use element count in slices, not size in bytes

thestinger · thestinger · commit e1a26ad27139 · 2013-10-15T16:23:28.000-04:00
This allows the indexing bounds check or other comparisons against an
element length to avoid a multiplication by the size.
diff --git a/src/librustc/middle/trans/_match.rs b/src/librustc/middle/trans/_match.rs
@@ -1059,7 +1059,7 @@ fn extract_vec_elems(bcx: @mut Block,
         Store(bcx, slice_begin,
             GEPi(bcx, scratch.val, [0u, abi::slice_elt_base])
         );
-        Store(bcx, slice_len,
+        Store(bcx, UDiv(bcx, slice_len, vt.llunit_size),
             GEPi(bcx, scratch.val, [0u, abi::slice_elt_len])
         );
         elems[n] = scratch.val;
diff --git a/src/librustc/middle/trans/base.rs b/src/librustc/middle/trans/base.rs
@@ -54,7 +54,7 @@ use middle::trans::glue;
 use middle::trans::inline;
 use middle::trans::llrepr::LlvmRepr;
 use middle::trans::machine;
-use middle::trans::machine::{llalign_of_min, llsize_of, llsize_of_alloc};
+use middle::trans::machine::{llalign_of_min, llsize_of};
 use middle::trans::meth;
 use middle::trans::monomorphize;
 use middle::trans::tvec;
@@ -2910,7 +2910,7 @@ pub fn decl_gc_metadata(ccx: &mut CrateContext, llmod_id: &str) {
     }
 }
 
-pub fn create_module_map(ccx: &mut CrateContext) -> (ValueRef, uint, uint) {
+pub fn create_module_map(ccx: &mut CrateContext) -> (ValueRef, uint) {
     let str_slice_type = Type::struct_([Type::i8p(), ccx.int_type], false);
     let elttype = Type::struct_([str_slice_type, ccx.int_type], false);
     let maptype = Type::array(&elttype, ccx.module_data.len() as u64);
@@ -2942,7 +2942,7 @@ pub fn create_module_map(ccx: &mut CrateContext) -> (ValueRef, uint, uint) {
     unsafe {
         llvm::LLVMSetInitializer(map, C_array(elttype, elts));
     }
-    return (map, keys.len(), llsize_of_alloc(ccx, elttype));
+    return (map, keys.len())
 }
 
 
@@ -3004,19 +3004,17 @@ pub fn fill_crate_map(ccx: &mut CrateContext, map: ValueRef) {
         lib::llvm::SetLinkage(vec_elements, lib::llvm::InternalLinkage);
 
         llvm::LLVMSetInitializer(vec_elements, C_array(ccx.int_type, subcrates));
-        let (mod_map, mod_count, mod_struct_size) = create_module_map(ccx);
+        let (mod_map, mod_count) = create_module_map(ccx);
 
         llvm::LLVMSetInitializer(map, C_struct(
             [C_i32(2),
              C_struct([
                 p2i(ccx, mod_map),
-                // byte size of the module map array, an entry consists of two integers
-                C_int(ccx, ((mod_count * mod_struct_size) as int))
+                C_uint(ccx, mod_count)
              ], false),
              C_struct([
                 p2i(ccx, vec_elements),
-                // byte size of the subcrates array, an entry consists of an integer
-                C_int(ccx, (subcrates.len() * llsize_of_alloc(ccx, ccx.int_type)) as int)
+                C_uint(ccx, subcrates.len())
              ], false)
         ], false));
     }
diff --git a/src/librustc/middle/trans/consts.rs b/src/librustc/middle/trans/consts.rs
@@ -83,23 +83,18 @@ pub fn const_ptrcast(cx: &mut CrateContext, a: ValueRef, t: Type) -> ValueRef {
     }
 }
 
