Refactor makeHEAPView to use getHeapOffset. NFC (#21332)

The code for calculating the offsets was being duplicated here.

Also, optimize getHeapOffset to avoid any shifting when size is 1.

Author: sbc100

src/parseTools.js

@@ -297,14 +297,17 @@ function getNativeTypeSize(type) {
 
 function getHeapOffset(offset, type) {
   const sz = getNativeTypeSize(type);
-  const shifts = Math.log(sz) / Math.LN2;
+  if (sz == 1) {
+    return offset;
+  }
   if (MEMORY64 == 1) {
-    return `((${offset})/${2 ** shifts})`;
-  } else if (CAN_ADDRESS_2GB) {
+    return `((${offset})/${sz})`;
+  }
+  const shifts = Math.log(sz) / Math.LN2;
+  if (CAN_ADDRESS_2GB) {
     return `((${offset})>>>${shifts})`;
-  } else {
-    return `((${offset})>>${shifts})`;
   }
+  return `((${offset})>>${shifts})`;
 }
 
 function ensureDot(value) {
@@ -427,19 +430,24 @@ function makeSetValueImpl(ptr, pos, value, type) {
 }
 
 function makeHEAPView(which, start, end) {
-  const size = parseInt(which.replace('U', '').replace('F', '')) / 8;
-  const shift = Math.log2(size);
-  let mod = '';
-  if (size != 1) {
-    if (MEMORY64) {
-      mod = '/' + size;
-    } else if (CAN_ADDRESS_2GB) {
-      mod = '>>>' + shift;
-    } else {
-      mod = '>>' + shift;
-    }
-  }
-  return `HEAP${which}.subarray((${start})${mod}, (${end})${mod})`;
+  // The makeHEAPView, for legacy reasons, takes a heap "suffix"
+  // rather than the heap "type" that used by other APIs here.
+  const type = {
+    '8': 'i8',
+    'U8': 'u8',
+    '16': 'i16',
+    'U16': 'u16',
+    '32': 'i32',
+    'U32': 'u32',
+    '64': 'i64',
+    'U64': 'u64',
+    'F32': 'float',
+    'F64': 'double',
+  }[which];
+  const heap = getHeapForType(type);
+  start = getHeapOffset(start, type);
+  end = getHeapOffset(end, type);
+  return `${heap}.subarray((${start}), ${end})`;
 }
 
 // Given two values and an operation, returns the result of that operation.

test/code_size/embind_val_wasm.json

@@ -1,10 +1,10 @@
 {
   "a.html": 673,
   "a.html.gz": 431,
-  "a.js": 7086,
-  "a.js.gz": 3000,
+  "a.js": 7080,
+  "a.js.gz": 2999,
   "a.wasm": 11433,
   "a.wasm.gz": 5725,
-  "total": 19192,
-  "total_gz": 9156
+  "total": 19186,
+  "total_gz": 9155
 }

test/other/metadce/test_metadce_cxx_ctors1.gzsize

@@ -1 +1 @@
-9959
+9953

test/other/metadce/test_metadce_cxx_ctors1.jssize

@@ -1 +1 @@
-24516
+24510

test/other/metadce/test_metadce_cxx_ctors2.gzsize

@@ -1 +1 @@
-9944
+9939

test/other/metadce/test_metadce_cxx_ctors2.jssize

@@ -1 +1 @@
-24484
+24478

test/other/metadce/test_metadce_cxx_except.gzsize

@@ -1 +1 @@
-11032
+11034

test/other/metadce/test_metadce_cxx_except.jssize

@@ -1 +1 @@
-28406
+28382

test/other/metadce/test_metadce_cxx_except_wasm.gzsize

@@ -1 +1 @@
-9925
+9921

test/other/metadce/test_metadce_cxx_except_wasm.jssize

@@ -1 +1 @@
-24409
+24403