diff options
Diffstat (limited to 'src/tools/wasm2js.cpp')
| -rw-r--r-- | src/tools/wasm2js.cpp | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/src/tools/wasm2js.cpp b/src/tools/wasm2js.cpp index 7ceb63ffc..611b00803 100644 --- a/src/tools/wasm2js.cpp +++ b/src/tools/wasm2js.cpp @@ -189,6 +189,10 @@ static void optimizeJS(Ref ast) { auto getHeapFromAccess = [](Ref node) { return node[1]->getIString(); }; + auto setHeapOnAccess = [](Ref node, IString heap) { + node[1] = ValueBuilder::makeName(heap); + }; + auto isIntegerHeap = [](IString heap) { return heap == HEAP8 || heap == HEAPU8 || heap == HEAP16 || heap == HEAPU16 || heap == HEAP32 || heap == HEAPU32; @@ -236,6 +240,21 @@ static void optimizeJS(Ref ast) { else if (isBitwise(node)) { node[2] = removeOrZero(node[2]); node[3] = removeOrZero(node[3]); + // A load into an & may allow using a simpler heap, e.g. HEAPU8[..] & 1 + // (a load of a boolean) may be HEAP8[..] & 1. The signed heaps are more + // commonly used, so it compresses better, and also they seem to have + // better performance (perhaps since HEAPU32 is at risk of not being a + // smallint). + if (node[1] == AND && isHeapAccess(node[2])) { + auto heap = getHeapFromAccess(node[2]); + if (isConstantAnd(node, 1)) { + if (heap == HEAPU8) { + setHeapOnAccess(node[2], HEAP8); + } else if (heap == HEAPU16) { + setHeapOnAccess(node[2], HEAP16); + } + } + } } // +(+x) => +x else if (isPlus(node)) { @@ -280,7 +299,6 @@ static void optimizeJS(Ref ast) { // Remove unnecessary break/continue labels, when referring to the top level. - // XXX IString invalid("__wasm2js$INVALID_LABEL__"); std::vector<Ref> breakCapturers; std::vector<Ref> continueCapturers; std::unordered_map<IString, Ref> |