[llvm] [GISel] Add support for scalable vectors in getGCDType (PR #80307)
Michael Maitland via llvm-commits
llvm-commits at lists.llvm.org
Tue Feb 6 18:02:40 PST 2024
https://github.com/michaelmaitland updated https://github.com/llvm/llvm-project/pull/80307
>From 5d37cc38cab323859cc3b50dd1b4a89e473ca765 Mon Sep 17 00:00:00 2001
From: Michael Maitland <michaeltmaitland at gmail.com>
Date: Wed, 31 Jan 2024 11:51:26 -0800
Subject: [PATCH 1/5] [GISel] Add support for scalable vectors in getGCDType
This function can be called from buildCopyToRegs where at least one of the types
is a scalable vector type. This function crashed because it did not know
how to handle scalable vector types.
This patch extends the functionality of getGCDType to handle when at
least one of the types is a scalable vector. getGCDType between a fixed
and scalable vector is not implemented since the docstring of the
function explains that getGCDType is used to build MERGE/UNMERGE
instructions and we will never build a MERGE/UNMERGE between fixed and scalable
vectors.
---
llvm/include/llvm/CodeGen/GlobalISel/Utils.h | 5 +-
llvm/lib/CodeGen/GlobalISel/Utils.cpp | 79 +++++++++++--------
.../CodeGen/GlobalISel/GISelUtilsTest.cpp | 56 +++++++++++++
3 files changed, 107 insertions(+), 33 deletions(-)
diff --git a/llvm/include/llvm/CodeGen/GlobalISel/Utils.h b/llvm/include/llvm/CodeGen/GlobalISel/Utils.h
index c96e4217d21f05..f8900f3434ccaa 100644
--- a/llvm/include/llvm/CodeGen/GlobalISel/Utils.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/Utils.h
@@ -368,7 +368,10 @@ LLT getCoverTy(LLT OrigTy, LLT TargetTy);
/// If these are vectors with different element types, this will try to produce
/// a vector with a compatible total size, but the element type of \p OrigTy. If
/// this can't be satisfied, this will produce a scalar smaller than the
-/// original vector elements.
+/// original vector elements. It is an error to call this function where
+/// one argument is a fixed vector and the other is a scalable vector, since it
+/// is illegal to build a G_{MERGE|UNMERGE}_VALUES between fixed and scalable
+/// vectors.
///
/// In the worst case, this returns LLT::scalar(1)
LLVM_READNONE
diff --git a/llvm/lib/CodeGen/GlobalISel/Utils.cpp b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
index dd99381093b6ab..13d856e079f23c 100644
--- a/llvm/lib/CodeGen/GlobalISel/Utils.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
@@ -1159,45 +1159,60 @@ LLT llvm::getCoverTy(LLT OrigTy, LLT TargetTy) {
}
LLT llvm::getGCDType(LLT OrigTy, LLT TargetTy) {
- const unsigned OrigSize = OrigTy.getSizeInBits();
- const unsigned TargetSize = TargetTy.getSizeInBits();
-
- if (OrigSize == TargetSize)
+ if (OrigTy.getSizeInBits() == TargetTy.getSizeInBits())
return OrigTy;
- if (OrigTy.isVector()) {
+ if (OrigTy.isVector() && TargetTy.isVector()) {
LLT OrigElt = OrigTy.getElementType();
- if (TargetTy.isVector()) {
- LLT TargetElt = TargetTy.getElementType();
- if (OrigElt.getSizeInBits() == TargetElt.getSizeInBits()) {
- int GCD = std::gcd(OrigTy.getNumElements(), TargetTy.getNumElements());
- return LLT::scalarOrVector(ElementCount::getFixed(GCD), OrigElt);
- }
- } else {
- // If the source is a vector of pointers, return a pointer element.
- if (OrigElt.getSizeInBits() == TargetSize)
- return OrigElt;
- }
-
- unsigned GCD = std::gcd(OrigSize, TargetSize);
- if (GCD == OrigElt.getSizeInBits())
- return OrigElt;
+ LLT TargetElt = TargetTy.getElementType();
- // If we can't produce the original element type, we have to use a smaller
- // scalar.
