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[InstCombine] Fold (x < y) ? -1 : zext(x != y) into u/scmp(x,y) #101049

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merged 13 commits into from
Aug 19, 2024
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[InstCombine] Fold (x < y) ? -1 : zext(x != y) into u/scmp(x,y) #101049

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7513a57
Precommit tests
Poseydon42 Jul 29, 2024
2903765
[InstCombine] Fold (x [us]< y) ? -1 : (x != y) into [us]cmp(x, y)
Poseydon42 Jul 29, 2024
91bb1f2
Update tests
Poseydon42 Jul 29, 2024
2dbc1fd
Add support for vector types
Poseydon42 Jul 29, 2024
9b9bc2e
Update existing tests
Poseydon42 Jul 29, 2024
84dd5e8
Move the fold up
Poseydon42 Jul 29, 2024
00006d1
Full rewrite to accomodate two more folds
Poseydon42 Aug 10, 2024
37d6027
Update tests
Poseydon42 Aug 10, 2024
0fae60f
Update preexisting tests
Poseydon42 Aug 10, 2024
719e474
Address review comments
Poseydon42 Aug 12, 2024
ad2ac72
Update the test with regression
Poseydon42 Aug 14, 2024
e7da912
Format the code
Poseydon42 Aug 14, 2024
12d1a95
Address review comments 2
Poseydon42 Aug 16, 2024
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Precommit tests
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@Poseydon42
Poseydon42 committed Aug 16, 2024
commit 7513a57f5af9c77a0d1fd6f1ca6aa8323833161e
99 changes: 99 additions & 0 deletions llvm/test/Transforms/InstCombine/scmp.ll
View file
Original file line number Diff line number Diff line change
@@ -208,3 +208,102 @@ define i8 @scmp_negated_multiuse(i32 %x, i32 %y) {
%2 = sub i8 0, %1
ret i8 %2
}

; Fold ((x s< y) ? -1 : (x != y)) into scmp(x, y)
define i8 @scmp_from_select(i32 %x, i32 %y) {
; CHECK-LABEL: define i8 @scmp_from_select(
; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
; CHECK-NEXT: [[NE_BOOL:%.*]] = icmp ne i32 [[X]], [[Y]]
; CHECK-NEXT: [[NE:%.*]] = zext i1 [[NE_BOOL]] to i8
; CHECK-NEXT: [[LT:%.*]] = icmp slt i32 [[X]], [[Y]]
; CHECK-NEXT: [[R:%.*]] = select i1 [[LT]], i8 -1, i8 [[NE]]
; CHECK-NEXT: ret i8 [[R]]
;
%ne_bool = icmp ne i32 %x, %y
%ne = zext i1 %ne_bool to i8
%lt = icmp slt i32 %x, %y
%r = select i1 %lt, i8 -1, i8 %ne
ret i8 %r
}

; Negative test: false value of the select is not `icmp ne x, y`
define i8 @scmp_from_select_neg1(i32 %x, i32 %y) {
; CHECK-LABEL: define i8 @scmp_from_select_neg1(
; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
; CHECK-NEXT: [[NE_BOOL:%.*]] = icmp eq i32 [[X]], [[Y]]
; CHECK-NEXT: [[NE:%.*]] = zext i1 [[NE_BOOL]] to i8
; CHECK-NEXT: [[LT:%.*]] = icmp slt i32 [[X]], [[Y]]
; CHECK-NEXT: [[R:%.*]] = select i1 [[LT]], i8 -1, i8 [[NE]]
; CHECK-NEXT: ret i8 [[R]]
;
%ne_bool = icmp eq i32 %x, %y
%ne = zext i1 %ne_bool to i8
%lt = icmp slt i32 %x, %y
%r = select i1 %lt, i8 -1, i8 %ne
ret i8 %r
}

define i8 @scmp_from_select_neg2(i32 %x, i32 %y) {
; CHECK-LABEL: define i8 @scmp_from_select_neg2(
; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
; CHECK-NEXT: [[NE_BOOL:%.*]] = icmp ne i32 [[Y]], [[X]]
; CHECK-NEXT: [[NE:%.*]] = zext i1 [[NE_BOOL]] to i8
; CHECK-NEXT: [[LT:%.*]] = icmp slt i32 [[X]], [[Y]]
; CHECK-NEXT: [[R:%.*]] = select i1 [[LT]], i8 -1, i8 [[NE]]
; CHECK-NEXT: ret i8 [[R]]
;
%ne_bool = icmp ne i32 %y, %x
%ne = zext i1 %ne_bool to i8
%lt = icmp slt i32 %x, %y
%r = select i1 %lt, i8 -1, i8 %ne
ret i8 %r
}

