Update the minimum external LLVM to 8

LLVM 8 was released on March 20, 2019, over a year ago.

.github/workflows/ci.yml

@@ -36,13 +36,13 @@ jobs:
       matrix:
         name:
           - mingw-check
-          - x86_64-gnu-llvm-7
+          - x86_64-gnu-llvm-8
           - x86_64-gnu-tools
         include:
           - name: mingw-check
             os: ubuntu-latest-xl
             env: {}
-          - name: x86_64-gnu-llvm-7
+          - name: x86_64-gnu-llvm-8
             os: ubuntu-latest-xl
             env: {}
           - name: x86_64-gnu-tools
@@ -352,7 +352,7 @@ jobs:
           - x86_64-gnu-debug
           - x86_64-gnu-distcheck
           - x86_64-gnu-full-bootstrap
-          - x86_64-gnu-llvm-7
+          - x86_64-gnu-llvm-8
           - x86_64-gnu-nopt
           - x86_64-gnu-tools
           - x86_64-mingw-1
@@ -469,7 +469,7 @@ jobs:
           - name: x86_64-gnu-full-bootstrap
             os: ubuntu-latest-xl
             env: {}
-          - name: x86_64-gnu-llvm-7
+          - name: x86_64-gnu-llvm-8
             env:
               RUST_BACKTRACE: 1
             os: ubuntu-latest-xl

src/bootstrap/native.rs

@@ -289,11 +289,11 @@ fn check_llvm_version(builder: &Builder<'_>, llvm_config: &Path) {
     let version = output(cmd.arg("--version"));
     let mut parts = version.split('.').take(2).filter_map(|s| s.parse::<u32>().ok());
     if let (Some(major), Some(_minor)) = (parts.next(), parts.next()) {
-        if major >= 7 {
+        if major >= 8 {
             return;
         }
     }
-    panic!("\n\nbad LLVM version: {}, need >=7.0\n\n", version)
+    panic!("\n\nbad LLVM version: {}, need >=8.0\n\n", version)
 }
 
 fn configure_cmake(

src/ci/azure-pipelines/auto.yml

@@ -29,7 +29,7 @@ jobs:
   - template: steps/run.yml
   strategy:
     matrix:
-      x86_64-gnu-llvm-7:
+      x86_64-gnu-llvm-8:
         RUST_BACKTRACE: 1
       dist-x86_64-linux: {}
       dist-x86_64-linux-alt:

src/ci/azure-pipelines/pr.yml

@@ -29,7 +29,7 @@ jobs:
     - template: steps/run.yml
   strategy:
     matrix:
-      x86_64-gnu-llvm-7: {}
+      x86_64-gnu-llvm-8: {}
       mingw-check: {}
       x86_64-gnu-tools:
         CI_ONLY_WHEN_SUBMODULES_CHANGED: 1

src/ci/docker/x86_64-gnu-llvm-7/Dockerfile → src/ci/docker/x86_64-gnu-llvm-8/Dockerfile

@@ -12,7 +12,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   cmake \
   sudo \
   gdb \
-  llvm-7-tools \
+  llvm-8-tools \
   libedit-dev \
   libssl-dev \
   pkg-config \
@@ -26,7 +26,7 @@ RUN sh /scripts/sccache.sh
 # using llvm-link-shared due to libffi issues -- see #34486
 ENV RUST_CONFIGURE_ARGS \
       --build=x86_64-unknown-linux-gnu \
-      --llvm-root=/usr/lib/llvm-7 \
+      --llvm-root=/usr/lib/llvm-8 \
       --enable-llvm-link-shared \
       --set rust.thin-lto-import-instr-limit=10
 

src/ci/github-actions/ci.yml

@@ -259,13 +259,13 @@ jobs:
       matrix:
         name:
           - mingw-check
-          - x86_64-gnu-llvm-7
+          - x86_64-gnu-llvm-8
           - x86_64-gnu-tools
         include:
           - name: mingw-check
             <<: *job-linux-xl
 
