[llvm] [GISel] Add support for scalable vectors in getLCMType (PR #80306)
Michael Maitland via llvm-commits
llvm-commits at lists.llvm.org
Thu Feb 1 08:30:37 PST 2024
https://github.com/michaelmaitland created https://github.com/llvm/llvm-project/pull/80306
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 getLCMType to handle when at least one of the types is a scalable vector. getLCMType between a fixed and scalable vector is not implemented since the docstring of the function explains that getLCMType is used to build MERGE/UNMERGE instructions and we will never build a MERGE/UNMERGE between fixed and scalable vectors.
>From 880654b0d2833d87a7ee64dfd02bcd97f6aa1471 Mon Sep 17 00:00:00 2001
From: Michael Maitland <michaeltmaitland at gmail.com>
Date: Thu, 1 Feb 2024 08:22:22 -0800
Subject: [PATCH] [GISel] Add support for scalable vectors in getLCMType
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 getLCMType to handle when at
least one of the types is a scalable vector. getLCMType between a fixed
and scalable vector is not implemented since the docstring of the
function explains that getLCMType 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 | 9 +-
llvm/lib/CodeGen/GlobalISel/Utils.cpp | 104 +++++++++++-------
.../CodeGen/GlobalISel/GISelUtilsTest.cpp | 87 +++++++++++++++
3 files changed, 159 insertions(+), 41 deletions(-)
diff --git a/llvm/include/llvm/CodeGen/GlobalISel/Utils.h b/llvm/include/llvm/CodeGen/GlobalISel/Utils.h
index bf02911e19351..c96e4217d21f0 100644
--- a/llvm/include/llvm/CodeGen/GlobalISel/Utils.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/Utils.h
@@ -343,10 +343,13 @@ Register getFunctionLiveInPhysReg(MachineFunction &MF,
const TargetRegisterClass &RC,
const DebugLoc &DL, LLT RegTy = LLT());
-/// Return the least common multiple type of \p OrigTy and \p TargetTy, by changing the
-/// number of vector elements or scalar bitwidth. The intent is a
+/// Return the least common multiple type of \p OrigTy and \p TargetTy, by
+/// changing the number of vector elements or scalar bitwidth. The intent is a
/// G_MERGE_VALUES, G_BUILD_VECTOR, or G_CONCAT_VECTORS can be constructed from
-/// \p OrigTy elements, and unmerged into \p TargetTy
+/// \p OrigTy elements, and unmerged into \p TargetTy. 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.
LLVM_READNONE
LLT getLCMType(LLT OrigTy, LLT TargetTy);
diff --git a/llvm/lib/CodeGen/GlobalISel/Utils.cpp b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
index aed826a9cbc54..055081d048e04 100644
--- a/llvm/lib/CodeGen/GlobalISel/Utils.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
@@ -1071,49 +1071,76 @@ void llvm::getSelectionDAGFallbackAnalysisUsage(AnalysisUsage &AU) {
}
LLT llvm::getLCMType(LLT OrigTy, LLT TargetTy) {
- const unsigned OrigSize = OrigTy.getSizeInBits();
- const unsigned TargetSize = TargetTy.getSizeInBits();
-
- if (OrigSize == TargetSize)
- return OrigTy;
+ if (OrigTy.getSizeInBits() == TargetTy.getSizeInBits())
+ return OrigTy;
- if (OrigTy.isVector()) {
- const LLT OrigElt = OrigTy.getElementType();
-
- if (TargetTy.isVector()) {
- const LLT TargetElt = TargetTy.getElementType();
+ if (OrigTy.isVector() && TargetTy.isVector()) {
+ LLT OrigElt = OrigTy.getElementType();
+ LLT TargetElt = TargetTy.getElementType();
- if (OrigElt.getSizeInBits() == TargetElt.getSizeInBits()) {
- int GCDElts =
- std::gcd(OrigTy.getNumElements(), TargetTy.getNumElements());
- // Prefer the original element type.
