Set both nuw and nsw in slice size calculation

There's an old note in the code to do this, and now that LLVM-C has an API for it, we might as well.

Author: scottmcm

src/builder.rs

@@ -665,6 +665,7 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
         a + b
     }
 
+    // TODO(antoyo): should we also override the `unchecked_` versions?
     fn sub(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
         self.gcc_sub(a, b)
     }
@@ -832,31 +833,6 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
         set_rvalue_location(self, self.gcc_not(a))
     }
 
-    fn unchecked_sadd(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
-        set_rvalue_location(self, self.gcc_add(a, b))
-    }
-
-    fn unchecked_uadd(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
-        set_rvalue_location(self, self.gcc_add(a, b))
-    }
-
-    fn unchecked_ssub(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
-        set_rvalue_location(self, self.gcc_sub(a, b))
-    }
-
-    fn unchecked_usub(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
-        // TODO(antoyo): should generate poison value?
-        set_rvalue_location(self, self.gcc_sub(a, b))
-    }
-
-    fn unchecked_smul(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
-        set_rvalue_location(self, self.gcc_mul(a, b))
-    }
-
-    fn unchecked_umul(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
-        set_rvalue_location(self, self.gcc_mul(a, b))
-    }
-
     fn fadd_fast(&mut self, lhs: RValue<'gcc>, rhs: RValue<'gcc>) -> RValue<'gcc> {
         // NOTE: it seems like we cannot enable fast-mode for a single operation in GCC.
         set_rvalue_location(self, lhs + rhs)