[llvm] r355221 - [InstCombine] move add after umin/umax
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Fri Mar 1 11:42:40 PST 2019
Author: spatel
Date: Fri Mar 1 11:42:40 2019
New Revision: 355221
URL: http://llvm.org/viewvc/llvm-project?rev=355221&view=rev
Log:
[InstCombine] move add after umin/umax
In the motivating cases from PR14613:
https://bugs.llvm.org/show_bug.cgi?id=14613
...moving the add enables us to narrow the
min/max which eliminates zext/trunc which
enables signficantly better vectorization.
But that bug is still not completely fixed.
https://rise4fun.com/Alive/5KQ
Name: umax
Pre: C1 u>= C0
%a = add nuw i8 %x, C0
%cond = icmp ugt i8 %a, C1
%r = select i1 %cond, i8 %a, i8 C1
=>
%c2 = icmp ugt i8 %x, C1-C0
%u2 = select i1 %c2, i8 %x, i8 C1-C0
%r = add nuw i8 %u2, C0
Name: umin
Pre: C1 u>= C0
%a = add nuw i32 %x, C0
%cond = icmp ult i32 %a, C1
%r = select i1 %cond, i32 %a, i32 C1
=>
%c2 = icmp ult i32 %x, C1-C0
%u2 = select i1 %c2, i32 %x, i32 C1-C0
%r = add nuw i32 %u2, C0
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp
llvm/trunk/test/Transforms/InstCombine/minmax-fold.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp?rev=355221&r1=355220&r2=355221&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp Fri Mar 1 11:42:40 2019
@@ -1563,6 +1563,30 @@ static Instruction *foldSelectCmpXchg(Se
return nullptr;
}
+static Instruction *moveAddAfterMinMax(SelectPatternFlavor SPF, Value *X,
+ Value *Y,
+ InstCombiner::BuilderTy &Builder) {
+ assert (SelectPatternResult::isMinOrMax(SPF) && "Expected min/max pattern");
+ bool IsUnsigned = SPF == SelectPatternFlavor::SPF_UMIN ||
+ SPF == SelectPatternFlavor::SPF_UMAX;
+ // TODO: If InstSimplify could fold all cases where C2 <= C1, we could change
+ // the constant value check to an assert.
+ Value *A;
+ const APInt *C1, *C2;
+ if (IsUnsigned && match(X, m_NUWAdd(m_Value(A), m_APInt(C1))) &&
+ match(Y, m_APInt(C2)) && C2->uge(*C1) && X->hasNUses(2)) {
+ // umin (add nuw A, C1), C2 --> add nuw (umin A, C2 - C1), C1
+ // umax (add nuw A, C1), C2 --> add nuw (umax A, C2 - C1), C1
+ Value *NewMinMax = createMinMax(Builder, SPF, A,
+ ConstantInt::get(X->getType(), *C2 - *C1));
+ return BinaryOperator::CreateNUW(BinaryOperator::Add, NewMinMax,
+ ConstantInt::get(X->getType(), *C1));
+ }
+ // TODO: Handle SMIN/SMAX (similar to unsigned, but the signed subtraction of
+ // the constants must not overflow).
+ return nullptr;
+}
+
/// Reduce a sequence of min/max with a common operand.
