[llvm] r340787 - [InstCombine] allow shuffle+binop canonicalization with widening shuffles
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Mon Aug 27 15:41:44 PDT 2018
Author: spatel
Date: Mon Aug 27 15:41:44 2018
New Revision: 340787
URL: http://llvm.org/viewvc/llvm-project?rev=340787&view=rev
Log:
[InstCombine] allow shuffle+binop canonicalization with widening shuffles
This lines up with the behavior of an existing transform where if both
operands of the binop are shuffled, we allow moving the binop before the
shuffle regardless of whether the shuffle changes the size of the vector.
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
llvm/trunk/test/Transforms/InstCombine/vec_shuffle.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp?rev=340787&r1=340786&r2=340787&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp Mon Aug 27 15:41:44 2018
@@ -1393,7 +1393,10 @@ Instruction *InstCombiner::foldShuffledB
if (match(&Inst, m_c_BinOp(
m_OneUse(m_ShuffleVector(m_Value(V1), m_Undef(), m_Constant(Mask))),
m_Constant(C))) &&
- V1->getType() == Inst.getType()) {
+ V1->getType()->getVectorNumElements() <= VWidth) {
+ assert(Inst.getType()->getScalarType() == V1->getType()->getScalarType() &&
+ "Shuffle should not change scalar type");
+ unsigned V1Width = V1->getType()->getVectorNumElements();
// Find constant NewC that has property:
// shuffle(NewC, ShMask) = C
// If such constant does not exist (example: ShMask=<0,0> and C=<1,2>)
@@ -1402,14 +1405,21 @@ Instruction *InstCombiner::foldShuffledB
SmallVector<int, 16> ShMask;
ShuffleVectorInst::getShuffleMask(Mask, ShMask);
SmallVector<Constant *, 16>
- NewVecC(VWidth, UndefValue::get(C->getType()->getScalarType()));
+ NewVecC(V1Width, UndefValue::get(C->getType()->getScalarType()));
bool MayChange = true;
for (unsigned I = 0; I < VWidth; ++I) {
if (ShMask[I] >= 0) {
- assert(ShMask[I] < (int)VWidth);
+ assert(ShMask[I] < (int)VWidth && "Not expecting narrowing shuffle");
Constant *CElt = C->getAggregateElement(I);
Constant *NewCElt = NewVecC[ShMask[I]];
- if (!CElt || (!isa<UndefValue>(NewCElt) && NewCElt != CElt)) {
+ // Bail out if:
+ // 1. The constant vector contains a constant expression.
+ // 2. The shuffle needs an element of the constant vector that can't
+ // be mapped to a new constant vector.
+ // 3. This is a widening shuffle that copies elements of V1 into the
+ // extended elements (extending with undef is allowed).
+ if (!CElt || (!isa<UndefValue>(NewCElt) && NewCElt != CElt) ||
+ I >= V1Width) {
MayChange = false;
break;
}
Modified: llvm/trunk/test/Transforms/InstCombine/vec_shuffle.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/vec_shuffle.ll?rev=340787&r1=340786&r2=340787&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/vec_shuffle.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/vec_shuffle.ll Mon Aug 27 15:41:44 2018
@@ -474,12 +474,12 @@ define <2 x float> @fmul_const_invalid_c
ret <2 x float> %r
}
-; TODO: Reduce the width of the binop by moving it ahead of a shuffle.
+; Reduce the width of the binop by moving it ahead of a shuffle.
define <4 x i8> @widening_shuffle_add_1(<2 x i8> %x) {
; CHECK-LABEL: @widening_shuffle_add_1(
-; CHECK-NEXT: [[WIDEX:%.*]] = shufflevector <2 x i8> [[X:%.*]], <2 x i8> undef, <4 x i32> <i32 0, i32 1, i32 undef, i32 undef>
-; CHECK-NEXT: [[R:%.*]] = add <4 x i8> [[WIDEX]], <i8 42, i8 43, i8 44, i8 45>
+; CHECK-NEXT: [[TMP1:%.*]] = add <2 x i8> [[X:%.*]], <i8 42, i8 43>
+; CHECK-NEXT: [[R:%.*]] = shufflevector <2 x i8> [[TMP1]], <2 x i8> undef, <4 x i32> <i32 0, i32 1, i32 undef, i32 undef>
; CHECK-NEXT: ret <4 x i8> [[R]]
;
%widex = shufflevector <2 x i8> %x, <2 x i8> undef, <4 x i32> <i32 0, i32 1, i32 undef, i32 undef>
@@ -487,12 +487,12 @@ define <4 x i8> @widening_shuffle_add_1(
ret <4 x i8> %r
}
-; TODO: Reduce the width of the binop by moving it ahead of a shuffle.
+; Reduce the width of the binop by moving it ahead of a shuffle.
define <4 x i8> @widening_shuffle_add_2(<2 x i8> %x) {
; CHECK-LABEL: @widening_shuffle_add_2(
-; CHECK-NEXT: [[WIDEX:%.*]] = shufflevector <2 x i8> [[X:%.*]], <2 x i8> undef, <4 x i32> <i32 1, i32 0, i32 undef, i32 undef>
-; CHECK-NEXT: [[R:%.*]] = add <4 x i8> [[WIDEX]], <i8 42, i8 43, i8 44, i8 45>
+; CHECK-NEXT: [[TMP1:%.*]] = add <2 x i8> [[X:%.*]], <i8 43, i8 42>
+; CHECK-NEXT: [[R:%.*]] = shufflevector <2 x i8> [[TMP1]], <2 x i8> undef, <4 x i32> <i32 1, i32 0, i32 undef, i32 undef>
; CHECK-NEXT: ret <4 x i8> [[R]]
;
%widex = shufflevector <2 x i8> %x, <2 x i8> undef, <4 x i32> <i32 1, i32 0, i32 undef, i32 undef>
@@ -500,7 +500,7 @@ define <4 x i8> @widening_shuffle_add_2(
ret <4 x i8> %r
}
-; Widening shuffles have the same mask/constant constraint as non-size-changing shuffles.
+; Negative test - widening shuffles have the same mask/constant constraint as non-size-changing shuffles.
define <4 x i8> @widening_shuffle_add_invalid_constant(<2 x i8> %x) {
; CHECK-LABEL: @widening_shuffle_add_invalid_constant(
@@ -513,7 +513,7 @@ define <4 x i8> @widening_shuffle_add_in
ret <4 x i8> %r
}
-; And widening shuffles have an additional constraint - they must not extend with anything but undefs.
+; Negative test - widening shuffles have an additional constraint: they must not extend with anything but undefs.
define <4 x i8> @widening_shuffle_add_invalid_mask(<2 x i8> %x) {
; CHECK-LABEL: @widening_shuffle_add_invalid_mask(
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