[WebAssembly] Emit br_table for most switch instructions
Summary:
Always convert switches to br_tables unless there is only one case,
which is equivalent to a simple branch. This reduces code size for wasm,
and we defer possible jump table optimizations to the VM.
Addresses PR41502.
Reviewers: kripken, sunfish
Subscribers: dschuff, sbc100, jgravelle-google, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D60966
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@359038
91177308-0d34-0410-b5e6-
96231b3b80d8