static Instruction *factorizeMinMaxTree(SelectPatternFlavor SPF, Value *LHS,
Value *RHS,
@@ -1962,6 +1986,9 @@ Instruction *InstCombiner::visitSelectIn
if (Instruction *I = moveNotAfterMinMax(RHS, LHS))
return I;
+ if (Instruction *I = moveAddAfterMinMax(SPF, LHS, RHS, Builder))
+ return I;
+
if (Instruction *I = factorizeMinMaxTree(SPF, LHS, RHS, Builder))
return I;
}
Modified: llvm/trunk/test/Transforms/InstCombine/minmax-fold.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/minmax-fold.ll?rev=355221&r1=355220&r2=355221&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/minmax-fold.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/minmax-fold.ll Fri Mar 1 11:42:40 2019
@@ -909,9 +909,9 @@ define float @not_min_of_min(i8 %i, floa
define i32 @add_umin(i32 %x) {
; CHECK-LABEL: @add_umin(
-; CHECK-NEXT: [[A:%.*]] = add nuw i32 [[X:%.*]], 15
-; CHECK-NEXT: [[C:%.*]] = icmp ult i32 [[A]], 42
-; CHECK-NEXT: [[R:%.*]] = select i1 [[C]], i32 [[A]], i32 42
+; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i32 [[X:%.*]], 27
+; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i32 [[X]], i32 27
+; CHECK-NEXT: [[R:%.*]] = add nuw nsw i32 [[TMP2]], 15
; CHECK-NEXT: ret i32 [[R]]
;
%a = add nuw i32 %x, 15
@@ -922,9 +922,8 @@ define i32 @add_umin(i32 %x) {
define i32 @add_umin_constant_limit(i32 %x) {
; CHECK-LABEL: @add_umin_constant_limit(
-; CHECK-NEXT: [[A:%.*]] = add nuw i32 [[X:%.*]], 41
-; CHECK-NEXT: [[C:%.*]] = icmp ult i32 [[A]], 42
-; CHECK-NEXT: [[R:%.*]] = select i1 [[C]], i32 [[A]], i32 42
+; CHECK-NEXT: [[TMP1:%.*]] = icmp eq i32 [[X:%.*]], 0
+; CHECK-NEXT: [[R:%.*]] = select i1 [[TMP1]], i32 41, i32 42
; CHECK-NEXT: ret i32 [[R]]
;
%a = add nuw i32 %x, 41
@@ -1008,9 +1007,9 @@ define i32 @add_umin_extra_use(i32 %x, i
define <2 x i16> @add_umin_vec(<2 x i16> %x) {
; CHECK-LABEL: @add_umin_vec(
-; CHECK-NEXT: [[A:%.*]] = add nuw <2 x i16> [[X:%.*]], <i16 15, i16 15>
-; CHECK-NEXT: [[C:%.*]] = icmp ult <2 x i16> [[A]], <i16 240, i16 240>
-; CHECK-NEXT: [[R:%.*]] = select <2 x i1> [[C]], <2 x i16> [[A]], <2 x i16> <i16 240, i16 240>
+; CHECK-NEXT: [[TMP1:%.*]] = icmp ult <2 x i16> [[X:%.*]], <i16 225, i16 225>
+; CHECK-NEXT: [[TMP2:%.*]] = select <2 x i1> [[TMP1]], <2 x i16> [[X]], <2 x i16> <i16 225, i16 225>
+; CHECK-NEXT: [[R:%.*]] = add nuw nsw <2 x i16> [[TMP2]], <i16 15, i16 15>
; CHECK-NEXT: ret <2 x i16> [[R]]
;
%a = add nuw <2 x i16> %x, <i16 15, i16 15>
@@ -1021,9 +1020,9 @@ define <2 x i16> @add_umin_vec(<2 x i16>
define i37 @add_umax(i37 %x) {
; CHECK-LABEL: @add_umax(
-; CHECK-NEXT: [[A:%.*]] = add nuw i37 [[X:%.*]], 5
-; CHECK-NEXT: [[C:%.*]] = icmp ugt i37 [[A]], 42
-; CHECK-NEXT: [[R:%.*]] = select i1 [[C]], i37 [[A]], i37 42
+; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt i37 [[X:%.*]], 37
+; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i37 [[X]], i37 37
+; CHECK-NEXT: [[R:%.*]] = add nuw i37 [[TMP2]], 5
; CHECK-NEXT: ret i37 [[R]]
;
%a = add nuw i37 %x, 5
@@ -1034,9 +1033,9 @@ define i37 @add_umax(i37 %x) {