- if (GCD < OrigElt.getSizeInBits())
- return LLT::scalar(GCD);
- return LLT::fixed_vector(GCD / OrigElt.getSizeInBits(), OrigElt);
+ // TODO: The docstring for this function says the intention is to use this
+ // function to build MERGE/UNMERGE instructions. It won't be the case that
+ // we generate a MERGE/UNMERGE between fixed and scalable vector types. We
+ // could implement getGCDType between the two in the future if there was a
+ // need, but it is not worth it now as this function should not be used in
+ // that way.
+ if ((OrigTy.isScalableVector() && TargetTy.isFixedVector()) ||
+ (OrigTy.isFixedVector() && TargetTy.isScalableVector()))
+ llvm_unreachable(
+ "getGCDType not implemented between fixed and scalable vectors.");
+
+ unsigned GCD = std::gcd(OrigTy.getElementCount().getKnownMinValue() *
+ OrigElt.getSizeInBits().getFixedValue(),
+ TargetTy.getElementCount().getKnownMinValue() *
+ TargetElt.getSizeInBits().getFixedValue());
+ if (GCD == OrigElt.getSizeInBits())
+ return LLT::scalarOrVector(ElementCount::get(1, OrigTy.isScalable()),
+ OrigElt);
+
+ // Cannot produce original element type, but both have vscale in common.
+ if (GCD < OrigElt.getSizeInBits())
+ return LLT::scalarOrVector(ElementCount::get(1, OrigTy.isScalable()),
+ GCD);
+
+ return LLT::vector(
+ ElementCount::get(GCD / OrigElt.getSizeInBits().getFixedValue(),
+ OrigTy.isScalable()),
+ OrigElt);
}
- if (TargetTy.isVector()) {
- // Try to preserve the original element type.
- LLT TargetElt = TargetTy.getElementType();
- if (TargetElt.getSizeInBits() == OrigSize)
- return OrigTy;
- }
+ // If one type is vector and the element size matches the scalar size, then
+ // the gcd is the scalar type.
+ if (OrigTy.isVector() &&
+ OrigTy.getElementType().getSizeInBits() == TargetTy.getSizeInBits())
+ return OrigTy.getElementType();
+ if (TargetTy.isVector() &&
+ TargetTy.getElementType().getSizeInBits() == OrigTy.getSizeInBits())
+ return OrigTy;
- unsigned GCD = std::gcd(OrigSize, TargetSize);
+ // At this point, both types are either scalars of different type or one is a
+ // vector and one is a scalar. If both types are scalars, the GCD type is the
+ // GCD between the two scalar sizes. If one is vector and one is scalar, then
+ // the GCD type is the GCD between the scalar and the vector element size.
