Summary:
Jump tables for most targets cannot handle out of range indices by
themselves, so LLVM emits range checks to guard the jump
tables. WebAssembly, on the other hand, implements jump tables using
the br_table instruction, which takes a default branch target as an
operand, making the range checks redundant. This patch introduces a
new MachineFunction pass in the WebAssembly backend to find and
eliminate the redundant range checks.
Reviewers: aheejin, dschuff
Subscribers: mgorny, sbc100, jgravelle-google, hiraditya, sunfish, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D80863
Wasm doesn't have a direct way to lower indirectbr, so hook up the
IndirectBrExpandPass to lower indirectbr into a switch.
Fixes PR42498
Reviewers: aheejin
Differential Revision: https://reviews.llvm.org/D64161
llvm-svn: 365096