Auto merge of rust-lang#119440 - Nilstrieb:overflow-checks, r=<try>

[perf experiment] Enable overflow checks for not-std

r? `@ghost`

compiler/rustc_data_structures/src/sip128.rs

@@ -102,20 +102,20 @@ unsafe fn copy_nonoverlapping_small(src: *const u8, dst: *mut u8, count: usize)
             return;
         }
 
-        let mut i = 0;
-        if i + 3 < count {
+        let mut i = 0_usize;
+        if i.wrapping_add(3) < count {
             ptr::copy_nonoverlapping(src.add(i), dst.add(i), 4);
-            i += 4;
+            i = i.wrapping_add(4);
         }
 
         if i + 1 < count {
             ptr::copy_nonoverlapping(src.add(i), dst.add(i), 2);
-            i += 2
+            i = i.wrapping_add(2);
         }
 
         if i < count {
             *dst.add(i) = *src.add(i);
-            i += 1;
+            i = i.wrapping_add(1);
         }
 
         debug_assert_eq!(i, count);
@@ -211,14 +211,14 @@ impl SipHasher128 {
         debug_assert!(nbuf < BUFFER_SIZE);
         debug_assert!(nbuf + LEN < BUFFER_WITH_SPILL_SIZE);
 
-        if nbuf + LEN < BUFFER_SIZE {
+        if nbuf.wrapping_add(LEN) < BUFFER_SIZE {
             unsafe {
                 // The memcpy call is optimized away because the size is known.
                 let dst = (self.buf.as_mut_ptr() as *mut u8).add(nbuf);
                 ptr::copy_nonoverlapping(bytes.as_ptr(), dst, LEN);
             }
 
-            self.nbuf = nbuf + LEN;
+            self.nbuf = nbuf.wrapping_add(LEN);
 
             return;
         }
@@ -265,8 +265,8 @@ impl SipHasher128 {
             // This function should only be called when the write fills the buffer.
             // Therefore, when LEN == 1, the new `self.nbuf` must be zero.
             // LEN is statically known, so the branch is optimized away.
-            self.nbuf = if LEN == 1 { 0 } else { nbuf + LEN - BUFFER_SIZE };
-            self.processed += BUFFER_SIZE;
+            self.nbuf = if LEN == 1 { 0 } else { nbuf.wrapping_add(LEN).wrapping_sub(BUFFER_SIZE) };
+            self.processed = self.processed.wrapping_add(BUFFER_SIZE);
         }
     }
 
@@ -277,7 +277,7 @@ impl SipHasher128 {
         let nbuf = self.nbuf;
         debug_assert!(nbuf < BUFFER_SIZE);
 
-        if nbuf + length < BUFFER_SIZE {
+        if nbuf.wrapping_add(length) < BUFFER_SIZE {
             unsafe {
                 let dst = (self.buf.as_mut_ptr() as *mut u8).add(nbuf);
 
@@ -289,7 +289,7 @@ impl SipHasher128 {
                 }
             }
 
-            self.nbuf = nbuf + length;
+            self.nbuf = nbuf.wrapping_add(length);
 
             return;
         }
@@ -327,7 +327,7 @@ impl SipHasher128 {
             // ELEM_SIZE` to show the compiler that this loop's upper bound is > 0.
             // We know that is true, because last step ensured we have a full
             // element in the buffer.
-            let last = nbuf / ELEM_SIZE + 1;
+            let last = (nbuf / ELEM_SIZE).wrapping_add(1);
 
             for i in 0..last {
                 let elem = self.buf.get_unchecked(i).assume_init().to_le();
@@ -338,7 +338,7 @@ impl SipHasher128 {
 
             // Process the remaining element-sized chunks of input.
             let mut processed = needed_in_elem;
-            let input_left = length - processed;
+            let input_left = length.wrapping_sub(processed);
             let elems_left = input_left / ELEM_SIZE;
             let extra_bytes_left = input_left % ELEM_SIZE;
 
@@ -347,7 +347,7 @@ impl SipHasher128 {
                 self.state.v3 ^= elem;
                 Sip13Rounds::c_rounds(&mut self.state);
                 self.state.v0 ^= elem;
-                processed += ELEM_SIZE;
+                processed = processed.wrapping_add(ELEM_SIZE);
             }
 