; Negative test: true value of select is not -1
define i8 @scmp_from_select_neg3(i32 %x, i32 %y) {
; CHECK-LABEL: define i8 @scmp_from_select_neg3(
; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
; CHECK-NEXT: [[NE_BOOL:%.*]] = icmp ne i32 [[X]], [[Y]]
; CHECK-NEXT: [[NE:%.*]] = zext i1 [[NE_BOOL]] to i8
; CHECK-NEXT: [[LT:%.*]] = icmp slt i32 [[X]], [[Y]]
; CHECK-NEXT: [[R:%.*]] = select i1 [[LT]], i8 2, i8 [[NE]]
; CHECK-NEXT: ret i8 [[R]]
;
%ne_bool = icmp ne i32 %x, %y
%ne = zext i1 %ne_bool to i8
%lt = icmp slt i32 %x, %y
%r = select i1 %lt, i8 2, i8 %ne
ret i8 %r
}

; Negative test: false value of select is sign-extended instead of zero-extended
define i8 @scmp_from_select_neg4(i32 %x, i32 %y) {
; CHECK-LABEL: define i8 @scmp_from_select_neg4(
; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
; CHECK-NEXT: [[NE_BOOL:%.*]] = icmp ne i32 [[X]], [[Y]]
; CHECK-NEXT: [[R:%.*]] = sext i1 [[NE_BOOL]] to i8
; CHECK-NEXT: ret i8 [[R]]
;
%ne_bool = icmp ne i32 %x, %y
%ne = sext i1 %ne_bool to i8
%lt = icmp slt i32 %x, %y
%r = select i1 %lt, i8 -1, i8 %ne
ret i8 %r
}

; Negative test: condition of select is not (x s< y)
define i8 @scmp_from_select_neg5(i32 %x, i32 %y) {
; CHECK-LABEL: define i8 @scmp_from_select_neg5(
; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
; CHECK-NEXT: [[NE_BOOL:%.*]] = icmp ne i32 [[X]], [[Y]]
; CHECK-NEXT: [[NE:%.*]] = zext i1 [[NE_BOOL]] to i8
; CHECK-NEXT: [[LT:%.*]] = icmp sgt i32 [[X]], [[Y]]
; CHECK-NEXT: [[R:%.*]] = select i1 [[LT]], i8 -1, i8 [[NE]]
; CHECK-NEXT: ret i8 [[R]]
;
%ne_bool = icmp ne i32 %x, %y
%ne = zext i1 %ne_bool to i8
%lt = icmp sgt i32 %x, %y
%r = select i1 %lt, i8 -1, i8 %ne
ret i8 %r
}
99 changes: 99 additions & 0 deletions llvm/test/Transforms/InstCombine/ucmp.ll
View file
Original file line number Diff line number Diff line change
@@ -207,3 +207,102 @@ define i8 @ucmp_negated_multiuse(i32 %x, i32 %y) {
%2 = sub i8 0, %1
ret i8 %2
}

; Fold ((x u< y) ? -1 : (x != y)) into ucmp(x, y)
define i8 @ucmp_from_select(i32 %x, i32 %y) {
; CHECK-LABEL: define i8 @ucmp_from_select(
; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
; CHECK-NEXT: [[NE_BOOL:%.*]] = icmp ne i32 [[X]], [[Y]]
; CHECK-NEXT: [[NE:%.*]] = zext i1 [[NE_BOOL]] to i8
; CHECK-NEXT: [[LT:%.*]] = icmp ult i32 [[X]], [[Y]]
; CHECK-NEXT: [[R:%.*]] = select i1 [[LT]], i8 -1, i8 [[NE]]
; CHECK-NEXT: ret i8 [[R]]
;
%ne_bool = icmp ne i32 %x, %y
%ne = zext i1 %ne_bool to i8
%lt = icmp ult i32 %x, %y
%r = select i1 %lt, i8 -1, i8 %ne
ret i8 %r
}

