De-LLVM the unchecked shifts [MCP#693]

This is just one part of the MCP, but it's the one that IMHO removes the most noise from the standard library code.

Seems net simpler this way, since MIR already supported heterogeneous shifts anyway, and thus it's not more work for backends than before.

1 files changed, 5 insertions, 7 deletions

diff --git a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
index 0af84ff067a..4443937bc3b 100644
--- a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
@@ -3,7 +3,7 @@ use super::place::PlaceRef;
 use super::{FunctionCx, LocalRef};
 
 use crate::base;
-use crate::common::{self, IntPredicate};
+use crate::common::IntPredicate;
 use crate::traits::*;
 use crate::MemFlags;
 
@@ -860,14 +860,12 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     bx.inbounds_gep(llty, lhs, &[rhs])
                 }
             }
-            mir::BinOp::Shl => common::build_masked_lshift(bx, lhs, rhs),
-            mir::BinOp::ShlUnchecked => {
-                let rhs = base::cast_shift_expr_rhs(bx, lhs, rhs);
+            mir::BinOp::Shl | mir::BinOp::ShlUnchecked => {
+                let rhs = base::build_shift_expr_rhs(bx, lhs, rhs, op == mir::BinOp::ShlUnchecked);
                 bx.shl(lhs, rhs)
             }
-            mir::BinOp::Shr => common::build_masked_rshift(bx, input_ty, lhs, rhs),
-            mir::BinOp::ShrUnchecked => {
-                let rhs = base::cast_shift_expr_rhs(bx, lhs, rhs);
+            mir::BinOp::Shr | mir::BinOp::ShrUnchecked => {
+                let rhs = base::build_shift_expr_rhs(bx, lhs, rhs, op == mir::BinOp::ShrUnchecked);
                 if is_signed { bx.ashr(lhs, rhs) } else { bx.lshr(lhs, rhs) }
             }
             mir::BinOp::Ne