add spans to injected coverage counters

added regions with counter expressions and counters.

Added codegen_llvm/coverageinfo mod for upcoming coverage map

Move coverage region collection to CodegenCx finalization

Moved from `query coverageinfo` (renamed from `query coverage_data`),
as discussed in the PR at:

https://github.com/rust-lang/rust/pull/73684#issuecomment-649882503

Address merge conflict in MIR instrument_coverage test

The MIR test output format changed for int types.

moved debug messages out of block.rs

This makes the block.rs calls to add coverage mapping data to the
CodegenCx much more concise and readable.

move coverage intrinsic handling into llvm impl

I realized that having half of the coverage intrinsic handling in
`rustc_codegen_ssa` and half in `rustc_codegen_llvm` meant that any
non-llvm backend would be bound to the same decisions about how the
coverage-related MIR terminators should be handled.

To fix this, I moved the non-codegen portion of coverage intrinsic
handling into its own trait, and implemented it in `rustc_codegen_llvm`
alongside `codegen_intrinsic_call`.

I also added the (required?) stubs for the new intrinsics to
`IntrepretCx::emulate_intrinsic()`, to ensure calls to this function do
not fail if called with these new but known intrinsics.

address PR Feedback on 28 June 2020 2:48pm PDT

1 files changed, 13 insertions, 1 deletions

diff --git a/src/librustc_codegen_ssa/mir/block.rs b/src/librustc_codegen_ssa/mir/block.rs
index 480f9a50320..7514eb8e889 100644
--- a/src/librustc_codegen_ssa/mir/block.rs
+++ b/src/librustc_codegen_ssa/mir/block.rs
@@ -651,6 +651,18 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         }
 
         if intrinsic.is_some() && intrinsic != Some("drop_in_place") {
+            let intrinsic = intrinsic.unwrap();
+
+            // `is_codegen_intrinsic()` allows the backend implementation to perform compile-time
+            // operations before converting the `args` to backend values.
+            if !bx.is_codegen_intrinsic(intrinsic, &args, self.instance) {
+                // If the intrinsic call was fully addressed by the `is_codegen_intrinsic()` call
+                // (as a compile-time operation), return immediately. This avoids the need to
+                // convert the arguments, the call to `codegen_intrinsic_call()`, and the return
+                // value handling.
+                return;
+            }
+
             let dest = match ret_dest {
                 _ if fn_abi.ret.is_indirect() => llargs[0],
                 ReturnDest::Nothing => {
@@ -670,7 +682,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     // third argument must be constant. This is
                     // checked by const-qualification, which also
                     // promotes any complex rvalues to constants.
-                    if i == 2 && intrinsic.unwrap().starts_with("simd_shuffle") {
+                    if i == 2 && intrinsic.starts_with("simd_shuffle") {
                         if let mir::Operand::Constant(constant) = arg {
                             let c = self.eval_mir_constant(constant);
                             let (llval, ty) = self.simd_shuffle_indices(