[mlir] Fix translation of splat constants to LLVM IR

Summary:
When converting splat constants for nested sequential LLVM IR types wrapped in
MLIR, the constant conversion was erroneously assuming it was always possible
to recursively construct a constant of a sequential type given only one value.
Instead, wait until all sequential types are unpacked recursively before
constructing a scalar constant and wrapping it into the surrounding sequential
type.

Subscribers: mehdi_amini, rriddle, jpienaar, burmako, shauheen, antiagainst, nicolasvasilache, arpith-jacob, mgester, lucyrfox, aartbik, liufengdb, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D72688

1 files changed, 8 insertions, 1 deletions

diff --git a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
index e7c1862232b..c716cf33b57 100644
--- a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
@@ -49,7 +49,14 @@ llvm::Constant *ModuleTranslation::getLLVMConstant(llvm::Type *llvmType,
     auto *sequentialType = cast<llvm::SequentialType>(llvmType);
     auto elementType = sequentialType->getElementType();
     uint64_t numElements = sequentialType->getNumElements();
-    auto *child = getLLVMConstant(elementType, splatAttr.getSplatValue(), loc);
+    // Splat value is a scalar. Extract it only if the element type is not
+    // another sequence type. The recursion terminates because each step removes
+    // one outer sequential type.
+    llvm::Constant *child = getLLVMConstant(
+        elementType,
+        isa<llvm::SequentialType>(elementType) ? splatAttr
+                                               : splatAttr.getSplatValue(),
+        loc);
     if (llvmType->isVectorTy())
       return llvm::ConstantVector::getSplat(numElements, child);
     if (llvmType->isArrayTy()) {