caio/clang-p2996
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

[InstCombine] allow more matches for logical-ands --> select

Browse Source 
This allows patterns with real 'and' instructions because
those are safe to transform:
https://alive2.llvm.org/ce/z/7-U_Ak
This commit is contained in:
Sanjay Patel
2022-10-22 07:55:19 -04:00
parent f010b1eae5
commit e1bd759ea5
2 changed files with 16 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
View File

@@ -2852,18 +2852,21 @@ Instruction *InstCombinerImpl::visitSelectInst(SelectInst &SI) {
// (C && A) || (!C && B) --> sel C, A, B
// (A && C) || (!C && B) --> sel C, A, B
if (match(FalseVal, m_LogicalAnd(m_Not(m_Value(C)), m_Value(B))) &&
match(CondVal, m_c_LogicalAnd(m_Specific(C), m_Value(A))))
return SelectInst::Create(C, A, B);
// (C && A) || (B && !C) --> sel C, A, B
// TODO: (A && C) || (B && !C) is safe to transform with real 'and' ops.
if (match(FalseVal, m_LogicalAnd(m_Value(B), m_Not(m_Value(C)))) &&
match(CondVal, m_LogicalAnd(m_Specific(C), m_Value(A))))
return SelectInst::Create(C, A, B);
// (A && C) || (B && !C) --> sel C, A, B (only with real 'and' ops)
if (match(FalseVal, m_c_LogicalAnd(m_Not(m_Value(C)), m_Value(B))) &&
match(CondVal, m_c_LogicalAnd(m_Specific(C), m_Value(A)))) {
auto *SelCond = dyn_cast<SelectInst>(CondVal);
auto *SelFVal = dyn_cast<SelectInst>(FalseVal);
if (!SelCond || !SelFVal ||
!match(SelFVal->getTrueValue(),
m_Not(m_Specific(SelCond->getTrueValue()))))
return SelectInst::Create(C, A, B);
}
// (!C && A) || (C && B) --> sel C, B, A
// (!C && A) || (B && C) --> sel C, B, A
// TODO: Allow more commutes as with the previous fold.
if (match(CondVal, m_LogicalAnd(m_Not(m_Value(C)), m_Value(A))) &&
match(FalseVal, m_c_LogicalAnd(m_Specific(C), m_Value(B))))
return SelectInst::Create(C, B, A);

17
llvm/test/Transforms/InstCombine/select-safe-transforms.ll
View File

@@ -529,6 +529,8 @@ define i1 @bools2_logical_commute2_and1_and2(i1 %a, i1 %c) {
ret i1 %or
}
; This is not safe to transform if 'c' could be poison.
define i1 @bools2_logical_commute3(i1 %a, i1 %b, i1 %c) {
; CHECK-LABEL: @bools2_logical_commute3(
; CHECK-NEXT: [[NOT:%.*]] = xor i1 [[C:%.*]], true
@@ -546,10 +548,7 @@ define i1 @bools2_logical_commute3(i1 %a, i1 %b, i1 %c) {
define i1 @bools2_logical_commute3_and1(i1 %a, i1 %b, i1 %c) {
; CHECK-LABEL: @bools2_logical_commute3_and1(
; CHECK-NEXT: [[NOT:%.*]] = xor i1 [[C:%.*]], true
; CHECK-NEXT: [[AND1:%.*]] = and i1 [[A:%.*]], [[C]]
; CHECK-NEXT: [[AND2:%.*]] = select i1 [[B:%.*]], i1 [[NOT]], i1 false
; CHECK-NEXT: [[OR:%.*]] = select i1 [[AND1]], i1 true, i1 [[AND2]]
; CHECK-NEXT: [[OR:%.*]] = select i1 [[C:%.*]], i1 [[A:%.*]], i1 [[B:%.*]]
; CHECK-NEXT: ret i1 [[OR]]
;
%not = xor i1 %c, -1
@@ -562,10 +561,7 @@ define i1 @bools2_logical_commute3_and1(i1 %a, i1 %b, i1 %c) {
define i1 @bools2_logical_commute3_and2(i1 %a, i1 %c) {
; CHECK-LABEL: @bools2_logical_commute3_and2(
; CHECK-NEXT: [[B:%.*]] = call i1 @gen1()
; CHECK-NEXT: [[NOT:%.*]] = xor i1 [[C:%.*]], true
; CHECK-NEXT: [[AND1:%.*]] = select i1 [[A:%.*]], i1 [[C]], i1 false
; CHECK-NEXT: [[AND2:%.*]] = and i1 [[B]], [[NOT]]
; CHECK-NEXT: [[OR:%.*]] = select i1 [[AND1]], i1 true, i1 [[AND2]]
; CHECK-NEXT: [[OR:%.*]] = select i1 [[C:%.*]], i1 [[A:%.*]], i1 [[B]]
; CHECK-NEXT: ret i1 [[OR]]
;
%b = call i1 @gen1()
@@ -579,10 +575,7 @@ define i1 @bools2_logical_commute3_and2(i1 %a, i1 %c) {
define i1 @bools2_logical_commute3_and1_and2(i1 %a, i1 %c) {
; CHECK-LABEL: @bools2_logical_commute3_and1_and2(
; CHECK-NEXT: [[B:%.*]] = call i1 @gen1()
; CHECK-NEXT: [[NOT:%.*]] = xor i1 [[C:%.*]], true
; CHECK-NEXT: [[AND1:%.*]] = and i1 [[A:%.*]], [[C]]
; CHECK-NEXT: [[AND2:%.*]] = and i1 [[B]], [[NOT]]
; CHECK-NEXT: [[OR:%.*]] = select i1 [[AND1]], i1 true, i1 [[AND2]]
; CHECK-NEXT: [[OR:%.*]] = select i1 [[C:%.*]], i1 [[A:%.*]], i1 [[B]]
; CHECK-NEXT: ret i1 [[OR]]
;
%b = call i1 @gen1()