+ LLT OrigScalar = OrigTy.isVector() ? OrigTy.getElementType() : OrigTy;
+ LLT TargetScalar = TargetTy.isVector() ? TargetTy.getElementType() : TargetTy;
+ unsigned GCD = std::gcd(OrigScalar.getSizeInBits().getFixedValue(),
+ TargetScalar.getSizeInBits().getFixedValue());
return LLT::scalar(GCD);
}
diff --git a/llvm/unittests/CodeGen/GlobalISel/GISelUtilsTest.cpp b/llvm/unittests/CodeGen/GlobalISel/GISelUtilsTest.cpp
index 92bd0a36b82b48..1ff7fd956d015d 100644
--- a/llvm/unittests/CodeGen/GlobalISel/GISelUtilsTest.cpp
+++ b/llvm/unittests/CodeGen/GlobalISel/GISelUtilsTest.cpp
@@ -183,6 +183,62 @@ TEST(GISelUtilsTest, getGCDType) {
EXPECT_EQ(LLT::scalar(4), getGCDType(LLT::fixed_vector(3, 4), S8));
EXPECT_EQ(LLT::scalar(4), getGCDType(S8, LLT::fixed_vector(3, 4)));
+
+ // Scalable -> Scalable
+ EXPECT_EQ(NXV1S1, getGCDType(NXV1S1, NXV1S32));
+ EXPECT_EQ(NXV1S32, getGCDType(NXV1S64, NXV1S32));
+ EXPECT_EQ(NXV1S32, getGCDType(NXV1S32, NXV1S64));
+ EXPECT_EQ(NXV1P0, getGCDType(NXV1P0, NXV1S64));
+ EXPECT_EQ(NXV1S64, getGCDType(NXV1S64, NXV1P0));
+
+ EXPECT_EQ(NXV4S1, getGCDType(NXV4S1, NXV4S32));
+ EXPECT_EQ(NXV2S64, getGCDType(NXV4S64, NXV4S32));
+ EXPECT_EQ(NXV4S32, getGCDType(NXV4S32, NXV4S64));
+ EXPECT_EQ(NXV4P0, getGCDType(NXV4P0, NXV4S64));
+ EXPECT_EQ(NXV4S64, getGCDType(NXV4S64, NXV4P0));
+
+ EXPECT_EQ(NXV4S1, getGCDType(NXV4S1, NXV2S32));
+ EXPECT_EQ(NXV1S64, getGCDType(NXV4S64, NXV2S32));
+ EXPECT_EQ(NXV4S32, getGCDType(NXV4S32, NXV2S64));
+ EXPECT_EQ(NXV2P0, getGCDType(NXV4P0, NXV2S64));
+ EXPECT_EQ(NXV2S64, getGCDType(NXV4S64, NXV2P0));
+
+ EXPECT_EQ(NXV2S1, getGCDType(NXV2S1, NXV4S32));
+ EXPECT_EQ(NXV2S64, getGCDType(NXV2S64, NXV4S32));
+ EXPECT_EQ(NXV2S32, getGCDType(NXV2S32, NXV4S64));
+ EXPECT_EQ(NXV2P0, getGCDType(NXV2P0, NXV4S64));
+ EXPECT_EQ(NXV2S64, getGCDType(NXV2S64, NXV4P0));
+
+ EXPECT_EQ(NXV1S1, getGCDType(NXV3S1, NXV4S32));
+ EXPECT_EQ(NXV1S64, getGCDType(NXV3S64, NXV4S32));
+ EXPECT_EQ(NXV1S32, getGCDType(NXV3S32, NXV4S64));
+ EXPECT_EQ(NXV1P0, getGCDType(NXV3P0, NXV4S64));
+ EXPECT_EQ(NXV1S64, getGCDType(NXV3S64, NXV4P0));
+
+ EXPECT_EQ(NXV1S1, getGCDType(NXV3S1, NXV4S1));
+ EXPECT_EQ(NXV1S32, getGCDType(NXV3S32, NXV4S32));
+ EXPECT_EQ(NXV1S64, getGCDType(NXV3S64, NXV4S64));
+ EXPECT_EQ(NXV1P0, getGCDType(NXV3P0, NXV4P0));
+
+ // Scalable, Scalar
+
+ EXPECT_EQ(S1, getGCDType(NXV1S1, S1));
+ EXPECT_EQ(S1, getGCDType(NXV1S1, S32));
+ EXPECT_EQ(S1, getGCDType(NXV1S32, S1));
+ EXPECT_EQ(S32, getGCDType(NXV1S32, S32));
+ EXPECT_EQ(S32, getGCDType(NXV1S32, S64));
+ EXPECT_EQ(S1, getGCDType(NXV2S32, S1));
+ EXPECT_EQ(S32, getGCDType(NXV2S32, S32));
+ EXPECT_EQ(S32, getGCDType(NXV2S32, S64));
+
+ EXPECT_EQ(S1, getGCDType(S1, NXV1S1));
+ EXPECT_EQ(S1, getGCDType(S32, NXV1S1));
+ EXPECT_EQ(S1, getGCDType(S1, NXV1S32));
+ EXPECT_EQ(S32, getGCDType(S32, NXV1S32));
+ EXPECT_EQ(S32, getGCDType(S64, NXV1S32));
+ EXPECT_EQ(S1, getGCDType(S1, NXV2S32));
+ EXPECT_EQ(S32, getGCDType(S32, NXV2S32));
+ EXPECT_EQ(S32, getGCDType(S64, NXV2S32));
}
TEST(GISelUtilsTest, getLCMType) {
