Auto merge of #87570 - nikic:llvm-13, r=nagisa

Upgrade to LLVM 13

Work in progress update to LLVM 13. Main changes:

 * InlineAsm diagnostics reported using SrcMgr diagnostic kind are now handled. Previously these used a separate diag handler.
 * Codegen tests are updated for additional attributes.
 * Some data layouts have changed.
 * Switch `#[used]` attribute from `llvm.used` to `llvm.compiler.used` to avoid SHF_GNU_RETAIN flag introduced in https://reviews.llvm.org/D97448, which appears to trigger a bug in older versions of gold.
 * Set `LLVM_INCLUDE_TESTS=OFF` to avoid Python 3.6 requirement.

Upstream issues:

 * ~~https://bugs.llvm.org/show_bug.cgi?id=51210 (InlineAsm diagnostic reporting for module asm)~~ Fixed by https://github.com/llvm/llvm-project/commit/1558bb80c01b695ce12642527cbfccf16cf54ece.
 * ~~https://bugs.llvm.org/show_bug.cgi?id=51476 (Miscompile on AArch64 due to incorrect comparison elimination)~~ Fixed by https://github.com/llvm/llvm-project/commit/81b106584f2baf33e09be2362c35c1bf2f6bfe94.
 * https://bugs.llvm.org/show_bug.cgi?id=51207 (Can't set custom section flags anymore). Problematic change reverted in our fork, https://reviews.llvm.org/D107216 posted for upstream revert.
 * https://bugs.llvm.org/show_bug.cgi?id=51211 (Regression in codegen for #83623). This is an optimization regression that we may likely have to eat for this release. The fix for #83623 was based on an incorrect premise, and this needs to be properly addressed in the MergeICmps pass.

The [compile-time impact](https://perf.rust-lang.org/compare.html?start=ef9549b6c0efb7525c9b012148689c8d070f9bc0&end=0983094463497eec22d550dad25576a894687002) is mixed, but quite positive as LLVM upgrades go.

The LLVM 13 final release is scheduled for Sep 21st. The current nightly is scheduled for stable release on Oct 21st.

r? `@ghost`

1 files changed, 3 insertions, 40 deletions

diff --git a/compiler/rustc_codegen_llvm/src/back/write.rs b/compiler/rustc_codegen_llvm/src/back/write.rs
index 5b4a187a1d5..791604a1827 100644
--- a/compiler/rustc_codegen_llvm/src/back/write.rs
+++ b/compiler/rustc_codegen_llvm/src/back/write.rs
@@ -296,39 +296,8 @@ unsafe extern "C" fn inline_asm_handler(diag: &SMDiagnostic, user: *const c_void
     }
     let (cgcx, _) = *(user as *const (&CodegenContext<LlvmCodegenBackend>, &Handler));
 
-    // Recover the post-substitution assembly code from LLVM for better
-    // diagnostics.
-    let mut have_source = false;
-    let mut buffer = String::new();
-    let mut level = llvm::DiagnosticLevel::Error;
-    let mut loc = 0;
-    let mut ranges = [0; 8];
-    let mut num_ranges = ranges.len() / 2;
-    let msg = llvm::build_string(|msg| {
-        buffer = llvm::build_string(|buffer| {
-            have_source = llvm::LLVMRustUnpackSMDiagnostic(
-                diag,
-                msg,
-                buffer,
-                &mut level,
-                &mut loc,
-                ranges.as_mut_ptr(),
-                &mut num_ranges,
-            );
-        })
-        .expect("non-UTF8 inline asm");
-    })
-    .expect("non-UTF8 SMDiagnostic");
-
-    let source = have_source.then(|| {
-        let mut spans = vec![InnerSpan::new(loc as usize, loc as usize)];
-        for i in 0..num_ranges {
-            spans.push(InnerSpan::new(ranges[i * 2] as usize, ranges[i * 2 + 1] as usize));
-        }
-        (buffer, spans)
-    });
-
-    report_inline_asm(cgcx, msg, level, cookie, source);
+    let smdiag = llvm::diagnostic::SrcMgrDiagnostic::unpack(diag);
+    report_inline_asm(cgcx, smdiag.message, smdiag.level, cookie, smdiag.source);
 }
 
 unsafe extern "C" fn diagnostic_handler(info: &DiagnosticInfo, user: *mut c_void) {
@@ -339,13 +308,7 @@ unsafe extern "C" fn diagnostic_handler(info: &DiagnosticInfo, user: *mut c_void
 
     match llvm::diagnostic::Diagnostic::unpack(info) {
         llvm::diagnostic::InlineAsm(inline) => {
-            report_inline_asm(
-                cgcx,
-                llvm::twine_to_string(inline.message),
-                inline.level,
-                inline.cookie,
-                None,
-            );
+            report_inline_asm(cgcx, inline.message, inline.level, inline.cookie, inline.source);
         }
 
         llvm::diagnostic::Optimization(opt) => {