- ElementCount Mul = OrigTy.getElementCount() * TargetTy.getNumElements();
- return LLT::vector(Mul.divideCoefficientBy(GCDElts),
- OrigTy.getElementType());
- }
- } else {
- if (OrigElt.getSizeInBits() == TargetSize)
- return OrigTy;
+ // 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 getLCMType 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(
+ "getLCMType not implemented between fixed and scalable vectors.");
+
+ if (OrigElt.getSizeInBits() == TargetElt.getSizeInBits()) {
+ int GCDMinElts =
+ std::gcd(OrigTy.getElementCount().getKnownMinValue(),
+ TargetTy.getElementCount().getKnownMinValue());
+ // Prefer the original element type.
+ ElementCount Mul = OrigTy.getElementCount().multiplyCoefficientBy(
+ TargetTy.getElementCount().getKnownMinValue());
+ return LLT::vector(Mul.divideCoefficientBy(GCDMinElts),
+ OrigTy.getElementType());
}
-
- unsigned LCMSize = std::lcm(OrigSize, TargetSize);
- return LLT::fixed_vector(LCMSize / OrigElt.getSizeInBits(), OrigElt);
+ unsigned LCM = std::lcm(OrigTy.getElementCount().getKnownMinValue() *
+ OrigElt.getSizeInBits().getFixedValue(),
+ TargetTy.getElementCount().getKnownMinValue() *
+ TargetElt.getSizeInBits().getFixedValue());
+ return LLT::vector(
+ ElementCount::get(LCM / OrigElt.getSizeInBits(), OrigTy.isScalable()),
+ OrigElt);
}
- if (TargetTy.isVector()) {
- unsigned LCMSize = std::lcm(OrigSize, TargetSize);
- return LLT::fixed_vector(LCMSize / OrigSize, OrigTy);
- }
-
- unsigned LCMSize = std::lcm(OrigSize, TargetSize);
-
- // Preserve pointer types.
- if (LCMSize == OrigSize)
- return OrigTy;
- if (LCMSize == TargetSize)
- return TargetTy;
-
- return LLT::scalar(LCMSize);
+ // One type is scalar, one type is vector
+ if (OrigTy.isVector() || TargetTy.isVector()) {
+ LLT VecTy = OrigTy.isVector() ? OrigTy : TargetTy;
+ LLT ScalarTy = OrigTy.isVector() ? TargetTy : OrigTy;
+ LLT EltTy = VecTy.getElementType();
+ LLT OrigEltTy = OrigTy.isVector() ? OrigTy.getElementType() : OrigTy;
+
+ // Prefer scalar type from OrigTy.
+ if (EltTy.getSizeInBits() == ScalarTy.getSizeInBits())
+ return LLT::vector(VecTy.getElementCount(), OrigEltTy);
+
+ // Different size scalars. Create vector with the same total size.
+ // LCM will take fixed/scalable from VecTy.
+ unsigned LCM =
+ std::lcm(EltTy.getSizeInBits().getFixedValue() *
+ VecTy.getElementCount().getKnownMinValue(),
+ ScalarTy.getSizeInBits().getFixedValue());
+ // Prefer type from OrigTy
+ return LLT::vector(
+ ElementCount::get(LCM / OrigEltTy.getSizeInBits(),
+ VecTy.getElementCount().isScalable()),
+ OrigEltTy);
+ }
+
+ // At this point, both types are scalars of different size
+ unsigned LCM = std::lcm(OrigTy.getSizeInBits().getFixedValue(),
+ TargetTy.getSizeInBits().getFixedValue());
+ // Preserve pointer types.
