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-rw-r--r--llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp25
-rw-r--r--llvm/test/Transforms/InstCombine/minmax-fold.ll4
-rw-r--r--llvm/test/Transforms/InstCombine/saturating-add-sub.ll87
3 files changed, 94 insertions, 22 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
index 4b0199d8393..6d743a26098 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -1064,6 +1064,28 @@ static Instruction *canonicalizeLowbitMask(BinaryOperator &I,
return BinaryOperator::CreateNot(NotMask, I.getName());
}
+static Instruction *foldToUnsignedSaturatedAdd(BinaryOperator &I) {
+ assert(I.getOpcode() == Instruction::Add && "Expecting add instruction");
+ Type *Ty = I.getType();
+ auto getUAddSat = [&]() {
+ return Intrinsic::getDeclaration(I.getModule(), Intrinsic::uadd_sat, Ty);
+ };
+
+ // add (umin X, ~Y), Y --> uaddsat X, Y
+ Value *X, *Y;
+ if (match(&I, m_c_Add(m_c_UMin(m_Value(X), m_Not(m_Value(Y))),
+ m_Deferred(Y))))
+ return CallInst::Create(getUAddSat(), { X, Y });
+
+ // add (umin X, ~C), C --> uaddsat X, C
+ const APInt *C, *NotC;
+ if (match(&I, m_Add(m_UMin(m_Value(X), m_APInt(NotC)), m_APInt(C))) &&
+ *C == ~*NotC)
+ return CallInst::Create(getUAddSat(), { X, ConstantInt::get(Ty, *C) });
+
+ return nullptr;
+}
+
Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
if (Value *V = SimplifyAddInst(I.getOperand(0), I.getOperand(1),
I.hasNoSignedWrap(), I.hasNoUnsignedWrap(),
@@ -1266,6 +1288,9 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
if (Instruction *V = canonicalizeLowbitMask(I, Builder))
return V;
+ if (Instruction *SatAdd = foldToUnsignedSaturatedAdd(I))
+ return SatAdd;
+
return Changed ? &I : nullptr;
}
diff --git a/llvm/test/Transforms/InstCombine/minmax-fold.ll b/llvm/test/Transforms/InstCombine/minmax-fold.ll
index d312155c523..f68b62ad7d0 100644
--- a/llvm/test/Transforms/InstCombine/minmax-fold.ll
+++ b/llvm/test/Transforms/InstCombine/minmax-fold.ll
@@ -1134,9 +1134,7 @@ define <2 x i33> @add_umax_vec(<2 x i33> %x) {
define i8 @PR14613_umin(i8 %x) {
; CHECK-LABEL: @PR14613_umin(
-; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i8 [[X:%.*]], -16
-; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i8 [[X]], i8 -16
-; CHECK-NEXT: [[U7:%.*]] = add i8 [[TMP2]], 15
+; CHECK-NEXT: [[U7:%.*]] = call i8 @llvm.uadd.sat.i8(i8 [[X:%.*]], i8 15)
; CHECK-NEXT: ret i8 [[U7]]
;
%u4 = zext i8 %x to i32
diff --git a/llvm/test/Transforms/InstCombine/saturating-add-sub.ll b/llvm/test/Transforms/InstCombine/saturating-add-sub.ll
index c817b18abfc..4d0e722d5c8 100644
--- a/llvm/test/Transforms/InstCombine/saturating-add-sub.ll
+++ b/llvm/test/Transforms/InstCombine/saturating-add-sub.ll
@@ -1254,10 +1254,7 @@ declare <2 x i8> @get_v2i8()
define i32 @unsigned_sat_variable_using_min_add(i32 %x) {