-          - name: x86_64-gnu-llvm-7
+          - name: x86_64-gnu-llvm-8
             <<: *job-linux-xl
 
           - name: x86_64-gnu-tools
@@ -349,7 +349,7 @@ jobs:
           - x86_64-gnu-debug
           - x86_64-gnu-distcheck
           - x86_64-gnu-full-bootstrap
-          - x86_64-gnu-llvm-7
+          - x86_64-gnu-llvm-8
           - x86_64-gnu-nopt
           - x86_64-gnu-tools
           - x86_64-mingw-1
@@ -471,7 +471,7 @@ jobs:
           - name: x86_64-gnu-full-bootstrap
             <<: *job-linux-xl
 
-          - name: x86_64-gnu-llvm-7
+          - name: x86_64-gnu-llvm-8
             env:
               RUST_BACKTRACE: 1
             <<: *job-linux-xl

src/librustc_codegen_llvm/attributes.rs

@@ -82,21 +82,12 @@ fn naked(val: &'ll Value, is_naked: bool) {
 
 pub fn set_frame_pointer_elimination(cx: &CodegenCx<'ll, '_>, llfn: &'ll Value) {
     if cx.sess().must_not_eliminate_frame_pointers() {
-        if llvm_util::get_major_version() >= 8 {
-            llvm::AddFunctionAttrStringValue(
-                llfn,
-                llvm::AttributePlace::Function,
-                const_cstr!("frame-pointer"),
-                const_cstr!("all"),
-            );
-        } else {
-            llvm::AddFunctionAttrStringValue(
-                llfn,
-                llvm::AttributePlace::Function,
-                const_cstr!("no-frame-pointer-elim"),
-                const_cstr!("true"),
-            );
-        }
+        llvm::AddFunctionAttrStringValue(
+            llfn,
+            llvm::AttributePlace::Function,
+            const_cstr!("frame-pointer"),
+            const_cstr!("all"),
+        );
     }
 }
 

src/librustc_codegen_llvm/debuginfo/metadata.rs

@@ -16,7 +16,6 @@ use crate::llvm::debuginfo::{
     DIArray, DICompositeType, DIDescriptor, DIFile, DIFlags, DILexicalBlock, DIScope, DIType,
     DebugEmissionKind,
 };
-use crate::llvm_util;
 use crate::value::Value;
 
 use log::debug;
@@ -1289,22 +1288,11 @@ fn prepare_union_metadata(
 // Enums
 //=-----------------------------------------------------------------------------
 
-/// DWARF variant support is only available starting in LLVM 8.
-/// Although the earlier enum debug info output did not work properly
-/// in all situations, it is better for the time being to continue to
-/// sometimes emit the old style rather than emit something completely
-/// useless when rust is compiled against LLVM 6 or older. LLVM 7
-/// contains an early version of the DWARF variant support, and will
-/// crash when handling the new debug info format. This function
-/// decides which representation will be emitted.
+/// DWARF variant support is only available starting in LLVM 8, but
+/// on MSVC we have to use the fallback mode, because LLVM doesn't
+/// lower variant parts to PDB.
 fn use_enum_fallback(cx: &CodegenCx<'_, '_>) -> bool {
-    // On MSVC we have to use the fallback mode, because LLVM doesn't
-    // lower variant parts to PDB.
     cx.sess().target.target.options.is_like_msvc
-        // LLVM version 7 did not release with an important bug fix;
-        // but the required patch is in the LLVM 8.  Rust LLVM reports
-        // 8 as well.
-        || llvm_util::get_major_version() < 8
 }
 
