Rollup merge of #62474 - nikic:update-llvm, r=alexcrichton

Prepare for LLVM 9 update

Main changes:

 * In preparation for opaque pointer types, the `byval` attribute now takes a type. As such, the argument type needs to be threaded through to the function/callsite attribute application logic.
 * On ARM the `+fp-only-sp` and `+d16` features have become `-fp64` and `-d32`. I've switched the target definitions to use the new names, but also added bidirectional emulation so either can be used on any LLVM version for backwards compatibility.
 * The datalayout can now specify function pointer alignment. In particular on ARM `Fi8` is specified, which means that function pointer alignment is independent of function alignment. I've added this to our datalayouts to match LLVM (which is something we check) and strip the fnptr alignment for older LLVM versions.
 * The fmul/fadd reductions now always respect the accumulator (including for unordered reductions), so we should pass the identity instead of undef.

Open issues:

 * https://reviews.llvm.org/D62106 causes linker errors with ld.bdf due to https://sourceware.org/bugzilla/show_bug.cgi?id=24784. To avoid this I've enabled `RelaxELFRelocations`, which results in a GOTPCRELX relocation for `__tls_get_addr` and avoids the issue. However, this is likely not acceptable because relax relocations are not supported by older linker versions. We may need an LLVM option to keep using PLT for `__tls_get_addr` despite `RtLibUseGOT`.

The corresponding llvm-project PR is https://github.com/rust-lang/llvm-project/pull/19.

r? @ghost

1 files changed, 3 insertions, 0 deletions

diff --git a/src/librustc_codegen_llvm/llvm/ffi.rs b/src/librustc_codegen_llvm/llvm/ffi.rs
index 708ba79ec3a..2b22925f449 100644
--- a/src/librustc_codegen_llvm/llvm/ffi.rs
+++ b/src/librustc_codegen_llvm/llvm/ffi.rs
@@ -715,6 +715,7 @@ extern "C" {
     // Operations on scalar constants
     pub fn LLVMConstInt(IntTy: &Type, N: c_ulonglong, SignExtend: Bool) -> &Value;
     pub fn LLVMConstIntOfArbitraryPrecision(IntTy: &Type, Wn: c_uint, Ws: *const u64) -> &Value;
+    pub fn LLVMConstReal(RealTy: &Type, N: f64) -> &Value;
     pub fn LLVMConstIntGetZExtValue(ConstantVal: &Value) -> c_ulonglong;
     pub fn LLVMRustConstInt128Get(ConstantVal: &Value, SExt: bool,
                                   high: &mut u64, low: &mut u64) -> bool;
@@ -794,6 +795,7 @@ extern "C" {
     pub fn LLVMRustAddAlignmentAttr(Fn: &Value, index: c_uint, bytes: u32);
     pub fn LLVMRustAddDereferenceableAttr(Fn: &Value, index: c_uint, bytes: u64);
     pub fn LLVMRustAddDereferenceableOrNullAttr(Fn: &Value, index: c_uint, bytes: u64);
+    pub fn LLVMRustAddByValAttr(Fn: &Value, index: c_uint, ty: &Type);
     pub fn LLVMRustAddFunctionAttribute(Fn: &Value, index: c_uint, attr: Attribute);
     pub fn LLVMRustAddFunctionAttrStringValue(Fn: &Value,
                                               index: c_uint,
@@ -824,6 +826,7 @@ extern "C" {
     pub fn LLVMRustAddDereferenceableOrNullCallSiteAttr(Instr: &Value,
                                                         index: c_uint,
                                                         bytes: u64);
+    pub fn LLVMRustAddByValCallSiteAttr(Instr: &Value, index: c_uint, ty: &Type);
 
     // Operations on load/store instructions (only)
     pub fn LLVMSetVolatile(MemoryAccessInst: &Value, volatile: Bool);