[llvm] [GISEL] More accounting for scalable vectors when operating on LLTs (PR #80372)

[Michael Maitland via llvm-commits]

https://github.com/michaelmaitland updated https://github.com/llvm/llvm-project/pull/80372

>From b7312571a76a24627abbe2f7e9623b4082696305 Mon Sep 17 00:00:00 2001
From: Michael Maitland <michaeltmaitland at gmail.com>
Date: Thu, 1 Feb 2024 17:38:16 -0800
Subject: [PATCH] [GISEL] More accounting for scalable vectors when operating
 on LLTs

---
 llvm/lib/CodeGen/GlobalISel/CallLowering.cpp | 13 +++++++------
 llvm/lib/CodeGen/GlobalISel/Utils.cpp        | 10 ++++++++--
 llvm/lib/CodeGen/MachineVerifier.cpp         |  7 ++++---
 3 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/llvm/lib/CodeGen/GlobalISel/CallLowering.cpp b/llvm/lib/CodeGen/GlobalISel/CallLowering.cpp
index ccd9b13d730b6..3bd1542eeb746 100644
--- a/llvm/lib/CodeGen/GlobalISel/CallLowering.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/CallLowering.cpp
@@ -412,7 +412,7 @@ static void buildCopyFromRegs(MachineIRBuilder &B, ArrayRef<Register> OrigRegs,
     // size, e.g. PartLLT == v2s64 and LLTy is v3s32, then first coerce it to
     // have the same elt type, i.e. v4s32.
     // TODO: Extend this coersion to element multiples other than just 2.
-    if (PartLLT.getSizeInBits() > LLTy.getSizeInBits() &&
+    if (TypeSize::isKnownGT(PartLLT.getSizeInBits(), LLTy.getSizeInBits()) &&
         PartLLT.getScalarSizeInBits() == LLTy.getScalarSizeInBits() * 2 &&
         Regs.size() == 1) {
       LLT NewTy = PartLLT.changeElementType(LLTy.getElementType())
@@ -529,7 +529,7 @@ static void buildCopyToRegs(MachineIRBuilder &B, ArrayRef<Register> DstRegs,
   // We could just insert a regular copy, but this is unreachable at the moment.
   assert(SrcTy != PartTy && "identical part types shouldn't reach here");
 
-  const unsigned PartSize = PartTy.getSizeInBits();
+  const TypeSize PartSize = PartTy.getSizeInBits();
 
   if (PartTy.isVector() == SrcTy.isVector() &&
       PartTy.getScalarSizeInBits() > SrcTy.getScalarSizeInBits()) {
@@ -539,7 +539,7 @@ static void buildCopyToRegs(MachineIRBuilder &B, ArrayRef<Register> DstRegs,
   }
 
   if (SrcTy.isVector() && !PartTy.isVector() &&
-      PartSize > SrcTy.getElementType().getSizeInBits()) {
+      TypeSize::isKnownGT(PartSize, SrcTy.getElementType().getSizeInBits())) {
     // Vector was scalarized, and the elements extended.
     auto UnmergeToEltTy = B.buildUnmerge(SrcTy.getElementType(), SrcReg);
     for (int i = 0, e = DstRegs.size(); i != e; ++i)
@@ -548,9 +548,10 @@ static void buildCopyToRegs(MachineIRBuilder &B, ArrayRef<Register> DstRegs,
   }
 
   if (SrcTy.isVector() && PartTy.isVector() &&
-      PartTy.getScalarSizeInBits() == SrcTy.getScalarSizeInBits() &&
-      SrcTy.getNumElements() < PartTy.getNumElements()) {
-    // A coercion like: v2f32 -> v4f32.
+      PartTy.getSizeInBits() == SrcTy.getSizeInBits() &&
+      ElementCount::isKnownLT(SrcTy.getElementCount(),
+                              PartTy.getElementCount())) {
+    // A coercion like: v2f32 -> v4f32 or nxv2f32 -> nxv4f32
     Register DstReg = DstRegs.front();
     B.buildPadVectorWithUndefElements(DstReg, SrcReg);
     return;
diff --git a/llvm/lib/CodeGen/GlobalISel/Utils.cpp b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
index aed826a9cbc54..c9fe758821f96 100644
--- a/llvm/lib/CodeGen/GlobalISel/Utils.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
@@ -1117,12 +1117,18 @@ LLT llvm::getLCMType(LLT OrigTy, LLT TargetTy) {
 }
 
 LLT llvm::getCoverTy(LLT OrigTy, LLT TargetTy) {
+
+  if ((OrigTy.isScalableVector() && TargetTy.isFixedVector()) ||
+      (OrigTy.isFixedVector() && TargetTy.isScalableVector()))
+    llvm_unreachable(
+        "getCoverTy not implemented between fixed and scalable vectors.");
+
   if (!OrigTy.isVector() || !TargetTy.isVector() || OrigTy == TargetTy ||
       (OrigTy.getScalarSizeInBits() != TargetTy.getScalarSizeInBits()))
     return getLCMType(OrigTy, TargetTy);
 
-  unsigned OrigTyNumElts = OrigTy.getNumElements();
-  unsigned TargetTyNumElts = TargetTy.getNumElements();
+  unsigned OrigTyNumElts = OrigTy.getElementCount().getKnownMinValue();
+  unsigned TargetTyNumElts = TargetTy.getElementCount().getKnownMinValue();
   if (OrigTyNumElts % TargetTyNumElts == 0)
     return OrigTy;
 
diff --git a/llvm/lib/CodeGen/MachineVerifier.cpp b/llvm/lib/CodeGen/MachineVerifier.cpp
index b182000a3d705..fe865ed6f8a0e 100644
--- a/llvm/lib/CodeGen/MachineVerifier.cpp
+++ b/llvm/lib/CodeGen/MachineVerifier.cpp
@@ -1400,7 +1400,8 @@ void MachineVerifier::verifyPreISelGenericInstruction(const MachineInstr *MI) {
     if (DstTy.isVector()) {
       // This case is the converse of G_CONCAT_VECTORS.
       if (!SrcTy.isVector() || SrcTy.getScalarType() != DstTy.getScalarType() ||
-          SrcTy.getNumElements() != NumDsts * DstTy.getNumElements())
+          SrcTy.isScalableVector() != DstTy.isScalableVector() ||
+          SrcTy.getSizeInBits() != NumDsts * DstTy.getSizeInBits())
         report("G_UNMERGE_VALUES source operand does not match vector "
                "destination operands",
                MI);
@@ -1477,8 +1478,8 @@ void MachineVerifier::verifyPreISelGenericInstruction(const MachineInstr *MI) {
     for (const MachineOperand &MO : llvm::drop_begin(MI->operands(), 2))
       if (MRI->getType(MI->getOperand(1).getReg()) != MRI->getType(MO.getReg()))
         report("G_CONCAT_VECTOR source operand types are not homogeneous", MI);
-    if (DstTy.getNumElements() !=
-        SrcTy.getNumElements() * (MI->getNumOperands() - 1))
+    if (DstTy.getElementCount() !=
+        SrcTy.getElementCount() * (MI->getNumOperands() - 1))
       report("G_CONCAT_VECTOR num dest and source elements should match", MI);
     break;
   }