-pub fn const_vec(cx: @mut CrateContext, e: &ast::Expr, es: &[@ast::Expr])
-    -> (ValueRef, ValueRef, Type, bool) {
-    unsafe {
-        let vec_ty = ty::expr_ty(cx.tcx, e);
-        let unit_ty = ty::sequence_element_type(cx.tcx, vec_ty);
-        let llunitty = type_of::type_of(cx, unit_ty);
-        let unit_sz = machine::llsize_of(cx, llunitty);
-        let sz = llvm::LLVMConstMul(C_uint(cx, es.len()), unit_sz);
-        let (vs, inlineable) = vec::unzip(es.iter().map(|e| const_expr(cx, *e)));
-        // If the vector contains enums, an LLVM array won't work.
-        let v = if vs.iter().any(|vi| val_ty(*vi) != llunitty) {
-            C_struct(vs, false)
-        } else {
-            C_array(llunitty, vs)
-        };
-        return (v, sz, llunitty, inlineable.iter().fold(true, |a, &b| a && b));
-    }
+fn const_vec(cx: @mut CrateContext, e: &ast::Expr, es: &[@ast::Expr]) -> (ValueRef, Type, bool) {
+    let vec_ty = ty::expr_ty(cx.tcx, e);
+    let unit_ty = ty::sequence_element_type(cx.tcx, vec_ty);
+    let llunitty = type_of::type_of(cx, unit_ty);
+    let (vs, inlineable) = vec::unzip(es.iter().map(|e| const_expr(cx, *e)));
+    // If the vector contains enums, an LLVM array won't work.
+    let v = if vs.iter().any(|vi| val_ty(*vi) != llunitty) {
+        C_struct(vs, false)
+    } else {
+        C_array(llunitty, vs)
+    };
+    (v, llunitty, inlineable.iter().fold(true, |a, &b| a && b))
 }
 
 fn const_addr_of(cx: &mut CrateContext, cv: ValueRef) -> ValueRef {
@@ -225,9 +220,8 @@ pub fn const_expr(cx: @mut CrateContext, e: &ast::Expr) -> (ValueRef, bool) {
                             assert_eq!(abi::slice_elt_len, 1);
 
                             match ty::get(ty).sty {
-                                ty::ty_evec(_, ty::vstore_fixed(*)) => {
-                                    let size = machine::llsize_of(cx, val_ty(llconst));
-                                    llconst = C_struct([llptr, size], false);
+                                ty::ty_evec(_, ty::vstore_fixed(len)) => {
+                                    llconst = C_struct([llptr, C_uint(cx, len)], false);
                                 }
                                 _ => {}
                             }
@@ -412,14 +406,8 @@ fn const_expr_unadjusted(cx: @mut CrateContext,
                           (bv, C_uint(cx, u)),
 
                       ty::vstore_slice(_) => {
-                          let unit_ty = ty::sequence_element_type(cx.tcx, bt);
-                          let llunitty = type_of::type_of(cx, unit_ty);
-                          let unit_sz = machine::llsize_of(cx, llunitty);
-
                           let e1 = const_get_elt(cx, bv, [0]);
-                          (const_deref_ptr(cx, e1),
-                           llvm::LLVMConstUDiv(const_get_elt(cx, bv, [1]),
-                                               unit_sz))
+                          (const_deref_ptr(cx, e1), const_get_elt(cx, bv, [1]))
                       },
                       _ => cx.sess.span_bug(base.span,
                                             "index-expr base must be fixed-size or slice")
@@ -538,7 +526,7 @@ fn const_expr_unadjusted(cx: @mut CrateContext,
               }
           }
           ast::ExprVec(ref es, ast::MutImmutable) => {
-            let (v, _, _, inlineable) = const_vec(cx, e, *es);
+            let (v, _, inlineable) = const_vec(cx, e, *es);
             (v, inlineable)
           }
           ast::ExprVstore(sub, ast::ExprVstoreSlice) => {
@@ -550,7 +538,7 @@ fn const_expr_unadjusted(cx: @mut CrateContext,
                 }
               }
               ast::ExprVec(ref es, ast::MutImmutable) => {
-                let (cv, sz, llunitty, _) = const_vec(cx, e, *es);
+                let (cv, llunitty, _) = const_vec(cx, e, *es);
                 let llty = val_ty(cv);
                 let gv = do "const".with_c_str |name| {
                     llvm::LLVMAddGlobal(cx.llmod, llty.to_ref(), name)
@@ -559,7 +547,7 @@ fn const_expr_unadjusted(cx: @mut CrateContext,
                 llvm::LLVMSetGlobalConstant(gv, True);
                 SetLinkage(gv, PrivateLinkage);
                 let p = const_ptrcast(cx, gv, llunitty);
-                (C_struct([p, sz], false), false)
+                (C_struct([p, C_uint(cx, es.len())], false), false)
               }
               _ => cx.sess.span_bug(e.span, "bad const-slice expr")
             }
diff --git a/src/librustc/middle/trans/debuginfo.rs b/src/librustc/middle/trans/debuginfo.rs
@@ -1865,7 +1865,7 @@ fn vec_slice_metadata(cx: &mut CrateContext,
             offset: ComputedMemberOffset,
         },
         MemberDescription {
-            name: @"size_in_bytes",
+            name: @"length",
             llvm_type: member_llvm_types[1],
             type_metadata: type_metadata(cx, ty::mk_uint(), span),
             offset: ComputedMemberOffset,
diff --git a/src/librustc/middle/trans/expr.rs b/src/librustc/middle/trans/expr.rs
@@ -274,8 +274,12 @@ pub fn trans_to_datum(bcx: @mut Block, expr: &ast::Expr) -> DatumBlock {
                                    ty::vstore_slice(ty::re_static));
 