; Negative test: false value of the select is not `icmp ne x, y`
define i8 @ucmp_from_select_neg1(i32 %x, i32 %y) {
; CHECK-LABEL: define i8 @ucmp_from_select_neg1(
; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
; CHECK-NEXT: [[NE_BOOL:%.*]] = icmp eq i32 [[X]], [[Y]]
; CHECK-NEXT: [[NE:%.*]] = zext i1 [[NE_BOOL]] to i8
; CHECK-NEXT: [[LT:%.*]] = icmp ult i32 [[X]], [[Y]]
; CHECK-NEXT: [[R:%.*]] = select i1 [[LT]], i8 -1, i8 [[NE]]
; CHECK-NEXT: ret i8 [[R]]
;
%ne_bool = icmp eq i32 %x, %y
%ne = zext i1 %ne_bool to i8
%lt = icmp ult i32 %x, %y
%r = select i1 %lt, i8 -1, i8 %ne
ret i8 %r
}

define i8 @ucmp_from_select_neg2(i32 %x, i32 %y) {
; CHECK-LABEL: define i8 @ucmp_from_select_neg2(
; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
; CHECK-NEXT: [[NE_BOOL:%.*]] = icmp ne i32 [[Y]], [[X]]
; CHECK-NEXT: [[NE:%.*]] = zext i1 [[NE_BOOL]] to i8
; CHECK-NEXT: [[LT:%.*]] = icmp ult i32 [[X]], [[Y]]
; CHECK-NEXT: [[R:%.*]] = select i1 [[LT]], i8 -1, i8 [[NE]]
; CHECK-NEXT: ret i8 [[R]]
;
%ne_bool = icmp ne i32 %y, %x
%ne = zext i1 %ne_bool to i8
%lt = icmp ult i32 %x, %y
%r = select i1 %lt, i8 -1, i8 %ne
ret i8 %r
}

; Negative test: true value of select is not -1
define i8 @ucmp_from_select_neg3(i32 %x, i32 %y) {
; CHECK-LABEL: define i8 @ucmp_from_select_neg3(
; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
; CHECK-NEXT: [[NE_BOOL:%.*]] = icmp ne i32 [[X]], [[Y]]
; CHECK-NEXT: [[NE:%.*]] = zext i1 [[NE_BOOL]] to i8
; CHECK-NEXT: [[LT:%.*]] = icmp ult i32 [[X]], [[Y]]
; CHECK-NEXT: [[R:%.*]] = select i1 [[LT]], i8 2, i8 [[NE]]
; CHECK-NEXT: ret i8 [[R]]
;
%ne_bool = icmp ne i32 %x, %y
%ne = zext i1 %ne_bool to i8
%lt = icmp ult i32 %x, %y
%r = select i1 %lt, i8 2, i8 %ne
ret i8 %r
}

; Negative test: false value of select is sign-extended instead of zero-extended
define i8 @ucmp_from_select_neg4(i32 %x, i32 %y) {
; CHECK-LABEL: define i8 @ucmp_from_select_neg4(
; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
; CHECK-NEXT: [[NE_BOOL:%.*]] = icmp ne i32 [[X]], [[Y]]
; CHECK-NEXT: [[R:%.*]] = sext i1 [[NE_BOOL]] to i8
; CHECK-NEXT: ret i8 [[R]]
;
%ne_bool = icmp ne i32 %x, %y
%ne = sext i1 %ne_bool to i8
%lt = icmp ult i32 %x, %y
%r = select i1 %lt, i8 -1, i8 %ne
ret i8 %r
}

; Negative test: condition of select is not (x s< y)
define i8 @ucmp_from_select_neg5(i32 %x, i32 %y) {
; CHECK-LABEL: define i8 @ucmp_from_select_neg5(
; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
; CHECK-NEXT: [[NE_BOOL:%.*]] = icmp ne i32 [[X]], [[Y]]
; CHECK-NEXT: [[NE:%.*]] = zext i1 [[NE_BOOL]] to i8
; CHECK-NEXT: [[LT_NOT:%.*]] = icmp ugt i32 [[X]], [[Y]]
; CHECK-NEXT: [[R:%.*]] = select i1 [[LT_NOT]], i8 [[NE]], i8 -1
; CHECK-NEXT: ret i8 [[R]]
;
%ne_bool = icmp ne i32 %x, %y
%ne = zext i1 %ne_bool to i8
%lt = icmp ule i32 %x, %y
%r = select i1 %lt, i8 -1, i8 %ne
ret i8 %r
}