mikros/rust
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Rollup merge of #115638 - ldm0:ldm/llvm-args-fix, r=nikic

Browse Source 
`-Cllvm-args` usability improvement

fixes: #26338
fixes: #115564

Two problems were found during playing with `-Cllvm-args`

1. When `llvm.link-shared` is set to `false` in `config.toml`, output of `rustc -C llvm-args='--help-list-hidden'` doesn't contain `--emit-dwarf-unwind` and `--emulated-tls`. When it is set to `true`, `rustc -C llvm-args='--help-list-hidden'` emits `--emit-dwarf-unwind`, but `--emulated-tls` is still missing.
2. Setting `-Cllvm-args=--emit-dwarf-unwind=always` doesn't take any effect, but `-Cllvm-args=-machine-outliner-reruns=3` does work.

### 1

Adding `RegisterCodeGenFlags` to register codegen flags fixed the first problem. `rustc -C llvm-args='--help-list-hidden'` emits full codegen flags including `--emit-dwarf-unwind` and `--emulated-tls`.

### 2

Constructing `TargetOptions` from `InitTargetOptionsFromCodeGenFlags` in `LLVMRustCreateTargetMachine` fixed the second problem. The `LLVMRustSetLLVMOptions` calls `ParseCommandLineOptions` which parses given `llvm-args`. For options like `machine-outliner-reruns`, it just works, since the codegen logic directly consumes the parsing result:

[machine-outliner-reruns register](0537f6354c/llvm/lib/CodeGen/MachineOutliner.cpp (L114))
[machine-outliner-reruns consumption](0537f6354c/llvm/lib/CodeGen/MachineOutliner.cpp (L1138))

But for flags defined in `TargetOptions` and `MCTargetOptions` to take effect, constructing them with `InitTargetOptionsFromCodeGenFlags` is essential, or the parsing result is just not consumed. Similar patterns can be observed in [lli](0537f6354c/llvm/tools/llc/llc.cpp (L494)), [llc](0537f6354c/llvm/tools/lli/lli.cpp (L517)), etc.
This commit is contained in:
Guillaume Gomez 2023-09-08 14:10:52 +02:00 committed by GitHub
commit 575c3633f8
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 4 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
View File

@ -9,6 +9,7 @@
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/CodeGen/CommandFlags.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/IR/AutoUpgrade.h"
#include "llvm/IR/AssemblyAnnotationWriter.h"
@ -50,6 +51,8 @@
using namespace llvm;
static codegen::RegisterCodeGenFlags CGF;
typedef struct LLVMOpaquePass *LLVMPassRef;
typedef struct LLVMOpaqueTargetMachine *LLVMTargetMachineRef;
@ -422,7 +425,7 @@ extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine(
return nullptr;
}
TargetOptions Options;
TargetOptions Options = codegen::InitTargetOptionsFromCodeGenFlags(Trip);
Options.FloatABIType = FloatABI::Default;
if (UseSoftFloat) {