             // Copy remaining input into start of buffer.
@@ -356,7 +356,7 @@ impl SipHasher128 {
             copy_nonoverlapping_small(src, dst, extra_bytes_left);
 
             self.nbuf = extra_bytes_left;
-            self.processed += nbuf + processed;
+            self.processed = self.processed.wrapping_add(nbuf).wrapping_add(processed);
         }
     }
 
@@ -394,7 +394,7 @@ impl SipHasher128 {
         };
 
         // Finalize the hash.
-        let length = self.processed + self.nbuf;
+        let length = self.processed.wrapping_add(self.nbuf);
         let b: u64 = ((length as u64 & 0xff) << 56) | elem;
 
         state.v3 ^= b;

compiler/rustc_middle/src/mir/interpret/mod.rs

@@ -285,7 +285,7 @@ impl AllocDecodingState {
         let counter = DECODER_SESSION_ID.fetch_add(1, Ordering::SeqCst);
 
         // Make sure this is never zero.
-        let session_id = DecodingSessionId::new((counter & 0x7FFFFFFF) + 1).unwrap();
+        let session_id = DecodingSessionId::new((counter & 0x7FFFFFFF).wrapping_add(1)).unwrap();
 
         AllocDecodingSession { state: self, session_id }
     }

compiler/rustc_query_system/src/dep_graph/serialized.rs

@@ -101,14 +101,14 @@ impl SerializedDepGraph {
         // edge list, or the end of the array if this is the last edge.
         let end = self
             .edge_list_indices
-            .get(source + 1)
+            .get(source.wrapping_add(1))
             .map(|h| h.start())
-            .unwrap_or_else(|| self.edge_list_data.len() - DEP_NODE_PAD);
+            .unwrap_or_else(|| self.edge_list_data.len().wrapping_sub(DEP_NODE_PAD));
 
         // The number of edges for this node is implicitly stored in the combination of the byte
         // width and the length.
         let bytes_per_index = header.bytes_per_index();
-        let len = (end - header.start()) / bytes_per_index;
+        let len = (end.wrapping_sub(header.start())) / bytes_per_index;
 
         // LLVM doesn't hoist EdgeHeader::mask so we do it ourselves.
         let mask = header.mask();

compiler/rustc_serialize/src/leb128.rs

@@ -24,15 +24,15 @@ macro_rules! impl_write_unsigned_leb128 {
                         *out.get_unchecked_mut(i) = value as u8;
                     }
 
-                    i += 1;
+                    i = i.wrapping_add(1);
                     break;
                 } else {
                     unsafe {
                         *out.get_unchecked_mut(i) = ((value & 0x7f) | 0x80) as u8;
                     }
 
                     value >>= 7;
-                    i += 1;
+                    i = i.wrapping_add(1);
                 }
             }
 
@@ -60,7 +60,7 @@ macro_rules! impl_read_unsigned_leb128 {
                 return byte as $int_ty;
             }
             let mut result = (byte & 0x7F) as $int_ty;
-            let mut shift = 7;
+            let mut shift = 7_usize;
             loop {
                 let byte = decoder.read_u8();
                 if (byte & 0x80) == 0 {
@@ -69,7 +69,7 @@ macro_rules! impl_read_unsigned_leb128 {
                 } else {
                     result |= ((byte & 0x7F) as $int_ty) << shift;
                 }
-                shift += 7;
+                shift = shift.wrapping_add(7);
             }
         }
     };

compiler/rustc_serialize/src/opaque.rs

@@ -65,7 +65,7 @@ impl FileEncoder {
         // Tracking position this way instead of having a `self.position` field
         // means that we only need to update `self.buffered` on a write call,
         // as opposed to updating `self.position` and `self.buffered`.
-        self.flushed + self.buffered
+        self.flushed.wrapping_add(self.buffered)
     }
 
     #[cold]
@@ -119,7 +119,7 @@ impl FileEncoder {
         }
         if let Some(dest) = self.buffer_empty().get_mut(..buf.len()) {
             dest.copy_from_slice(buf);
-            self.buffered += buf.len();
+            self.buffered = self.buffered.wrapping_add(buf.len());
         } else {
             self.write_all_cold_path(buf);
         }
@@ -158,7 +158,7 @@ impl FileEncoder {
         if written > N {
             Self::panic_invalid_write::<N>(written);
         }
-        self.buffered += written;
+        self.buffered = self.buffered.wrapping_add(written);
     }
 
