cast.diff

diff --git a/src/librustc_codegen_llvm/common.rs b/src/librustc_codegen_llvm/common.rs
index 0b23aac522..61cace3920 100644
--- a/src/librustc_codegen_llvm/common.rs
+++ b/src/librustc_codegen_llvm/common.rs
@@ -290,7 +290,7 @@ impl ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {
         &self,
         cv: Scalar,
         layout: &layout::Scalar,
-        llty: &'ll Type,
+        llty: Option<&'ll Type>,
     ) -> &'ll Value {
         let bitsize = if layout.is_bool() { 1 } else { layout.value.size(self).bits() };
         match cv {
@@ -301,10 +301,16 @@ impl ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {
             Scalar::Raw { data, size } => {
                 assert_eq!(size as u64, layout.value.size(self).bytes());
                 let llval = self.const_uint_big(self.type_ix(bitsize), data);
-                if layout.value == layout::Pointer {
-                    unsafe { llvm::LLVMConstIntToPtr(llval, llty) }
-                } else {
-                    self.const_bitcast(llval, llty)
+
+                match llty {
+                    Some(llty) => {
+                        if layout.value == layout::Pointer {
+                            unsafe { llvm::LLVMConstIntToPtr(llval, llty) }
+                        } else {
+                            self.const_bitcast(llval, llty)
+                        }
+                    },
+                    None => llval,
                 }
             },
             Scalar::Ptr(ptr) => {
@@ -327,15 +333,26 @@ impl ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {
                     }
                     None => bug!("missing allocation {:?}", ptr.alloc_id),
                 };
-                let llval = unsafe { llvm::LLVMConstInBoundsGEP(
-                    self.const_bitcast(base_addr, self.type_i8p()),
-                    &self.const_usize(ptr.offset.bytes()),
-                    1,
-                ) };
-                if layout.value != layout::Pointer {
-                    unsafe { llvm::LLVMConstPtrToInt(llval, llty) }
+
+                let llval = if ptr.offset == Size::ZERO {
+                    base_addr
                 } else {
-                    self.const_bitcast(llval, llty)
+                    unsafe { llvm::LLVMConstInBoundsGEP(
+                        self.const_bitcast(base_addr, self.type_i8p()),
+                        &self.const_usize(ptr.offset.bytes()),
+                        1,
+                    ) }
+                };
+
+                match llty {
+                    Some(llty) => {
+                        if layout.value != layout::Pointer {
+                            unsafe { llvm::LLVMConstPtrToInt(llval, llty) }
+                        } else {
+                            self.const_bitcast(llval, llty)
+                        }
+                    },
+                    None => llval,
                 }
             }
         }
diff --git a/src/librustc_codegen_llvm/consts.rs b/src/librustc_codegen_llvm/consts.rs
index eb059ac453..186ff65eb9 100644
--- a/src/librustc_codegen_llvm/consts.rs
+++ b/src/librustc_codegen_llvm/consts.rs
@@ -47,7 +47,7 @@ pub fn const_alloc_to_llvm(cx: &CodegenCx<'ll, '_>, alloc: &Allocation) -> &'ll
                 value: layout::Primitive::Pointer,
                 valid_range: 0..=!0
             },
-            cx.type_i8p()
+            None,
         ));
         next_offset = offset + pointer_size;
     }
diff --git a/src/librustc_codegen_ssa/mir/constant.rs b/src/librustc_codegen_ssa/mir/constant.rs
index 78c22206ab..2b41fab67b 100644
--- a/src/librustc_codegen_ssa/mir/constant.rs
+++ b/src/librustc_codegen_ssa/mir/constant.rs
@@ -56,7 +56,7 @@ impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                         };
                         bx.scalar_to_backend(
                             prim, scalar,
-                            bx.immediate_backend_type(layout),
+                            Some(bx.immediate_backend_type(layout)),
                         )
                     } else {
                         bug!("simd shuffle field {:?}", field)
diff --git a/src/librustc_codegen_ssa/mir/operand.rs b/src/librustc_codegen_ssa/mir/operand.rs
index b4303cf5c9..96aa2b3b91 100644
--- a/src/librustc_codegen_ssa/mir/operand.rs
+++ b/src/librustc_codegen_ssa/mir/operand.rs
@@ -88,7 +88,7 @@ impl<'a, 'tcx: 'a, V: CodegenObject> OperandRef<'tcx, V> {
                 let llval = bx.scalar_to_backend(
                     x,
                     scalar,
-                    bx.immediate_backend_type(layout),
+                    Some(bx.immediate_backend_type(layout)),
                 );
                 OperandValue::Immediate(llval)
             },
@@ -104,7 +104,7 @@ impl<'a, 'tcx: 'a, V: CodegenObject> OperandRef<'tcx, V> {
                 let a_llval = bx.scalar_to_backend(
                     a,
                     a_scalar,
-                    bx.scalar_pair_element_backend_type(layout, 0, true),
+                    Some(bx.scalar_pair_element_backend_type(layout, 0, true)),
                 );
                 let b_llval = bx.const_usize((end - start) as u64);
                 OperandValue::Pair(a_llval, b_llval)
diff --git a/src/librustc_codegen_ssa/traits/consts.rs b/src/librustc_codegen_ssa/traits/consts.rs
index 32412f303c..9e2eeaca4b 100644
--- a/src/librustc_codegen_ssa/traits/consts.rs
+++ b/src/librustc_codegen_ssa/traits/consts.rs
@@ -29,7 +29,7 @@ pub trait ConstMethods<'tcx>: BackendTypes {
         &self,
         cv: Scalar,
         layout: &layout::Scalar,
-        llty: Self::Type,
+        llty: Option<Self::Type>,
     ) -> Self::Value;
     fn from_const_alloc(
         &self,