Auto merge of rust-lang#107651 - Kobzol:ci-single-cgu, r=<try>

[WIP] Build `rustc` with a single CGU on x64 Linux

Follow-up attempt to rust-lang#87650. I wonder if anything changed with the addition of LTO.

I also enabled a single CGU only for the actual build of the compiler on CI, so that we can better see the perf. effects on the bootstrap benchmark.

Author: bors

.github/workflows/ci.yml

@@ -529,7 +529,6 @@ jobs:
   try:
     name: "try - ${{ matrix.name }}"
     env:
-      DIST_TRY_BUILD: 1
       CI_JOB_NAME: "${{ matrix.name }}"
       CARGO_REGISTRIES_CRATES_IO_PROTOCOL: sparse
       HEAD_SHA: "${{ github.event.pull_request.head.sha || github.sha }}"

.gitmodules

@@ -33,7 +33,7 @@
 [submodule "src/llvm-project"]
 	path = src/llvm-project
 	url = https://github.com/rust-lang/llvm-project.git
-	branch = rustc/17.0-2023-07-29
+	branch = rustc/16.0-2023-06-05
 	shallow = true
 [submodule "src/doc/embedded-book"]
 	path = src/doc/embedded-book

compiler/rustc_codegen_llvm/src/context.rs

@@ -146,17 +146,6 @@ pub unsafe fn create_module<'ll>(
             target_data_layout = target_data_layout.replace("-n32:64-", "-n64-");
         }
     }
-    if llvm_version < (17, 0, 0) {
-        if sess.target.arch.starts_with("powerpc") {
-            // LLVM 17 specifies function pointer alignment for ppc:
-            // https://reviews.llvm.org/D147016
-            target_data_layout = target_data_layout
-                .replace("-Fn32", "")
-                .replace("-Fi32", "")
-                .replace("-Fn64", "")
-                .replace("-Fi64", "");
-        }
-    }
 
     // Ensure the data-layout values hardcoded remain the defaults.
     if sess.target.is_builtin {

compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp

@@ -333,6 +333,8 @@ extern "C" void LLVMRustPrintTargetCPUs(LLVMTargetMachineRef TM,
 #if LLVM_VERSION_GE(17, 0)
   const MCSubtargetInfo *MCInfo = Target->getMCSubtargetInfo();
   const ArrayRef<SubtargetSubTypeKV> CPUTable = MCInfo->getAllProcessorDescriptions();
+#elif defined(LLVM_RUSTLLVM)
+  const ArrayRef<SubtargetSubTypeKV> CPUTable = MCInfo->getCPUTable();
 #else
   Buf << "Full target CPU help is not supported by this LLVM version.\n\n";
   SubtargetSubTypeKV TargetCPUKV = { TargetCPU, {{}}, {{}} };
@@ -1199,7 +1201,7 @@ struct LLVMRustThinLTOData {
 
   // Not 100% sure what these are, but they impact what's internalized and
   // what's inlined across modules, I believe.
-#if LLVM_VERSION_GE(18, 0)
+#if LLVM_VERSION_GE(17, 0)
   DenseMap<StringRef, FunctionImporter::ImportMapTy> ImportLists;
   DenseMap<StringRef, FunctionImporter::ExportSetTy> ExportLists;
   DenseMap<StringRef, GVSummaryMapTy> ModuleToDefinedGVSummaries;

compiler/rustc_target/src/spec/powerpc64_ibm_aix.rs

@@ -11,7 +11,7 @@ pub fn target() -> Target {
     Target {
         llvm_target: "powerpc64-ibm-aix".into(),
         pointer_width: 64,
-        data_layout: "E-m:a-Fi64-i64:64-n32:64-S128-v256:256:256-v512:512:512".into(),
+        data_layout: "E-m:a-i64:64-n32:64-S128-v256:256:256-v512:512:512".into(),
         arch: "powerpc64".into(),
         options: base,
     }

compiler/rustc_target/src/spec/powerpc64_unknown_freebsd.rs

@@ -11,7 +11,7 @@ pub fn target() -> Target {
     Target {
         llvm_target: "powerpc64-unknown-freebsd".into(),
         pointer_width: 64,
-        data_layout: "E-m:e-Fn32-i64:64-n32:64".into(),
+        data_layout: "E-m:e-i64:64-n32:64".into(),
         arch: "powerpc64".into(),
         options: TargetOptions { endian: Endian::Big, mcount: "_mcount".into(), ..base },
     }

compiler/rustc_target/src/spec/powerpc64_unknown_linux_gnu.rs

@@ -11,7 +11,7 @@ pub fn target() -> Target {
     Target {
         llvm_target: "powerpc64-unknown-linux-gnu".into(),
         pointer_width: 64,
-        data_layout: "E-m:e-Fi64-i64:64-n32:64-S128-v256:256:256-v512:512:512".into(),
+        data_layout: "E-m:e-i64:64-n32:64-S128-v256:256:256-v512:512:512".into(),
         arch: "powerpc64".into(),
         options: TargetOptions { endian: Endian::Big, mcount: "_mcount".into(), ..base },
     }

compiler/rustc_target/src/spec/powerpc64_unknown_linux_musl.rs

@@ -11,7 +11,7 @@ pub fn target() -> Target {
     Target {
         llvm_target: "powerpc64-unknown-linux-musl".into(),
         pointer_width: 64,
-        data_layout: "E-m:e-Fi64-i64:64-n32:64-S128-v256:256:256-v512:512:512".into(),
+        data_layout: "E-m:e-i64:64-n32:64-S128-v256:256:256-v512:512:512".into(),
         arch: "powerpc64".into(),
         options: TargetOptions { endian: Endian::Big, mcount: "_mcount".into(), ..base },
     }

compiler/rustc_target/src/spec/powerpc64_unknown_openbsd.rs

@@ -11,7 +11,7 @@ pub fn target() -> Target {
     Target {
         llvm_target: "powerpc64-unknown-openbsd".into(),
         pointer_width: 64,
-        data_layout: "E-m:e-Fn32-i64:64-n32:64".into(),
+        data_layout: "E-m:e-i64:64-n32:64".into(),
         arch: "powerpc64".into(),
         options: TargetOptions { endian: Endian::Big, mcount: "_mcount".into(), ..base },
     }

compiler/rustc_target/src/spec/powerpc64_wrs_vxworks.rs

@@ -11,7 +11,7 @@ pub fn target() -> Target {
     Target {
         llvm_target: "powerpc64-unknown-linux-gnu".into(),
         pointer_width: 64,
-        data_layout: "E-m:e-Fi64-i64:64-n32:64-S128-v256:256:256-v512:512:512".into(),
+        data_layout: "E-m:e-i64:64-n32:64-S128-v256:256:256-v512:512:512".into(),
         arch: "powerpc64".into(),
         options: TargetOptions { endian: Endian::Big, ..base },
     }