>From fa01fda60673cac0638ca9504801d5f450e62c0e Mon Sep 17 00:00:00 2001
From: Michael Maitland <michaeltmaitland at gmail.com>
Date: Thu, 1 Feb 2024 08:36:18 -0800
Subject: [PATCH 2/5] fixup! clang-format
---
llvm/lib/CodeGen/GlobalISel/Utils.cpp | 34 +++++++++++++--------------
1 file changed, 17 insertions(+), 17 deletions(-)
diff --git a/llvm/lib/CodeGen/GlobalISel/Utils.cpp b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
index 13d856e079f23c..535f6c4803270b 100644
--- a/llvm/lib/CodeGen/GlobalISel/Utils.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
@@ -1177,23 +1177,23 @@ LLT llvm::getGCDType(LLT OrigTy, LLT TargetTy) {
llvm_unreachable(
"getGCDType not implemented between fixed and scalable vectors.");
- unsigned GCD = std::gcd(OrigTy.getElementCount().getKnownMinValue() *
- OrigElt.getSizeInBits().getFixedValue(),
- TargetTy.getElementCount().getKnownMinValue() *
- TargetElt.getSizeInBits().getFixedValue());
- if (GCD == OrigElt.getSizeInBits())
- return LLT::scalarOrVector(ElementCount::get(1, OrigTy.isScalable()),
- OrigElt);
-
- // Cannot produce original element type, but both have vscale in common.
- if (GCD < OrigElt.getSizeInBits())
- return LLT::scalarOrVector(ElementCount::get(1, OrigTy.isScalable()),
- GCD);
-
- return LLT::vector(
- ElementCount::get(GCD / OrigElt.getSizeInBits().getFixedValue(),
- OrigTy.isScalable()),
- OrigElt);
+ unsigned GCD = std::gcd(OrigTy.getElementCount().getKnownMinValue() *
+ OrigElt.getSizeInBits().getFixedValue(),
+ TargetTy.getElementCount().getKnownMinValue() *
+ TargetElt.getSizeInBits().getFixedValue());
+ if (GCD == OrigElt.getSizeInBits())
+ return LLT::scalarOrVector(ElementCount::get(1, OrigTy.isScalable()),
+ OrigElt);
+
+ // Cannot produce original element type, but both have vscale in common.
+ if (GCD < OrigElt.getSizeInBits())
+ return LLT::scalarOrVector(ElementCount::get(1, OrigTy.isScalable()),
+ GCD);
+
+ return LLT::vector(
+ ElementCount::get(GCD / OrigElt.getSizeInBits().getFixedValue(),
+ OrigTy.isScalable()),
+ OrigElt);
}
// If one type is vector and the element size matches the scalar size, then
>From 4866dd65aa688ba58330b816a91a4a391209d6ef Mon Sep 17 00:00:00 2001
From: Michael Maitland <michaeltmaitland at gmail.com>
Date: Mon, 5 Feb 2024 10:42:28 -0500
Subject: [PATCH 3/5] fixup! use getScalarType
Co-authored-by: Matt Arsenault <arsenm2 at gmail.com>
---
llvm/lib/CodeGen/GlobalISel/Utils.cpp | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/llvm/lib/CodeGen/GlobalISel/Utils.cpp b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
index 535f6c4803270b..b5476d493f31e6 100644
--- a/llvm/lib/CodeGen/GlobalISel/Utils.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
@@ -1209,8 +1209,8 @@ LLT llvm::getGCDType(LLT OrigTy, LLT TargetTy) {
// vector and one is a scalar. If both types are scalars, the GCD type is the
// GCD between the two scalar sizes. If one is vector and one is scalar, then
// the GCD type is the GCD between the scalar and the vector element size.