 // FIXME(eddyb) maybe precompute this? Right now it's computed once

src/librustc_codegen_llvm/intrinsic.rs

@@ -2,7 +2,6 @@ use crate::abi::{Abi, FnAbi, LlvmType, PassMode};
 use crate::builder::Builder;
 use crate::context::CodegenCx;
 use crate::llvm;
-use crate::llvm_util;
 use crate::type_::Type;
 use crate::type_of::LayoutLlvmExt;
 use crate::va_arg::emit_va_arg;
@@ -11,7 +10,7 @@ use crate::value::Value;
 use rustc_ast::ast;
 use rustc_codegen_ssa::base::{compare_simd_types, to_immediate, wants_msvc_seh};
 use rustc_codegen_ssa::common::span_invalid_monomorphization_error;
-use rustc_codegen_ssa::common::{IntPredicate, TypeKind};
+use rustc_codegen_ssa::common::TypeKind;
 use rustc_codegen_ssa::glue;
 use rustc_codegen_ssa::mir::operand::{OperandRef, OperandValue};
 use rustc_codegen_ssa::mir::place::PlaceRef;
@@ -461,46 +460,14 @@ impl IntrinsicCallMethods<'tcx> for Builder<'a, 'll, 'tcx> {
                             let is_add = name == "saturating_add";
                             let lhs = args[0].immediate();
                             let rhs = args[1].immediate();
-                            if llvm_util::get_major_version() >= 8 {
-                                let llvm_name = &format!(
-                                    "llvm.{}{}.sat.i{}",
-                                    if signed { 's' } else { 'u' },
-                                    if is_add { "add" } else { "sub" },
-                                    width
-                                );
-                                let llfn = self.get_intrinsic(llvm_name);
-                                self.call(llfn, &[lhs, rhs], None)
-                            } else {
-                                let llvm_name = &format!(
-                                    "llvm.{}{}.with.overflow.i{}",
-                                    if signed { 's' } else { 'u' },
-                                    if is_add { "add" } else { "sub" },
-                                    width
-                                );
-                                let llfn = self.get_intrinsic(llvm_name);
-                                let pair = self.call(llfn, &[lhs, rhs], None);
-                                let val = self.extract_value(pair, 0);
-                                let overflow = self.extract_value(pair, 1);
-                                let llty = self.type_ix(width);
-
-                                let limit = if signed {
-                                    let limit_lo = self
-                                        .const_uint_big(llty, (i128::MIN >> (128 - width)) as u128);
-                                    let limit_hi = self
-                                        .const_uint_big(llty, (i128::MAX >> (128 - width)) as u128);
-                                    let neg = self.icmp(
-                                        IntPredicate::IntSLT,
-                                        val,
-                                        self.const_uint(llty, 0),
-                                    );
-                                    self.select(neg, limit_hi, limit_lo)
-                                } else if is_add {
-                                    self.const_uint_big(llty, u128::MAX >> (128 - width))
-                                } else {
-                                    self.const_uint(llty, 0)
-                                };
-                                self.select(overflow, limit, val)
-                            }
+                            let llvm_name = &format!(
+                                "llvm.{}{}.sat.i{}",
+                                if signed { 's' } else { 'u' },
+                                if is_add { "add" } else { "sub" },
+                                width
+                            );
+                            let llfn = self.get_intrinsic(llvm_name);
+                            self.call(llfn, &[lhs, rhs], None)
                         }
                         _ => bug!(),
                     },

src/librustc_codegen_llvm/llvm_util.rs

@@ -83,17 +83,15 @@ unsafe fn configure_llvm(sess: &Session) {
         if !sess.opts.debugging_opts.no_generate_arange_section {
             add("-generate-arange-section", false);
         }
-        if get_major_version() >= 8 {
-            match sess
-                .opts
-                .debugging_opts
-                .merge_functions
-                .unwrap_or(sess.target.target.options.merge_functions)
-            {
-                MergeFunctions::Disabled | MergeFunctions::Trampolines => {}
-                MergeFunctions::Aliases => {
-                    add("-mergefunc-use-aliases", false);
-                }
+        match sess
+            .opts
+            .debugging_opts
+            .merge_functions
+            .unwrap_or(sess.target.target.options.merge_functions)
+        {
+            MergeFunctions::Disabled | MergeFunctions::Trampolines => {}
+            MergeFunctions::Aliases => {
+                add("-mergefunc-use-aliases", false);
             }
         }
 