         let scratch = scratch_datum(bcx, slice_ty, "__adjust", false);
+
+        let vt = tvec::vec_types(bcx, datum.ty);
+        let unscaled_len = UDiv(bcx, len, vt.llunit_size);
+
         Store(bcx, base, GEPi(bcx, scratch.val, [0u, abi::slice_elt_base]));
-        Store(bcx, len, GEPi(bcx, scratch.val, [0u, abi::slice_elt_len]));
+        Store(bcx, unscaled_len, GEPi(bcx, scratch.val, [0u, abi::slice_elt_len]));
         DatumBlock {bcx: bcx, datum: scratch}
     }
 
diff --git a/src/librustc/middle/trans/tvec.rs b/src/librustc/middle/trans/tvec.rs
@@ -237,8 +237,7 @@ pub fn trans_slice_vstore(bcx: @mut Block,
         Ignore => {}
         SaveIn(lldest) => {
             Store(bcx, llfixed, GEPi(bcx, lldest, [0u, abi::slice_elt_base]));
-            let lllen = Mul(bcx, llcount, vt.llunit_size);
-            Store(bcx, lllen, GEPi(bcx, lldest, [0u, abi::slice_elt_len]));
+            Store(bcx, llcount, GEPi(bcx, lldest, [0u, abi::slice_elt_len]));
         }
     }
 