- LLT OrigScalar = OrigTy.isVector() ? OrigTy.getElementType() : OrigTy;
- LLT TargetScalar = TargetTy.isVector() ? TargetTy.getElementType() : TargetTy;
+ LLT OrigScalar = OrigTy.getScalarType();
+ LLT TargetScalar = TargetTy.getScalarType();
unsigned GCD = std::gcd(OrigScalar.getSizeInBits().getFixedValue(),
TargetScalar.getSizeInBits().getFixedValue());
return LLT::scalar(GCD);
>From e9e22e086536d34d2a4c7ba4728fc3592e889266 Mon Sep 17 00:00:00 2001
From: Michael Maitland <michaeltmaitland at gmail.com>
Date: Tue, 6 Feb 2024 07:06:49 -0800
Subject: [PATCH 4/5] fixup! simplify known min size calculation
---
llvm/lib/CodeGen/GlobalISel/Utils.cpp | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/llvm/lib/CodeGen/GlobalISel/Utils.cpp b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
index b5476d493f31e6..503289ef679f00 100644
--- a/llvm/lib/CodeGen/GlobalISel/Utils.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
@@ -1177,10 +1177,8 @@ LLT llvm::getGCDType(LLT OrigTy, LLT TargetTy) {
llvm_unreachable(
"getGCDType not implemented between fixed and scalable vectors.");
- unsigned GCD = std::gcd(OrigTy.getElementCount().getKnownMinValue() *
- OrigElt.getSizeInBits().getFixedValue(),
- TargetTy.getElementCount().getKnownMinValue() *
- TargetElt.getSizeInBits().getFixedValue());
+ unsigned GCD = std::gcd(OrigTy.getSizeInBits().getKnownMinValue(),
+ TargetTy.getSizeInBits().getKnownMinValue());
if (GCD == OrigElt.getSizeInBits())
return LLT::scalarOrVector(ElementCount::get(1, OrigTy.isScalable()),
OrigElt);
>From 3d7ccc1ea5ca544fcba0328ab19e8f46f9b5d863 Mon Sep 17 00:00:00 2001
From: Michael Maitland <michaeltmaitland at gmail.com>
Date: Tue, 6 Feb 2024 07:08:57 -0800
Subject: [PATCH 5/5] !fixup use assert instead of unreachable
---
llvm/lib/CodeGen/GlobalISel/Utils.cpp | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/llvm/lib/CodeGen/GlobalISel/Utils.cpp b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
index 503289ef679f00..26fd12f9e51c43 100644
--- a/llvm/lib/CodeGen/GlobalISel/Utils.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
@@ -1164,7 +1164,6 @@ LLT llvm::getGCDType(LLT OrigTy, LLT TargetTy) {
if (OrigTy.isVector() && TargetTy.isVector()) {
LLT OrigElt = OrigTy.getElementType();
- LLT TargetElt = TargetTy.getElementType();
// TODO: The docstring for this function says the intention is to use this
// function to build MERGE/UNMERGE instructions. It won't be the case that
@@ -1172,10 +1171,9 @@ LLT llvm::getGCDType(LLT OrigTy, LLT TargetTy) {
// could implement getGCDType between the two in the future if there was a
// need, but it is not worth it now as this function should not be used in
// that way.
- if ((OrigTy.isScalableVector() && TargetTy.isFixedVector()) ||
- (OrigTy.isFixedVector() && TargetTy.isScalableVector()))
- llvm_unreachable(
- "getGCDType not implemented between fixed and scalable vectors.");
+ assert(((OrigTy.isScalableVector() && !TargetTy.isFixedVector()) ||
+ (OrigTy.isFixedVector() && !TargetTy.isScalableVector())) &&
+ "getGCDType not implemented between fixed and scalable vectors.");
unsigned GCD = std::gcd(OrigTy.getSizeInBits().getKnownMinValue(),
TargetTy.getSizeInBits().getKnownMinValue());
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