[IR] add shuffle queries for identity extend/extract
This was one of the potential follow-ups suggested in D48236,
and these will be used to make matching the patterns in PR38691 cleaner:
https://bugs.llvm.org/show_bug.cgi?id=38691
About the vocabulary: in the DAG, these would be concat_vector with an
undef operand or extract_subvector. Alternate names are discussed in the
review, but I think these are familiar/good enough to proceed. Once we
have uses of them in code, we might adjust if there are better options.
https://reviews.llvm.org/D51392
llvm-svn: 341075
diff --git a/llvm/include/llvm/IR/Instructions.h b/llvm/include/llvm/IR/Instructions.h
index 140a6f20..dea7fcd 100644
--- a/llvm/include/llvm/IR/Instructions.h
+++ b/llvm/include/llvm/IR/Instructions.h
@@ -2456,7 +2456,7 @@
}
/// Return true if this shuffle returns a vector with a different number of
- /// elements than its source elements.
+ /// elements than its source vectors.
/// Example: shufflevector <4 x n> A, <4 x n> B, <1,2>
bool changesLength() const {
unsigned NumSourceElts = Op<0>()->getType()->getVectorNumElements();
@@ -2497,15 +2497,22 @@
return isIdentityMask(MaskAsInts);
}
- /// Return true if this shuffle mask chooses elements from exactly one source
+ /// Return true if this shuffle chooses elements from exactly one source
/// vector without lane crossings and does not change the number of elements
/// from its input vectors.
/// Example: shufflevector <4 x n> A, <4 x n> B, <4,undef,6,undef>
- /// TODO: Optionally allow length-changing shuffles.
bool isIdentity() const {
return !changesLength() && isIdentityMask(getShuffleMask());
}
+ /// Return true if this shuffle lengthens exactly one source vector with
+ /// undefs in the high elements.
+ bool isIdentityWithPadding() const;
+
+ /// Return true if this shuffle extracts the first N elements of exactly one
+ /// source vector.
+ bool isIdentityWithExtract() const;
+
/// Return true if this shuffle mask chooses elements from its source vectors
/// without lane crossings. A shuffle using this mask would be
/// equivalent to a vector select with a constant condition operand.
diff --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
index 1a2752d..2bf9f0b 100644
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -1660,17 +1660,17 @@
}
}
-bool ShuffleVectorInst::isSingleSourceMask(ArrayRef<int> Mask) {
+static bool isSingleSourceMaskImpl(ArrayRef<int> Mask, int NumOpElts) {
assert(!Mask.empty() && "Shuffle mask must contain elements");
bool UsesLHS = false;
bool UsesRHS = false;
- for (int i = 0, NumElts = Mask.size(); i < NumElts; ++i) {
+ for (int i = 0, NumMaskElts = Mask.size(); i < NumMaskElts; ++i) {
if (Mask[i] == -1)
continue;
- assert(Mask[i] >= 0 && Mask[i] < (NumElts * 2) &&
+ assert(Mask[i] >= 0 && Mask[i] < (NumOpElts * 2) &&
"Out-of-bounds shuffle mask element");
- UsesLHS |= (Mask[i] < NumElts);
- UsesRHS |= (Mask[i] >= NumElts);
+ UsesLHS |= (Mask[i] < NumOpElts);
+ UsesRHS |= (Mask[i] >= NumOpElts);
if (UsesLHS && UsesRHS)
return false;
}
@@ -1678,18 +1678,30 @@
return true;
}
-bool ShuffleVectorInst::isIdentityMask(ArrayRef<int> Mask) {
- if (!isSingleSourceMask(Mask))
+bool ShuffleVectorInst::isSingleSourceMask(ArrayRef<int> Mask) {
+ // We don't have vector operand size information, so assume operands are the
+ // same size as the mask.
+ return isSingleSourceMaskImpl(Mask, Mask.size());
+}
+
+static bool isIdentityMaskImpl(ArrayRef<int> Mask, int NumOpElts) {
+ if (!isSingleSourceMaskImpl(Mask, NumOpElts))
return false;
- for (int i = 0, NumElts = Mask.size(); i < NumElts; ++i) {
+ for (int i = 0, NumMaskElts = Mask.size(); i < NumMaskElts; ++i) {
if (Mask[i] == -1)
continue;
- if (Mask[i] != i && Mask[i] != (NumElts + i))
+ if (Mask[i] != i && Mask[i] != (NumOpElts + i))
return false;
}
return true;
}
+bool ShuffleVectorInst::isIdentityMask(ArrayRef<int> Mask) {
+ // We don't have vector operand size information, so assume operands are the
+ // same size as the mask.
+ return isIdentityMaskImpl(Mask, Mask.size());
+}
+
bool ShuffleVectorInst::isReverseMask(ArrayRef<int> Mask) {
if (!isSingleSourceMask(Mask))
return false;
@@ -1761,6 +1773,33 @@
return true;
}
+bool ShuffleVectorInst::isIdentityWithPadding() const {
+ int NumOpElts = Op<0>()->getType()->getVectorNumElements();
+ int NumMaskElts = getType()->getVectorNumElements();
+ if (NumMaskElts <= NumOpElts)
+ return false;
+
+ // The first part of the mask must choose elements from exactly 1 source op.
+ ArrayRef<int> Mask = getShuffleMask();
+ if (!isIdentityMaskImpl(Mask, NumOpElts))
+ return false;
+
+ // All extending must be with undef elements.
