Summary:
Implement the handling of llvm::ConstantDataSequential and
llvm::ConstantAggregate for (nested) array and vector types when imporitng LLVM
IR to MLIR. In all cases, the result is a DenseElementsAttr that can be used in
either a `llvm.mlir.global` or a `llvm.mlir.constant`. Nested aggregates are
unpacked recursively until an element or a constant data is found. Nested
arrays with innermost scalar type are represented as DenseElementsAttr of
tensor type. Nested arrays with innermost vector type are represented as
DenseElementsAttr with (multidimensional) vector type.
Constant aggregates of struct type are not yet supported as the LLVM dialect
does not have a well-defined way of modeling struct-type constants.
Differential Revision: https://reviews.llvm.org/D72834
The current implementation of the LLVM-to-MLIR translation could not handle
functions used as constant values in instructions. The handling is added
trivially as `llvm.mlir.constant` can define constants of function type using
SymbolRef attributes, which works even for functions that have not been
declared yet.
Summary:
`mlir-translate -import-llvm test.ll` was going into segmentation fault if `test.ll` had `float` or `double` constants.
For example,
```
%3 = fadd double 3.030000e+01, %0
```
Now, it is handled in `Importer::getConstantAsAttr` (similar behaviour as normal integers)
Added tests for FP arithmetic
Reviewers: ftynse, mehdi_amini
Reviewed By: ftynse, mehdi_amini
Subscribers: shauheen, mehdi_amini, rriddle, jpienaar, burmako, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D71912
LLVM IR supports linkage on global objects such as global variables and
functions. Introduce the Linkage attribute into the LLVM dialect, backed by an
integer storage. Use this attribute on LLVM::GlobalOp and make it mandatory.
Implement parsing/printing of the attribute and conversion to LLVM IR.
See tensorflow/mlir#277.
PiperOrigin-RevId: 283309328
This allows GlobalOp to either take a value attribute (for simple constants) or a region that can
contain IR instructions (that must be constant-foldable) to create a ConstantExpr initializer.
Example:
// A complex initializer is constructed with an initializer region.
llvm.mlir.global constant @int_gep() : !llvm<"i32*"> {
%0 = llvm.mlir.addressof @g2 : !llvm<"i32*">
%1 = llvm.mlir.constant(2 : i32) : !llvm.i32
%2 = llvm.getelementptr %0[%1] : (!llvm<"i32*">, !llvm.i32) -> !llvm<"i32*">
llvm.return %2 : !llvm<"i32*">
}
PiperOrigin-RevId: 278717836
This adds an importer from LLVM IR or bitcode to the LLVM dialect. The importer is registered with mlir-translate.
Known issues exposed by this patch but not yet fixed:
* Globals' initializers are attributes, which makes it impossible to represent a ConstantExpr. This will be fixed in a followup.
* icmp returns i32 rather than i1.
* select and a couple of other instructions aren't implemented.
* llvm.cond_br takes its successors in a weird order.
The testing here is known to be non-exhaustive.
I'd appreciate feedback on where this functionality should live. It looks like the translator *from MLIR to LLVM* lives in Target/, but the SPIR-V deserializer lives in Dialect/ which is why I've put this here too.
PiperOrigin-RevId: 278711683
Shraiysh Vaishay