+ if (LCM == OrigTy.getSizeInBits())
+ return OrigTy;
+ if (LCM == TargetTy.getSizeInBits())
+ return TargetTy;
+ return LLT::scalar(LCM);
}
LLT llvm::getCoverTy(LLT OrigTy, LLT TargetTy) {
@@ -1131,6 +1158,7 @@ LLT llvm::getCoverTy(LLT OrigTy, LLT TargetTy) {
OrigTy.getElementType());
}
+
LLT llvm::getGCDType(LLT OrigTy, LLT TargetTy) {
const unsigned OrigSize = OrigTy.getSizeInBits();
const unsigned TargetSize = TargetTy.getSizeInBits();
diff --git a/llvm/unittests/CodeGen/GlobalISel/GISelUtilsTest.cpp b/llvm/unittests/CodeGen/GlobalISel/GISelUtilsTest.cpp
index 8fda332d5c054..92bd0a36b82b4 100644
--- a/llvm/unittests/CodeGen/GlobalISel/GISelUtilsTest.cpp
+++ b/llvm/unittests/CodeGen/GlobalISel/GISelUtilsTest.cpp
@@ -46,6 +46,37 @@ static const LLT V6P0 = LLT::fixed_vector(6, P0);
static const LLT V2P1 = LLT::fixed_vector(2, P1);
static const LLT V4P1 = LLT::fixed_vector(4, P1);
+static const LLT NXV1S1 = LLT::scalable_vector(1, S1);
+static const LLT NXV2S1 = LLT::scalable_vector(2, S1);
+static const LLT NXV3S1 = LLT::scalable_vector(3, S1);
+static const LLT NXV4S1 = LLT::scalable_vector(4, S1);
+static const LLT NXV12S1 = LLT::scalable_vector(12, S1);
+static const LLT NXV32S1 = LLT::scalable_vector(32, S1);
+static const LLT NXV64S1 = LLT::scalable_vector(64, S1);
+static const LLT NXV128S1 = LLT::scalable_vector(128, S1);
+static const LLT NXV384S1 = LLT::scalable_vector(384, S1);
+
+static const LLT NXV1S32 = LLT::scalable_vector(1, S32);
+static const LLT NXV2S32 = LLT::scalable_vector(2, S32);
+static const LLT NXV3S32 = LLT::scalable_vector(3, S32);
+static const LLT NXV4S32 = LLT::scalable_vector(4, S32);
+static const LLT NXV8S32 = LLT::scalable_vector(8, S32);
+static const LLT NXV12S32 = LLT::scalable_vector(12, S32);
+static const LLT NXV24S32 = LLT::scalable_vector(24, S32);
+
+static const LLT NXV1S64 = LLT::scalable_vector(1, S64);
+static const LLT NXV2S64 = LLT::scalable_vector(2, S64);
+static const LLT NXV3S64 = LLT::scalable_vector(3, S64);
+static const LLT NXV4S64 = LLT::scalable_vector(4, S64);
+static const LLT NXV6S64 = LLT::scalable_vector(6, S64);
+static const LLT NXV12S64 = LLT::scalable_vector(12, S64);
+
+static const LLT NXV1P0 = LLT::scalable_vector(1, P0);
+static const LLT NXV2P0 = LLT::scalable_vector(2, P0);
+static const LLT NXV3P0 = LLT::scalable_vector(3, P0);
+static const LLT NXV4P0 = LLT::scalable_vector(4, P0);
+static const LLT NXV12P0 = LLT::scalable_vector(12, P0);
+
TEST(GISelUtilsTest, getGCDType) {
EXPECT_EQ(S1, getGCDType(S1, S1));
EXPECT_EQ(S32, getGCDType(S32, S32));