; CHECK-LABEL: @unsigned_sat_variable_using_min_add(
; CHECK-NEXT: [[Y:%.*]] = call i32 @get_i32()
-; CHECK-NEXT: [[NOTY:%.*]] = xor i32 [[Y]], -1
-; CHECK-NEXT: [[C:%.*]] = icmp ugt i32 [[NOTY]], [[X:%.*]]
-; CHECK-NEXT: [[S:%.*]] = select i1 [[C]], i32 [[X]], i32 [[NOTY]]
-; CHECK-NEXT: [[R:%.*]] = add i32 [[S]], [[Y]]
+; CHECK-NEXT: [[R:%.*]] = call i32 @llvm.uadd.sat.i32(i32 [[X:%.*]], i32 [[Y]])
; CHECK-NEXT: ret i32 [[R]]
;
%y = call i32 @get_i32() ; thwart complexity-based canonicalization
@@ -1271,10 +1268,7 @@ define i32 @unsigned_sat_variable_using_min_add(i32 %x) {
define i32 @unsigned_sat_variable_using_min_commute_add(i32 %x) {
; CHECK-LABEL: @unsigned_sat_variable_using_min_commute_add(
; CHECK-NEXT: [[Y:%.*]] = call i32 @get_i32()
-; CHECK-NEXT: [[NOTY:%.*]] = xor i32 [[Y]], -1
-; CHECK-NEXT: [[C:%.*]] = icmp ugt i32 [[NOTY]], [[X:%.*]]
-; CHECK-NEXT: [[S:%.*]] = select i1 [[C]], i32 [[X]], i32 [[NOTY]]
-; CHECK-NEXT: [[R:%.*]] = add i32 [[Y]], [[S]]
+; CHECK-NEXT: [[R:%.*]] = call i32 @llvm.uadd.sat.i32(i32 [[X:%.*]], i32 [[Y]])
; CHECK-NEXT: ret i32 [[R]]
;
%y = call i32 @get_i32() ; thwart complexity-based canonicalization
@@ -1288,10 +1282,7 @@ define i32 @unsigned_sat_variable_using_min_commute_add(i32 %x) {
define <2 x i8> @unsigned_sat_variable_using_min_commute_select(<2 x i8> %x) {
; CHECK-LABEL: @unsigned_sat_variable_using_min_commute_select(
; CHECK-NEXT: [[Y:%.*]] = call <2 x i8> @get_v2i8()
-; CHECK-NEXT: [[NOTY:%.*]] = xor <2 x i8> [[Y]], <i8 -1, i8 -1>
-; CHECK-NEXT: [[C:%.*]] = icmp ult <2 x i8> [[NOTY]], [[X:%.*]]
-; CHECK-NEXT: [[S:%.*]] = select <2 x i1> [[C]], <2 x i8> [[NOTY]], <2 x i8> [[X]]
-; CHECK-NEXT: [[R:%.*]] = add <2 x i8> [[S]], [[Y]]
+; CHECK-NEXT: [[R:%.*]] = call <2 x i8> @llvm.uadd.sat.v2i8(<2 x i8> [[X:%.*]], <2 x i8> [[Y]])
; CHECK-NEXT: ret <2 x i8> [[R]]
;
%y = call <2 x i8> @get_v2i8() ; thwart complexity-based canonicalization
@@ -1305,10 +1296,7 @@ define <2 x i8> @unsigned_sat_variable_using_min_commute_select(<2 x i8> %x) {
define <2 x i8> @unsigned_sat_variable_using_min_commute_add_select(<2 x i8> %x) {
; CHECK-LABEL: @unsigned_sat_variable_using_min_commute_add_select(
; CHECK-NEXT: [[Y:%.*]] = call <2 x i8> @get_v2i8()
-; CHECK-NEXT: [[NOTY:%.*]] = xor <2 x i8> [[Y]], <i8 -1, i8 -1>
-; CHECK-NEXT: [[C:%.*]] = icmp ult <2 x i8> [[NOTY]], [[X:%.*]]
-; CHECK-NEXT: [[S:%.*]] = select <2 x i1> [[C]], <2 x i8> [[NOTY]], <2 x i8> [[X]]
-; CHECK-NEXT: [[R:%.*]] = add <2 x i8> [[Y]], [[S]]
+; CHECK-NEXT: [[R:%.*]] = call <2 x i8> @llvm.uadd.sat.v2i8(<2 x i8> [[X:%.*]], <2 x i8> [[Y]])
; CHECK-NEXT: ret <2 x i8> [[R]]
;
%y = call <2 x i8> @get_v2i8() ; thwart complexity-based canonicalization
@@ -1319,13 +1307,49 @@ define <2 x i8> @unsigned_sat_variable_using_min_commute_add_select(<2 x i8> %x)
ret <2 x i8> %r
}
+; Negative test