+ for (int i = NumOpElts; i < NumMaskElts; ++i)
+ if (Mask[i] != -1)
+ return false;
+
+ return true;
+}
+
+bool ShuffleVectorInst::isIdentityWithExtract() const {
+ int NumOpElts = Op<0>()->getType()->getVectorNumElements();
+ int NumMaskElts = getType()->getVectorNumElements();
+ if (NumMaskElts >= NumOpElts)
+ return false;
+
+ return isIdentityMaskImpl(getShuffleMask(), NumOpElts);
+}
//===----------------------------------------------------------------------===//
// InsertValueInst Class
diff --git a/llvm/unittests/IR/InstructionsTest.cpp b/llvm/unittests/IR/InstructionsTest.cpp
index 6bac596..d153f99 100644
--- a/llvm/unittests/IR/InstructionsTest.cpp
+++ b/llvm/unittests/IR/InstructionsTest.cpp
@@ -837,6 +837,78 @@
EXPECT_TRUE(ShuffleVectorInst::isTransposeMask(ConstantVector::get({C1, C5, C3, C7})));
EXPECT_TRUE(ShuffleVectorInst::isTransposeMask(ConstantVector::get({C1, C3})));
+
+ // Identity with undef elts.
+ ShuffleVectorInst *Id1 = new ShuffleVectorInst(ConstantVector::get({C0, C1, C3, C3}),
+ ConstantVector::get({C0, C1, C2, C3}),
+ ConstantVector::get({C0, C1, CU, CU}));
+ EXPECT_TRUE(Id1->isIdentity());
+ EXPECT_FALSE(Id1->isIdentityWithPadding());
+ EXPECT_FALSE(Id1->isIdentityWithExtract());
+ delete Id1;
+
+ // Result has less elements than operands.
+ ShuffleVectorInst *Id2 = new ShuffleVectorInst(ConstantVector::get({C0, C1, C2, C3}),
+ ConstantVector::get({C0, C1, C2, C3}),
+ ConstantVector::get({C0, C1, C2}));
+ EXPECT_FALSE(Id2->isIdentity());
+ EXPECT_FALSE(Id2->isIdentityWithPadding());
+ EXPECT_TRUE(Id2->isIdentityWithExtract());
+ delete Id2;
+
+ // Result has less elements than operands; choose from Op1.
+ ShuffleVectorInst *Id3 = new ShuffleVectorInst(ConstantVector::get({C0, C1, C2, C3}),
+ ConstantVector::get({C0, C1, C2, C3}),
+ ConstantVector::get({C4, CU, C6}));
+ EXPECT_FALSE(Id3->isIdentity());
+ EXPECT_FALSE(Id3->isIdentityWithPadding());
+ EXPECT_TRUE(Id3->isIdentityWithExtract());
+ delete Id3;
+
+ // Result has less elements than operands; choose from Op0 and Op1 is not identity.
+ ShuffleVectorInst *Id4 = new ShuffleVectorInst(ConstantVector::get({C0, C1, C2, C3}),
+ ConstantVector::get({C0, C1, C2, C3}),
+ ConstantVector::get({C4, C1, C6}));
+ EXPECT_FALSE(Id4->isIdentity());
+ EXPECT_FALSE(Id4->isIdentityWithPadding());
+ EXPECT_FALSE(Id4->isIdentityWithExtract());
+ delete Id4;
+
+ // Result has more elements than operands, and extra elements are undef.
+ ShuffleVectorInst *Id5 = new ShuffleVectorInst(ConstantVector::get({C0, C1, C2, C3}),
+ ConstantVector::get({C0, C1, C2, C3}),
+ ConstantVector::get({CU, C1, C2, C3, CU, CU}));
+ EXPECT_FALSE(Id5->isIdentity());
+ EXPECT_TRUE(Id5->isIdentityWithPadding());
+ EXPECT_FALSE(Id5->isIdentityWithExtract());
+ delete Id5;
+
+ // Result has more elements than operands, and extra elements are undef; choose from Op1.
+ ShuffleVectorInst *Id6 = new ShuffleVectorInst(ConstantVector::get({C0, C1, C2, C3}),
+ ConstantVector::get({C0, C1, C2, C3}),
+ ConstantVector::get({C4, C5, C6, CU, CU, CU}));
+ EXPECT_FALSE(Id6->isIdentity());
+ EXPECT_TRUE(Id6->isIdentityWithPadding());
+ EXPECT_FALSE(Id6->isIdentityWithExtract());
+ delete Id6;
+
+ // Result has more elements than operands, but extra elements are not undef.
+ ShuffleVectorInst *Id7 = new ShuffleVectorInst(ConstantVector::get({C0, C1, C2, C3}),
+ ConstantVector::get({C0, C1, C2, C3}),
+ ConstantVector::get({C0, C1, C2, C3, CU, C1}));
+ EXPECT_FALSE(Id7->isIdentity());
+ EXPECT_FALSE(Id7->isIdentityWithPadding());
+ EXPECT_FALSE(Id7->isIdentityWithExtract());
+ delete Id7;
+
+ // Result has more elements than operands; choose from Op0 and Op1 is not identity.
+ ShuffleVectorInst *Id8 = new ShuffleVectorInst(ConstantVector::get({C0, C1, C2, C3}),
+ ConstantVector::get({C0, C1, C2, C3}),
+ ConstantVector::get({C4, CU, C2, C3, CU, CU}));
+ EXPECT_FALSE(Id8->isIdentity());
+ EXPECT_FALSE(Id8->isIdentityWithPadding());
+ EXPECT_FALSE(Id8->isIdentityWithExtract());
+ delete Id8;
}
TEST(InstructionsTest, SkipDebug) {