[MLIR] Use Datalayout defaults when importing LLVM

LLVM defines several default datalayouts for integer and floating point types that are not being considered when importing into MLIR. This patch remedies this.

Reviewed By: ftynse

Differential Revision: https://reviews.llvm.org/D120832

Author: wsmoses

mlir/lib/Target/LLVMIR/ConvertFromLLVMIR.cpp

@@ -22,6 +22,7 @@
 #include "mlir/Target/LLVMIR/TypeFromLLVM.h"
 #include "mlir/Translation.h"
 
+#include "llvm/ADT/StringSet.h"
 #include "llvm/ADT/TypeSwitch.h"
 #include "llvm/IR/Attributes.h"
 #include "llvm/IR/Constants.h"
@@ -93,8 +94,23 @@ DataLayoutSpecInterface
 mlir::translateDataLayout(const llvm::DataLayout &dataLayout,
                           MLIRContext *context) {
   assert(context && "expected MLIR context");
-  StringRef layout = dataLayout.getStringRepresentation();
+  std::string layoutstr = dataLayout.getStringRepresentation();
+
+  // Remaining unhandled default layout defaults
+  // e (little endian if not set)
+  // p[n]:64:64:64 (non zero address spaces have 64-bit properties)
+  std::string append =
+      "p:64:64:64-S0-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f16:16:16-f64:"
+      "64:64-f128:128:128-v64:64:64-v128:128:128-a:0:64";
+  if (layoutstr.empty())
+    layoutstr = append;
+  else
+    layoutstr = layoutstr + "-" + append;
+
+  StringRef layout(layoutstr);
+
   SmallVector<DataLayoutEntryInterface> entries;
+  StringSet<> seen;
   while (!layout.empty()) {
     // Split at '-'.
     std::pair<StringRef, StringRef> split = layout.split('-');
@@ -104,6 +120,9 @@ mlir::translateDataLayout(const llvm::DataLayout &dataLayout,
     // Split at ':'.
     StringRef kind, spec;
     std::tie(kind, spec) = current.split(':');
+    if (seen.contains(kind))
+      continue;
+    seen.insert(kind);
 
     char symbol = kind.front();
     StringRef parameter = kind.substr(1);

mlir/test/Target/LLVMIR/data-layout.ll

@@ -5,6 +5,7 @@
 ; CHECK:   #dlti.dl_entry<"dlti.endianness", "little">
 ; CHECK:   #dlti.dl_entry<i64, dense<64> : vector<2xi32>>
 ; CHECK:   #dlti.dl_entry<f80, dense<128> : vector<2xi32>>
+; CHECK:   #dlti.dl_entry<i8, dense<8> : vector<2xi32>>
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 
 declare void @foo()