@@ -244,6 +275,62 @@ TEST(GISelUtilsTest, getLCMType) {
EXPECT_EQ(V2S64, getLCMType(V2S64, P1));
EXPECT_EQ(V4P1, getLCMType(P1, V2S64));
+
+ // Scalable, Scalable
+ EXPECT_EQ(NXV32S1, getLCMType(NXV1S1, NXV1S32));
+ EXPECT_EQ(NXV1S64, getLCMType(NXV1S64, NXV1S32));
+ EXPECT_EQ(NXV2S32, getLCMType(NXV1S32, NXV1S64));
+ EXPECT_EQ(NXV1P0, getLCMType(NXV1P0, NXV1S64));
+ EXPECT_EQ(NXV1S64, getLCMType(NXV1S64, NXV1P0));
+
+ EXPECT_EQ(NXV128S1, getLCMType(NXV4S1, NXV4S32));
+ EXPECT_EQ(NXV4S64, getLCMType(NXV4S64, NXV4S32));
+ EXPECT_EQ(NXV8S32, getLCMType(NXV4S32, NXV4S64));
+ EXPECT_EQ(NXV4P0, getLCMType(NXV4P0, NXV4S64));
+ EXPECT_EQ(NXV4S64, getLCMType(NXV4S64, NXV4P0));
+
+ EXPECT_EQ(NXV64S1, getLCMType(NXV4S1, NXV2S32));
+ EXPECT_EQ(NXV4S64, getLCMType(NXV4S64, NXV2S32));
+ EXPECT_EQ(NXV4S32, getLCMType(NXV4S32, NXV2S64));
+ EXPECT_EQ(NXV4P0, getLCMType(NXV4P0, NXV2S64));
+ EXPECT_EQ(NXV4S64, getLCMType(NXV4S64, NXV2P0));
+
+ EXPECT_EQ(NXV128S1, getLCMType(NXV2S1, NXV4S32));
+ EXPECT_EQ(NXV2S64, getLCMType(NXV2S64, NXV4S32));
+ EXPECT_EQ(NXV8S32, getLCMType(NXV2S32, NXV4S64));
+ EXPECT_EQ(NXV4P0, getLCMType(NXV2P0, NXV4S64));
+ EXPECT_EQ(NXV4S64, getLCMType(NXV2S64, NXV4P0));
+
+ EXPECT_EQ(NXV384S1, getLCMType(NXV3S1, NXV4S32));
+ EXPECT_EQ(NXV6S64, getLCMType(NXV3S64, NXV4S32));
+ EXPECT_EQ(NXV24S32, getLCMType(NXV3S32, NXV4S64));
+ EXPECT_EQ(NXV12P0, getLCMType(NXV3P0, NXV4S64));
+ EXPECT_EQ(NXV12S64, getLCMType(NXV3S64, NXV4P0));
+
+ EXPECT_EQ(NXV12S1, getLCMType(NXV3S1, NXV4S1));
+ EXPECT_EQ(NXV12S32, getLCMType(NXV3S32, NXV4S32));
+ EXPECT_EQ(NXV12S64, getLCMType(NXV3S64, NXV4S64));
+ EXPECT_EQ(NXV12P0, getLCMType(NXV3P0, NXV4P0));
+
+ // Scalable, Scalar
+
+ EXPECT_EQ(NXV1S1, getLCMType(NXV1S1, S1));
+ EXPECT_EQ(NXV32S1, getLCMType(NXV1S1, S32));
+ EXPECT_EQ(NXV1S32, getLCMType(NXV1S32, S1));
+ EXPECT_EQ(NXV1S32, getLCMType(NXV1S32, S32));
+ EXPECT_EQ(NXV2S32, getLCMType(NXV1S32, S64));
+ EXPECT_EQ(NXV2S32, getLCMType(NXV2S32, S1));
+ EXPECT_EQ(NXV2S32, getLCMType(NXV2S32, S32));
+ EXPECT_EQ(NXV2S32, getLCMType(NXV2S32, S64));
+
+ EXPECT_EQ(NXV1S1, getLCMType(S1, NXV1S1));
+ EXPECT_EQ(NXV1S32, getLCMType(S32, NXV1S1));
+ EXPECT_EQ(NXV32S1, getLCMType(S1, NXV1S32));
+ EXPECT_EQ(NXV1S32, getLCMType(S32, NXV1S32));
+ EXPECT_EQ(NXV1S64, getLCMType(S64, NXV1S32));
+ EXPECT_EQ(NXV64S1, getLCMType(S1, NXV2S32));
+ EXPECT_EQ(NXV2S32, getLCMType(S32, NXV2S32));
+ EXPECT_EQ(NXV1S64, getLCMType(S64, NXV2S32));
}
TEST_F(AArch64GISelMITest, ConstFalseTest) {
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