[llvm] da9f06c - [GISEL] G_SPLAT_VECTOR can take a splat that is larger than the vector element (#86974)

[via llvm-commits]

Author: Michael Maitland
Date: 2024-04-01T08:46:22-04:00
New Revision: da9f06c9b1179423302e3e7ccb27431ced44e548

URL: https://github.com/llvm/llvm-project/commit/da9f06c9b1179423302e3e7ccb27431ced44e548
DIFF: https://github.com/llvm/llvm-project/commit/da9f06c9b1179423302e3e7ccb27431ced44e548.diff

LOG: [GISEL] G_SPLAT_VECTOR can take a splat that is larger than the vector element (#86974)

This is what SelectionDAG does. We'd like to reuse SelectionDAG
patterns.

Added: 
    

Modified: 
    llvm/docs/GlobalISel/GenericOpcode.rst
    llvm/lib/CodeGen/MachineVerifier.cpp
    llvm/test/MachineVerifier/test_g_splat_vector.mir

Removed: 
    


################################################################################
diff  --git a/llvm/docs/GlobalISel/GenericOpcode.rst b/llvm/docs/GlobalISel/GenericOpcode.rst
index cae2c21b80d7e7..a12627c01d205b 100644
--- a/llvm/docs/GlobalISel/GenericOpcode.rst
+++ b/llvm/docs/GlobalISel/GenericOpcode.rst
@@ -690,6 +690,10 @@ G_SPLAT_VECTOR
 
 Create a vector where all elements are the scalar from the source operand.
 
+The type of the operand must be equal to or larger than the vector element
+type. If the operand is larger than the vector element type, the scalar is
+implicitly truncated to the vector element type.
+
 Vector Reduction Operations
 ---------------------------
 

diff  --git a/llvm/lib/CodeGen/MachineVerifier.cpp b/llvm/lib/CodeGen/MachineVerifier.cpp
index e4e05ce9278caf..fd7ea28426470a 100644
--- a/llvm/lib/CodeGen/MachineVerifier.cpp
+++ b/llvm/lib/CodeGen/MachineVerifier.cpp
@@ -1768,16 +1768,23 @@ void MachineVerifier::verifyPreISelGenericInstruction(const MachineInstr *MI) {
     LLT DstTy = MRI->getType(MI->getOperand(0).getReg());
     LLT SrcTy = MRI->getType(MI->getOperand(1).getReg());
 
-    if (!DstTy.isScalableVector())
+    if (!DstTy.isScalableVector()) {
       report("Destination type must be a scalable vector", MI);
+      break;
+    }
 
-    if (!SrcTy.isScalar())
+    if (!SrcTy.isScalar()) {
       report("Source type must be a scalar", MI);
+      break;
+    }
 
-    if (DstTy.getScalarType() != SrcTy)
-      report("Element type of the destination must be the same type as the "
-             "source type",
+    if (TypeSize::isKnownGT(DstTy.getElementType().getSizeInBits(),
+                            SrcTy.getSizeInBits())) {
+      report("Element type of the destination must be the same size or smaller "
+             "than the source type",
              MI);
+      break;
+    }
 
     break;
   }

diff  --git a/llvm/test/MachineVerifier/test_g_splat_vector.mir b/llvm/test/MachineVerifier/test_g_splat_vector.mir
index 0d1d8a3e6dcc64..00074349776fa7 100644
--- a/llvm/test/MachineVerifier/test_g_splat_vector.mir
+++ b/llvm/test/MachineVerifier/test_g_splat_vector.mir
@@ -22,6 +22,6 @@ body:             |
     ; CHECK: Source type must be a scalar
     %6:_(<vscale x 2 x s32>) = G_SPLAT_VECTOR %2
 
-    ; CHECK: Element type of the destination must be the same type as the source type
-    %7:_(<vscale x 2 x s64>) = G_SPLAT_VECTOR %0
+    ; CHECK: Element type of the destination must be the same size or smaller than the source type
+    %7:_(<vscale x 2 x s128>) = G_SPLAT_VECTOR %0
 ...