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Rollup merge of #113723 - khei4:khei4/llvm-stats, r=oli-obk,nikic

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Resurrect: rustc_llvm: Add a -Z `print-codegen-stats` option to expose LLVM statistics.

This resurrects PR https://github.com/rust-lang/rust/pull/104000, which has sat idle for a while. And I want to see the effect of stack-move optimizations on LLVM (like https://reviews.llvm.org/D153453) :).

I have applied the changes requested by `@oli-obk` and `@nagisa`  https://github.com/rust-lang/rust/pull/104000#discussion_r1014625377 and https://github.com/rust-lang/rust/pull/104000#discussion_r1014642482 in the latest commits.

r? `@oli-obk`

-----

LLVM has a neat [statistics](https://llvm.org/docs/ProgrammersManual.html#the-statistic-class-stats-option) feature that tracks how often optimizations kick in. It's very handy for optimization work. Since we expose the LLVM pass timings, I thought it made sense to expose the LLVM statistics too.

-----
(Edit: fix broken link
(Edit2: fix segmentation fault and use malloc

If `rustc` is built with
```toml
[llvm]
assertions = true
```
Then you can see like
```
rustc +stage1 -Z print-codegen-stats -C opt-level=3  tmp.rs
===-------------------------------------------------------------------------===
                          ... Statistics Collected ...
===-------------------------------------------------------------------------===
         3 aa                           - Number of MayAlias results
       193 aa                           - Number of MustAlias results
       531 aa                           - Number of NoAlias results
...
```

And the current default build emits only
```
$ rustc +stage1 -Z print-codegen-stats -C opt-level=3  tmp.rs
===-------------------------------------------------------------------------===
                          ... Statistics Collected ...
===-------------------------------------------------------------------------===
$
```
This might be better to emit the message to tell assertion flag necessity, but now I can't find how to do that...
This commit is contained in:
Matthias Krüger 2023-07-21 06:52:27 +02:00 • committed by GitHub
commit 2734b5ada9
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10 changed files with 69 additions and 5 deletions
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24
compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
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@ -1,4 +1,5 @@
#include "LLVMWrapper.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/DiagnosticHandler.h"
#include "llvm/IR/DiagnosticInfo.h"
@ -111,9 +112,26 @@ extern "C" void LLVMRustSetNormalizedTarget(LLVMModuleRef M,
unwrap(M)->setTargetTriple(Triple::normalize(Triple));
}
extern "C" void LLVMRustPrintPassTimings() {
raw_fd_ostream OS(2, false); // stderr.
TimerGroup::printAll(OS);
extern "C" const char *LLVMRustPrintPassTimings(size_t *Len) {
std::string buf;
raw_string_ostream SS(buf);
TimerGroup::printAll(SS);
SS.flush();
*Len = buf.length();
char *CStr = (char *)malloc(*Len);
memcpy(CStr, buf.c_str(), *Len);
return CStr;
}
extern "C" const char *LLVMRustPrintStatistics(size_t *Len) {
std::string buf;
raw_string_ostream SS(buf);
llvm::PrintStatistics(SS);
SS.flush();
*Len = buf.length();
char *CStr = (char *)malloc(*Len);
memcpy(CStr, buf.c_str(), *Len);
return CStr;
}
extern "C" LLVMValueRef LLVMRustGetNamedValue(LLVMModuleRef M, const char *Name,