RFR: 8316653: Large NMethodSizeLimit triggers assert during C1 code buffer allocation [v2]

[Daniel Lundén]

> This changeset fixes an overflow issue for the develop flag `-XX:NMethodSizeLimit`.
> 
> In summary, `java -XX:NMethodSizeLimit=2147483647` triggers an assert in `CodeCache::allocate`:
> 
> #  assert(size > 0) failed: Code cache allocation request must be > 0 but is -1932735136
> 
> Why?
> 1. The function `code_buffer_size` computes `NMethodSizeLimit + NMethodSizeLimit/10` as a signed integer (may overflow).
> 2. The `BufferBlob::create` function takes `code_buffer_size()` as argument and uses it (among other things, such as `sizeof(BufferBlob)`) to compute an unsigned size.
> 3. `BufferBlob::operator new` treats the unsigned size as signed (may overflow).
> 
> Changes:
> - Change all data types in the above chain to `uint` and leave the flag range for `NMethodSizeLimit` untouched (`range(0, max_jint)`). This ensures no overflow.
> - Add a new regression test.
> 
> ### Testing
> Platforms: windows-x64, linux-x64, linux-aarch64, macosx-x64, macosx-aarch64.
> - `tier1`
> - HotSpot parts of `tier2` and `tier3`

Daniel Lundén has updated the pull request incrementally with one additional commit since the last revision:

  Update src/hotspot/share/code/codeCache.cpp
  
  Co-authored-by: Roberto Castañeda Lozano <robcasloz at users.noreply.github.com>

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/16656/files
  - new: https://git.openjdk.org/jdk/pull/16656/files/e673ac1c..f52ef32f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16656&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16656&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/16656.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16656/head:pull/16656

PR: https://git.openjdk.org/jdk/pull/16656