     #[cold]

compiler/rustc_span/src/caching_source_map_view.rs

@@ -40,7 +40,7 @@ impl CacheEntry {
         let pos = self.file.relative_position(pos);
         let line_index = self.file.lookup_line(pos).unwrap();
         let line_bounds = self.file.line_bounds(line_index);
-        self.line_number = line_index + 1;
+        self.line_number = line_index.wrapping_add(1);
         self.line = line_bounds;
         self.touch(time_stamp);
     }
@@ -81,15 +81,15 @@ impl<'sm> CachingSourceMapView<'sm> {
         &mut self,
         pos: BytePos,
     ) -> Option<(Lrc<SourceFile>, usize, RelativeBytePos)> {
-        self.time_stamp += 1;
+        self.time_stamp = self.time_stamp.wrapping_add(1);
 
         // Check if the position is in one of the cached lines
         let cache_idx = self.cache_entry_index(pos);
         if cache_idx != -1 {
             let cache_entry = &mut self.line_cache[cache_idx as usize];
             cache_entry.touch(self.time_stamp);
 
-            let col = RelativeBytePos(pos.to_u32() - cache_entry.line.start.to_u32());
+            let col = RelativeBytePos(pos.to_u32().wrapping_sub(cache_entry.line.start.to_u32()));
             return Some((cache_entry.file.clone(), cache_entry.line_number, col));
         }
 

compiler/rustc_span/src/lib.rs

@@ -1746,7 +1746,7 @@ impl SourceFile {
 
     #[inline]
     pub fn relative_position(&self, pos: BytePos) -> RelativeBytePos {
-        RelativeBytePos::from_u32(pos.to_u32() - self.start_pos.to_u32())
+        RelativeBytePos::from_u32(pos.to_u32().wrapping_sub(self.start_pos.to_u32()))
     }
 
     #[inline]
@@ -1769,10 +1769,11 @@ impl SourceFile {
 
         let lines = self.lines();
         assert!(line_index < lines.len());
-        if line_index == (lines.len() - 1) {
+        if line_index == (lines.len().wrapping_sub(1)) {
             self.absolute_position(lines[line_index])..self.end_position()
         } else {
-            self.absolute_position(lines[line_index])..self.absolute_position(lines[line_index + 1])
+            self.absolute_position(lines[line_index])
+                ..self.absolute_position(lines[line_index.wrapping_add(1)])
         }
     }
 
@@ -2039,7 +2040,7 @@ macro_rules! impl_pos {
 
                 #[inline(always)]
                 fn add(self, rhs: $ident) -> $ident {
-                    $ident(self.0 + rhs.0)
+                    $ident(self.0.wrapping_add(rhs.0))
                 }
             }
 
@@ -2048,7 +2049,7 @@ macro_rules! impl_pos {
 
                 #[inline(always)]
                 fn sub(self, rhs: $ident) -> $ident {
-                    $ident(self.0 - rhs.0)
+                    $ident(self.0.wrapping_sub(rhs.0))
                 }
             }
         )*

compiler/rustc_span/src/span_encoding.rs

@@ -166,7 +166,7 @@ impl Span {
                 debug_assert!(len <= MAX_LEN);
                 SpanData {
                     lo: BytePos(self.lo_or_index),
-                    hi: BytePos(self.lo_or_index + len),
+                    hi: BytePos(self.lo_or_index.wrapping_add(len)),
                     ctxt: SyntaxContext::from_u32(self.ctxt_or_parent_or_marker as u32),
                     parent: None,
                 }
@@ -179,7 +179,7 @@ impl Span {
                 };
                 SpanData {
                     lo: BytePos(self.lo_or_index),
-                    hi: BytePos(self.lo_or_index + len),
+                    hi: BytePos(self.lo_or_index.wrapping_add(len)),
                     ctxt: SyntaxContext::root(),
                     parent: Some(parent),
                 }

src/bootstrap/src/core/builder.rs

@@ -1749,7 +1749,7 @@ impl<'a> Builder<'a> {
             if mode == Mode::Std {
                 self.config.rust_overflow_checks_std.to_string()
             } else {
-                self.config.rust_overflow_checks.to_string()
+                "true".into()
             },
         );