4 Commits

Author SHA1 Message Date
Alex Bradbury
02926f9d28 [RISCV] Support lowering FrameIndex
Introduces the AddrFI "addressing mode", which is necessary simply because 
it's not possible to write a pattern that directly matches a frameindex.

Ensure callee-saved registers are accessed relative to the stackpointer. This
is necessary as callee-saved register spills are performed before the frame
pointer is set.

Move HexagonDAGToDAGISel::isOrEquivalentToAdd to SelectionDAGISel, so we can 
make use of it in the RISC-V backend.

Differential Revision: https://reviews.llvm.org/D39848

llvm-svn: 320353
2017-12-11 11:53:54 +00:00
Alex Bradbury
c88d30059b [RISCV][NFC] Clean up RISCVDAGToDAGISel::Select
As pointed out in post-commit review of r318738, `return ReplaceNode(..)` when 
both ReplaceNode and the current function return void is confusing. This patch 
moves to using a more obvious early return, and moves to just using an if to 
catch the one case we currently care about. A future patch that adds further 
custom instruction selection can introduce a switch.

llvm-svn: 318757
2017-11-21 12:00:19 +00:00
Alex Bradbury
43a1fee3ed [RISCV] Use register X0 (ZERO) for constant 0
The obvious approach of defining a pattern like the one below actually doesn't
work:
`def : Pat<(i32 0), (i32 X0)>;`

As was noted when Lanai made this change (https://reviews.llvm.org/rL288215),
attempting to handle the constant 0 in tablegen leads to assertions due to a
physical register being used where a virtual register is expected.

llvm-svn: 318738
2017-11-21 08:23:08 +00:00
Alex Bradbury
c2664c73ba [RISCV] Initial codegen support for ALU operations
This adds the minimum necessary to support codegen for simple ALU operations
on RV32. Prolog and epilog insertion, support for memory operations etc etc 
follow in future patches.

Leave guessInstructionProperties=1 until https://reviews.llvm.org/D37065 is 
reviewed and lands.

Differential Revision: https://reviews.llvm.org/D29933

llvm-svn: 316188
2017-10-19 21:37:38 +00:00