define i37 @add_umax_constant_limit(i37 %x) {
; CHECK-LABEL: @add_umax_constant_limit(
-; CHECK-NEXT: [[A:%.*]] = add nuw i37 [[X:%.*]], 81
-; CHECK-NEXT: [[C:%.*]] = icmp ugt i37 [[A]], 82
-; CHECK-NEXT: [[R:%.*]] = select i1 [[C]], i37 [[A]], i37 82
+; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt i37 [[X:%.*]], 1
+; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i37 [[X]], i37 1
+; CHECK-NEXT: [[R:%.*]] = add nuw i37 [[TMP2]], 81
; CHECK-NEXT: ret i37 [[R]]
;
%a = add nuw i37 %x, 81
@@ -1050,9 +1049,7 @@ define i37 @add_umax_constant_limit(i37
define i37 @add_umax_simplify(i37 %x) {
; CHECK-LABEL: @add_umax_simplify(
-; CHECK-NEXT: [[A:%.*]] = add nuw i37 [[X:%.*]], 42
-; CHECK-NEXT: [[C:%.*]] = icmp ugt i37 [[A]], 42
-; CHECK-NEXT: [[R:%.*]] = select i1 [[C]], i37 [[A]], i37 42
+; CHECK-NEXT: [[R:%.*]] = add nuw i37 [[X:%.*]], 42
; CHECK-NEXT: ret i37 [[R]]
;
%a = add nuw i37 %x, 42
@@ -1124,9 +1121,9 @@ define i32 @add_umax_extra_use(i32 %x, i
define <2 x i33> @add_umax_vec(<2 x i33> %x) {
; CHECK-LABEL: @add_umax_vec(
-; CHECK-NEXT: [[A:%.*]] = add nuw <2 x i33> [[X:%.*]], <i33 5, i33 5>
-; CHECK-NEXT: [[C:%.*]] = icmp ugt <2 x i33> [[A]], <i33 240, i33 240>
-; CHECK-NEXT: [[R:%.*]] = select <2 x i1> [[C]], <2 x i33> [[A]], <2 x i33> <i33 240, i33 240>
+; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt <2 x i33> [[X:%.*]], <i33 235, i33 235>
+; CHECK-NEXT: [[TMP2:%.*]] = select <2 x i1> [[TMP1]], <2 x i33> [[X]], <2 x i33> <i33 235, i33 235>
+; CHECK-NEXT: [[R:%.*]] = add nuw <2 x i33> [[TMP2]], <i33 5, i33 5>
; CHECK-NEXT: ret <2 x i33> [[R]]
;
%a = add nuw <2 x i33> %x, <i33 5, i33 5>
@@ -1137,12 +1134,10 @@ define <2 x i33> @add_umax_vec(<2 x i33>
define i8 @PR14613_umin(i8 %x) {
; CHECK-LABEL: @PR14613_umin(
-; CHECK-NEXT: [[U4:%.*]] = zext i8 [[X:%.*]] to i32
-; CHECK-NEXT: [[U5:%.*]] = add nuw nsw i32 [[U4]], 15
-; CHECK-NEXT: [[U6:%.*]] = icmp ult i32 [[U5]], 255
-; CHECK-NEXT: [[U7:%.*]] = select i1 [[U6]], i32 [[U5]], i32 255
-; CHECK-NEXT: [[R:%.*]] = trunc i32 [[U7]] to i8
-; CHECK-NEXT: ret i8 [[R]]
+; 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: ret i8 [[U7]]
;
%u4 = zext i8 %x to i32
%u5 = add nuw nsw i32 %u4, 15
@@ -1154,12 +1149,10 @@ define i8 @PR14613_umin(i8 %x) {
define i8 @PR14613_umax(i8 %x) {
; CHECK-LABEL: @PR14613_umax(
-; CHECK-NEXT: [[U4:%.*]] = zext i8 [[X:%.*]] to i32
-; CHECK-NEXT: [[U5:%.*]] = add nuw nsw i32 [[U4]], 15
-; CHECK-NEXT: [[U6:%.*]] = icmp ugt i32 [[U5]], 255
-; CHECK-NEXT: [[U7:%.*]] = select i1 [[U6]], i32 [[U5]], i32 255
-; CHECK-NEXT: [[R:%.*]] = trunc i32 [[U7]] to i8
-; CHECK-NEXT: ret i8 [[R]]
+; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt i8 [[X:%.*]], -16
+; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i8 [[X]], i8 -16
+; CHECK-NEXT: [[U7:%.*]] = add nsw i8 [[TMP2]], 15
+; CHECK-NEXT: ret i8 [[U7]]
;
%u4 = zext i8 %x to i32
%u5 = add nuw nsw i32 %u4, 15
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