+
+define i32 @unsigned_sat_variable_using_wrong_min(i32 %x) {
+; CHECK-LABEL: @unsigned_sat_variable_using_wrong_min(
+; CHECK-NEXT: [[Y:%.*]] = call i32 @get_i32()
+; CHECK-NEXT: [[NOTY:%.*]] = xor i32 [[Y]], -1
+; CHECK-NEXT: [[C:%.*]] = icmp sgt i32 [[NOTY]], [[X:%.*]]
+; CHECK-NEXT: [[S:%.*]] = select i1 [[C]], i32 [[X]], i32 [[NOTY]]
+; CHECK-NEXT: [[R:%.*]] = add i32 [[Y]], [[S]]
+; CHECK-NEXT: ret i32 [[R]]
+;
+ %y = call i32 @get_i32() ; thwart complexity-based canonicalization
+ %noty = xor i32 %y, -1
+ %c = icmp slt i32 %x, %noty
+ %s = select i1 %c, i32 %x, i32 %noty
+ %r = add i32 %y, %s
+ ret i32 %r
+}
+
+; Negative test
+
+define i32 @unsigned_sat_variable_using_wrong_value(i32 %x, i32 %z) {
+; CHECK-LABEL: @unsigned_sat_variable_using_wrong_value(
+; CHECK-NEXT: [[Y:%.*]] = call i32 @get_i32()
+; CHECK-NEXT: [[NOTY:%.*]] = xor i32 [[Y]], -1
+; CHECK-NEXT: [[C:%.*]] = icmp ugt i32 [[NOTY]], [[X:%.*]]
+; CHECK-NEXT: [[S:%.*]] = select i1 [[C]], i32 [[X]], i32 [[NOTY]]
+; CHECK-NEXT: [[R:%.*]] = add i32 [[S]], [[Z:%.*]]
+; CHECK-NEXT: ret i32 [[R]]
+;
+ %y = call i32 @get_i32() ; thwart complexity-based canonicalization
+ %noty = xor i32 %y, -1
+ %c = icmp ult i32 %x, %noty
+ %s = select i1 %c, i32 %x, i32 %noty
+ %r = add i32 %z, %s
+ ret i32 %r
+}
+
; If we have a constant operand, there's no commutativity variation.
define i32 @unsigned_sat_constant_using_min(i32 %x) {
; CHECK-LABEL: @unsigned_sat_constant_using_min(
-; CHECK-NEXT: [[C:%.*]] = icmp ult i32 [[X:%.*]], 42
-; CHECK-NEXT: [[S:%.*]] = select i1 [[C]], i32 [[X]], i32 42
-; CHECK-NEXT: [[R:%.*]] = add nsw i32 [[S]], -43
+; CHECK-NEXT: [[R:%.*]] = call i32 @llvm.uadd.sat.i32(i32 [[X:%.*]], i32 -43)
; CHECK-NEXT: ret i32 [[R]]
;
%c = icmp ult i32 %x, 42
@@ -1334,3 +1358,28 @@ define i32 @unsigned_sat_constant_using_min(i32 %x) {
ret i32 %r
}
+define <2 x i32> @unsigned_sat_constant_using_min_splat(<2 x i32> %x) {
+; CHECK-LABEL: @unsigned_sat_constant_using_min_splat(
+; CHECK-NEXT: [[R:%.*]] = call <2 x i32> @llvm.uadd.sat.v2i32(<2 x i32> [[X:%.*]], <2 x i32> <i32 -15, i32 -15>)
+; CHECK-NEXT: ret <2 x i32> [[R]]
+;
+ %c = icmp ult <2 x i32> %x, <i32 14, i32 14>
+ %s = select <2 x i1> %c, <2 x i32> %x, <2 x i32> <i32 14, i32 14>
+ %r = add <2 x i32> %s, <i32 -15, i32 -15>
+ ret <2 x i32> %r
+}
+
+; Negative test
+
+define i32 @unsigned_sat_constant_using_min_wrong_constant(i32 %x) {
+; CHECK-LABEL: @unsigned_sat_constant_using_min_wrong_constant(
+; CHECK-NEXT: [[C:%.*]] = icmp ult i32 [[X:%.*]], 42
+; CHECK-NEXT: [[S:%.*]] = select i1 [[C]], i32 [[X]], i32 42
+; CHECK-NEXT: [[R:%.*]] = add nsw i32 [[S]], -42
+; CHECK-NEXT: ret i32 [[R]]
+;
+ %c = icmp ult i32 %x, 42
+ %s = select i1 %c, i32 %x, i32 42
+ %r = add i32 %s, -42
+ ret i32 %r
+}
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