTrunc(Y, X->getType());
if (Pred == CmpInst::ICMP_EQ) {
Value *And = Builder.CreateAnd(TruncY, X);
return BinaryOperator::CreateNot(And);
}
assert(Pred == CmpInst::ICMP_NE && "Unexpected predicate");
return BinaryOperator::CreateAnd(TruncY, X);
}
return nullptr;
}

6
llvm/test/Transforms/InstCombine/and-xor-or.ll
View File

@ -4345,11 +4345,7 @@ define i32 @or_sext_sext_use1(i8 %x, i4 %y) {
define i1 @PR56294(i8 %x) {
; CHECK-LABEL: define {{[^@]+}}@PR56294
; CHECK-SAME: (i8 [[X:%.*]]) {
; CHECK-NEXT: [[T2:%.*]] = icmp eq i8 [[X]], 2
; CHECK-NEXT: [[TMP1:%.*]] = zext i1 [[T2]] to i8
; CHECK-NEXT: [[TMP2:%.*]] = and i8 [[TMP1]], [[X]]
; CHECK-NEXT: [[T7:%.*]] = icmp ne i8 [[TMP2]], 0
; CHECK-NEXT: ret i1 [[T7]]
; CHECK-NEXT: ret i1 false
;
%t2 = icmp eq i8 %x, 2
%t3 = and i8 %x, 1

29
llvm/test/Transforms/InstCombine/icmp.ll
View File

@ -4113,9 +4113,10 @@ define i1 @signbit_true_logic_uses_commute(i64 %x) {
define i1 @zext_bool_and_eq0(i1 %x, i8 %y) {
; CHECK-LABEL: @zext_bool_and_eq0(
; CHECK-NEXT: [[ZX:%.*]] = zext i1 [[X:%.*]] to i8
; CHECK-NEXT: [[A:%.*]] = and i8 [[ZX]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[A]], 0
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[Y:%.*]], 1
; CHECK-NEXT: [[TMP2:%.*]] = icmp ne i8 [[TMP1]], 0
; CHECK-NEXT: [[TMP3:%.*]] = and i1 [[TMP2]], [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = xor i1 [[TMP3]], true
; CHECK-NEXT: ret i1 [[R]]
;
%zx = zext i1 %x to i8
@ -4126,9 +4127,9 @@ define i1 @zext_bool_and_eq0(i1 %x, i8 %y) {
define <2 x i1> @zext_bool_and_eq0_commute(<2 x i1> %x, <2 x i8> %p) {
; CHECK-LABEL: @zext_bool_and_eq0_commute(
; CHECK-NEXT: [[ZX:%.*]] = zext <2 x i1> [[X:%.*]] to <2 x i8>
; CHECK-NEXT: [[A:%.*]] = and <2 x i8> [[ZX]], [[P:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp eq <2 x i8> [[A]], zeroinitializer
; CHECK-NEXT: [[TMP1:%.*]] = trunc <2 x i8> [[P:%.*]] to <2 x i1>
; CHECK-NEXT: [[TMP2:%.*]] = and <2 x i1> [[TMP1]], [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = xor <2 x i1> [[TMP2]], <i1 true, i1 true>
; CHECK-NEXT: ret <2 x i1> [[R]]
;
%y = mul <2 x i8> %p, %p ; thwart complexity-based canonicalization
@ -4140,9 +4141,9 @@ define <2 x i1> @zext_bool_and_eq0_commute(<2 x i1> %x, <2 x i8> %p) {
define i1 @zext_bool_and_ne0(i1 %x, i8 %y) {
; CHECK-LABEL: @zext_bool_and_ne0(
; CHECK-NEXT: [[ZX:%.*]] = zext i1 [[X:%.*]] to i8
; CHECK-NEXT: [[A:%.*]] = and i8 [[ZX]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[A]], 0
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[Y:%.*]], 1
; CHECK-NEXT: [[TMP2:%.*]] = icmp ne i8 [[TMP1]], 0
; CHECK-NEXT: [[R:%.*]] = and i1 [[TMP2]], [[X:%.*]]
; CHECK-NEXT: ret i1 [[R]]
;
%zx = zext i1 %x to i8
@ -4151,6 +4152,8 @@ define i1 @zext_bool_and_ne0(i1 %x, i8 %y) {
ret i1 %r
}
; TODO: This should transform similarly to eq/ne 0.
define i1 @zext_bool_and_ne1(i1 %x, i8 %y) {
; CHECK-LABEL: @zext_bool_and_ne1(
; CHECK-NEXT: [[ZX:%.*]] = zext i1 [[X:%.*]] to i8
@ -4164,6 +4167,8 @@ define i1 @zext_bool_and_ne1(i1 %x, i8 %y) {
ret i1 %r
}
; negative test - wrong logic op
define i1 @zext_bool_or_eq0(i1 %x, i8 %y) {
; CHECK-LABEL: @zext_bool_or_eq0(
; CHECK-NEXT: [[ZX:%.*]] = zext i1 [[X:%.*]] to i8
@ -4177,6 +4182,8 @@ define i1 @zext_bool_or_eq0(i1 %x, i8 %y) {
ret i1 %r
}
; negative test - extra use
define i1 @zext_bool_and_eq0_use(i1 %x, i64 %y) {
; CHECK-LABEL: @zext_bool_and_eq0_use(
; CHECK-NEXT: [[ZX:%.*]] = zext i1 [[X:%.*]] to i64
@ -4192,6 +4199,8 @@ define i1 @zext_bool_and_eq0_use(i1 %x, i64 %y) {
ret i1 %r
}
; negative test - extra use
define i1 @zext_bool_and_ne0_use(i1 %x, i64 %y) {
; CHECK-LABEL: @zext_bool_and_ne0_use(
; CHECK-NEXT: [[ZX:%.*]] = zext i1 [[X:%.*]] to i64
@ -4207,6 +4216,8 @@ define i1 @zext_bool_and_ne0_use(i1 %x, i64 %y) {
ret i1 %r
}
; negative test - must zext from i1
define i1 @zext_notbool_and_ne0(i2 %x, i8 %y) {
; CHECK-LABEL: @zext_notbool_and_ne0(
; CHECK-NEXT: [[ZX:%.*]] = zext i2 [[X:%.*]] to i8