Fix simd_bitmask

Author: antoyo

failing-ui-tests.txt

@@ -31,7 +31,6 @@ src/test/ui/sepcomp/sepcomp-fns-backwards.rs
 src/test/ui/sepcomp/sepcomp-fns.rs
 src/test/ui/sepcomp/sepcomp-statics.rs
 src/test/ui/simd/intrinsic/generic-arithmetic-pass.rs
-src/test/ui/simd/intrinsic/generic-bitmask-pass.rs
 src/test/ui/simd/intrinsic/generic-gather-pass.rs
 src/test/ui/simd/issue-17170.rs
 src/test/ui/simd/issue-39720.rs

src/intrinsic/simd.rs

@@ -351,7 +351,7 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>,
         let mut result = bx.context.new_rvalue_zero(result_type);
 
         let elem_size = elem_type.get_size() * 8;
-        let sign_shift = bx.context.new_rvalue_from_int(elem_type, elem_size as i32);
+        let sign_shift = bx.context.new_rvalue_from_int(elem_type, elem_size as i32 - 1);
         let one = bx.context.new_rvalue_one(elem_type);
 
         let mut shift = 0;