src/rustllvm/PassWrapper.cpp

@@ -33,10 +33,8 @@
 #include "llvm/Transforms/Instrumentation/AddressSanitizer.h"
 #include "llvm/Support/TimeProfiler.h"
 #endif
-#if LLVM_VERSION_GE(8, 0)
 #include "llvm/Transforms/Instrumentation/ThreadSanitizer.h"
 #include "llvm/Transforms/Instrumentation/MemorySanitizer.h"
-#endif
 #if LLVM_VERSION_GE(9, 0)
 #include "llvm/Transforms/Utils/CanonicalizeAliases.h"
 #endif
@@ -138,19 +136,13 @@ extern "C" LLVMPassRef LLVMRustCreateMemorySanitizerPass(int TrackOrigins, bool
 
   return wrap(createMemorySanitizerLegacyPassPass(
       MemorySanitizerOptions{TrackOrigins, Recover, CompileKernel}));
-#elif LLVM_VERSION_GE(8, 0)
-  return wrap(createMemorySanitizerLegacyPassPass(TrackOrigins, Recover));
 #else
-  return wrap(createMemorySanitizerPass(TrackOrigins, Recover));
+  return wrap(createMemorySanitizerLegacyPassPass(TrackOrigins, Recover));
 #endif
 }
 
 extern "C" LLVMPassRef LLVMRustCreateThreadSanitizerPass() {
-#if LLVM_VERSION_GE(8, 0)
   return wrap(createThreadSanitizerLegacyPassPass());
-#else
-  return wrap(createThreadSanitizerPass());
-#endif
 }
 
 extern "C" LLVMRustPassKind LLVMRustPassKind(LLVMPassRef RustPass) {
@@ -1236,15 +1228,11 @@ LLVMRustCreateThinLTOData(LLVMRustThinLTOModule *modules,
   auto deadIsPrevailing = [&](GlobalValue::GUID G) {
     return PrevailingType::Unknown;
   };
-#if LLVM_VERSION_GE(8, 0)
   // We don't have a complete picture in our use of ThinLTO, just our immediate
   // crate, so we need `ImportEnabled = false` to limit internalization.
   // Otherwise, we sometimes lose `static` values -- see #60184.
   computeDeadSymbolsWithConstProp(Ret->Index, Ret->GUIDPreservedSymbols,
                                   deadIsPrevailing, /* ImportEnabled = */ false);
-#else
-  computeDeadSymbols(Ret->Index, Ret->GUIDPreservedSymbols, deadIsPrevailing);
-#endif
   ComputeCrossModuleImport(
     Ret->Index,
     Ret->ModuleToDefinedGVSummaries,
@@ -1277,10 +1265,8 @@ LLVMRustCreateThinLTOData(LLVMRustThinLTOModule *modules,
 #if LLVM_VERSION_GE(9, 0)
   thinLTOResolvePrevailingInIndex(Ret->Index, isPrevailing, recordNewLinkage,
                                   Ret->GUIDPreservedSymbols);
-#elif LLVM_VERSION_GE(8, 0)
-  thinLTOResolvePrevailingInIndex(Ret->Index, isPrevailing, recordNewLinkage);
 #else
-  thinLTOResolveWeakForLinkerInIndex(Ret->Index, isPrevailing, recordNewLinkage);
+  thinLTOResolvePrevailingInIndex(Ret->Index, isPrevailing, recordNewLinkage);
 #endif
 
   // Here we calculate an `ExportedGUIDs` set for use in the `isExported`
@@ -1346,11 +1332,7 @@ extern "C" bool
 LLVMRustPrepareThinLTOResolveWeak(const LLVMRustThinLTOData *Data, LLVMModuleRef M) {
   Module &Mod = *unwrap(M);
   const auto &DefinedGlobals = Data->ModuleToDefinedGVSummaries.lookup(Mod.getModuleIdentifier());
-#if LLVM_VERSION_GE(8, 0)
   thinLTOResolvePrevailingInModule(Mod, DefinedGlobals);
-#else
-  thinLTOResolveWeakForLinkerModule(Mod, DefinedGlobals);
-#endif
   return true;
 }