@@ -529,7 +528,8 @@ pub fn get_base_and_len(bcx: @mut Block,
         }
         ty::vstore_slice(_) => {
             let base = Load(bcx, GEPi(bcx, llval, [0u, abi::slice_elt_base]));
-            let len = Load(bcx, GEPi(bcx, llval, [0u, abi::slice_elt_len]));
+            let count = Load(bcx, GEPi(bcx, llval, [0u, abi::slice_elt_len]));
+            let len = Mul(bcx, count, vt.llunit_size);
             (base, len)
         }
         ty::vstore_uniq | ty::vstore_box => {
diff --git a/src/libstd/rand/mod.rs b/src/libstd/rand/mod.rs
@@ -52,6 +52,8 @@ fn main () {
  ```
 */
 
+use sys::size_of;
+use unstable::raw::Slice;
 use cast;
 use container::Container;
 use iter::{Iterator, range};
@@ -133,10 +135,10 @@ pub trait Rng {
     ///    println!("{:?}", v);
     /// }
     /// ```
-    fn fill_bytes(&mut self, mut dest: &mut [u8]) {
-        // this relies on the lengths being transferred correctly when
-        // transmuting between vectors like this.
-        let as_u64: &mut &mut [u64] = unsafe { cast::transmute(&mut dest) };
+    fn fill_bytes(&mut self, dest: &mut [u8]) {
+        let mut slice: Slice<u64> = unsafe { cast::transmute_copy(&dest) };
+        slice.len /= size_of::<u64>();
+        let as_u64: &mut [u64] = unsafe { cast::transmute(slice) };
         for dest in as_u64.mut_iter() {
             *dest = self.next_u64();
         }
@@ -147,7 +149,9 @@ pub trait Rng {
 
         // space for a u32
         if remaining >= 4 {
-            let as_u32: &mut &mut [u32] = unsafe { cast::transmute(&mut dest) };
+            let mut slice: Slice<u32> = unsafe { cast::transmute_copy(&dest) };
+            slice.len /= size_of::<u32>();
+            let as_u32: &mut [u32] = unsafe { cast::transmute(slice) };
             as_u32[as_u32.len() - 1] = self.next_u32();
             remaining -= 4;
         }
diff --git a/src/libstd/repr.rs b/src/libstd/repr.rs
@@ -186,12 +186,7 @@ impl<'self> ReprVisitor<'self> {
         }
     }
 
-    pub fn write_vec_range(&mut self,
-                           _mtbl: uint,
-                           ptr: *(),
-                           len: uint,
-                           inner: *TyDesc)
-                           -> bool {
+    pub fn write_vec_range(&mut self, ptr: *(), len: uint, inner: *TyDesc) -> bool {
         let mut p = ptr as *u8;
         let (sz, al) = unsafe { ((*inner).size, (*inner).align) };
         self.writer.write(['[' as u8]);
@@ -213,13 +208,8 @@ impl<'self> ReprVisitor<'self> {
         true
     }
 
-    pub fn write_unboxed_vec_repr(&mut self,
-                                  mtbl: uint,
-                                  v: &raw::Vec<()>,
-                                  inner: *TyDesc)
-                                  -> bool {
-        self.write_vec_range(mtbl, ptr::to_unsafe_ptr(&v.data),
-                             v.fill, inner)
+    pub fn write_unboxed_vec_repr(&mut self, _: uint, v: &raw::Vec<()>, inner: *TyDesc) -> bool {
+        self.write_vec_range(ptr::to_unsafe_ptr(&v.data), v.fill, inner)
     }
 
     fn write_escaped_char(&mut self, ch: char, is_str: bool) {
@@ -377,19 +367,32 @@ impl<'self> TyVisitor for ReprVisitor<'self> {
         }
     }
 
+    #[cfg(stage0)]
     fn visit_evec_slice(&mut self, mtbl: uint, inner: *TyDesc) -> bool {
         do self.get::<raw::Slice<()>> |this, s| {
             this.writer.write(['&' as u8]);
             this.write_mut_qualifier(mtbl);
-            this.write_vec_range(mtbl, s.data, s.len, inner);
+            this.write_vec_range(s.data, s.len, inner);
+        }
+    }
+
+    #[cfg(not(stage0))]
+    fn visit_evec_slice(&mut self, mtbl: uint, inner: *TyDesc) -> bool {
+        do self.get::<raw::Slice<()>> |this, s| {
+            this.writer.write(['&' as u8]);
+            this.write_mut_qualifier(mtbl);
+            let size = unsafe {
+                if (*inner).size == 0 { 1 } else { (*inner).size }
+            };
+            this.write_vec_range(s.data, s.len * size, inner);
         }
     }
 
     fn visit_evec_fixed(&mut self, n: uint, sz: uint, _align: uint,
-                        mtbl: uint, inner: *TyDesc) -> bool {
+                        _: uint, inner: *TyDesc) -> bool {
         let assumed_size = if sz == 0 { n } else { sz };
         do self.get::<()> |this, b| {
-            this.write_vec_range(mtbl, ptr::to_unsafe_ptr(b), assumed_size, inner);
+            this.write_vec_range(ptr::to_unsafe_ptr(b), assumed_size, inner);
         }
     }
 
diff --git a/src/libstd/vec.rs b/src/libstd/vec.rs
diff --git a/src/test/debug-info/vec-slices.rs b/src/test/debug-info/vec-slices.rs

Original file line number	Diff line number	Diff line change
`@@ -237,8 +237,7 @@ pub fn trans_slice_vstore(bcx: @mut Block,`
`237`	`237`	`Ignore => {}`
`238`	`238`	`SaveIn(lldest) => {`
`239`	`239`	`Store(bcx, llfixed, GEPi(bcx, lldest, [0u, abi::slice_elt_base]));`
`240`		`- let lllen = Mul(bcx, llcount, vt.llunit_size);`
`241`		`- Store(bcx, lllen, GEPi(bcx, lldest, [0u, abi::slice_elt_len]));`
	`240`	`+ Store(bcx, llcount, GEPi(bcx, lldest, [0u, abi::slice_elt_len]));`
`242`	`241`	`}`
`243`	`242`	`}`
`244`	`243`
`@@ -529,7 +528,8 @@ pub fn get_base_and_len(bcx: @mut Block,`
`529`	`528`	`}`
`530`	`529`	`ty::vstore_slice(_) => {`
`531`	`530`	`let base = Load(bcx, GEPi(bcx, llval, [0u, abi::slice_elt_base]));`
`532`		`- let len = Load(bcx, GEPi(bcx, llval, [0u, abi::slice_elt_len]));`
	`531`	`+ let count = Load(bcx, GEPi(bcx, llval, [0u, abi::slice_elt_len]));`
	`532`	`+ let len = Mul(bcx, count, vt.llunit_size);`
`533`	`533`	`(base, len)`
`534`	`534`	`}`
`535`	`535`	`ty::vstore_uniq \| ty::vstore_box => {`