[lld][WebAssembly] Set the target-cpu in LTO config

[yamt]

I couldn't find an existing way to pass -mcpu=lime1 equivalent to LTO codegen.
This commit would privide one. With this commit, you can do so by passing
-mllvm -mcpu=lime1 to wasm-ld.

[llvmbot]

@llvm/pr-subscribers-lld-wasm

@llvm/pr-subscribers-lld

Author: YAMAMOTO Takashi (yamt)

Changes

I couldn't find an existing way to pass -mcpu=lime1 equivalent to LTO codegen. This commit would privide one.

---

Full diff: https://github.com/llvm/llvm-project/pull/140010.diff

1 Files Affected:

• (modified) lld/wasm/LTO.cpp (+1)

diff --git a/lld/wasm/LTO.cpp b/lld/wasm/LTO.cpp
index a877f067603e5..581104745b8ba 100644
--- a/lld/wasm/LTO.cpp
+++ b/lld/wasm/LTO.cpp
@@ -59,6 +59,7 @@ static lto::Config createConfig() {
   c.DisableVerify = ctx.arg.disableVerify;
   c.DiagHandler = diagnosticHandler;
   c.OptLevel = ctx.arg.ltoo;
+  c.CPU = getCPUStr();
   c.MAttrs = getMAttrs();
   c.CGOptLevel = ctx.arg.ltoCgo;
   c.DebugPassManager = ctx.arg.ltoDebugPassManager;

[sbc100]

Yup this looks like this is already present in the ELF version of createConfig .. I wonder why we didn't have it here before.

Can we write a test for this?

[sbc100]

I tried removing this line from the ELF linker and all the tests still passed.. so maybe testing is not easy?

[yamt]

i noticed this while building an application. i don't have smaller test cases right now.

[sbc100]

With this added how are you actually passing -mcpu=lime1? i.e. are you doing something like -mllvm,-mcpu=lime1? Can you mention that in the PR description?

[yamt]

With this added how are you actually passing -mcpu=lime1? i.e. are you doing something like -mllvm,-mcpu=lime1? Can you mention that in the PR description?

done.

i confirmed that toywasm wasm module built with https://github.com/yamt/toywasm/blob/master/build-wasm32-wasi.sh
doesn't get reference-types enabled if i did all of the following modifications.

• use wasi-sdk with Add an option to specify CFLAGS for wasm features and make lime1 the default WebAssembly/wasi-sdk#527
• add -mcpu-lime1 to toywasm build
• use wasm-ld with this commit

[llvm-ci]

LLVM Buildbot has detected a new failure on builder premerge-monolithic-windows running on premerge-windows-1 while building lld at step 5 "clean-build-dir".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/35/builds/10251

Here is the relevant piece of the build log for the reference

Step 5 (clean-build-dir) failure: Delete failed. (failure)
Step 8 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'lit :: timeout-hang.py' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 13
not env -u FILECHECK_OPTS "C:\Python39\python.exe" C:\ws\buildbot\premerge-monolithic-windows\llvm-project\llvm\utils\lit\lit.py -j1 --order=lexical Inputs/timeout-hang/run-nonexistent.txt  --timeout=1 --param external=0 | "C:\Python39\python.exe" C:\ws\buildbot\premerge-monolithic-windows\build\utils\lit\tests\timeout-hang.py 1
# executed command: not env -u FILECHECK_OPTS 'C:\Python39\python.exe' 'C:\ws\buildbot\premerge-monolithic-windows\llvm-project\llvm\utils\lit\lit.py' -j1 --order=lexical Inputs/timeout-hang/run-nonexistent.txt --timeout=1 --param external=0
# .---command stderr------------
# | lit.py: C:\ws\buildbot\premerge-monolithic-windows\llvm-project\llvm\utils\lit\lit\main.py:72: note: The test suite configuration requested an individual test timeout of 0 seconds but a timeout of 1 seconds was requested on the command line. Forcing timeout to be 1 seconds.
# `-----------------------------
# executed command: 'C:\Python39\python.exe' 'C:\ws\buildbot\premerge-monolithic-windows\build\utils\lit\tests\timeout-hang.py' 1
# .---command stdout------------
# | Testing took as long or longer than timeout
# `-----------------------------
# error: command failed with exit status: 1

--

********************