Bug 1036037 - IonMonkey: Add a unit-test for folding a div to a multiply by reciprocal. r=nbp

js/src/jsapi-tests/moz.build

@@ -81,6 +81,7 @@ UNIFIED_SOURCES += [
 
 if CONFIG['ENABLE_ION']:
     UNIFIED_SOURCES += [
+        'testJitFoldsTo.cpp',
         'testJitRValueAlloc.cpp',
     ]
 

js/src/jsapi-tests/testJitFoldsTo.cpp

@@ -0,0 +1,124 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "jit/IonAnalysis.h"
+#include "jit/MIRGenerator.h"
+#include "jit/MIRGraph.h"
+#include "jit/ValueNumbering.h"
+
+#include "jsapi-tests/tests.h"
+
+using namespace js;
+using namespace js::jit;
+
+namespace {
+
+struct MinimalFunc
+{
+    LifoAlloc lifo;
+    TempAllocator alloc;
+    JitCompileOptions options;
+    CompileInfo info;
+    MIRGraph graph;
+    MIRGenerator mir;
+    uint32_t numParams;
+
+    MinimalFunc()
+      : lifo(4096),
+        alloc(&lifo),
+        options(),
+        info(0, SequentialExecution),
+        graph(&alloc),
+        mir(static_cast<CompileCompartment *>(nullptr), options, &alloc, &graph,
+            &info, static_cast<const OptimizationInfo *>(nullptr)),
+        numParams(0)
+    { }
+
+    MBasicBlock *createEntryBlock()
+    {
+        MBasicBlock *block = MBasicBlock::NewAsmJS(graph, info, nullptr, MBasicBlock::NORMAL);
+        graph.addBlock(block);
+        return block;
+    }
+
+    MParameter *createParameter()
+    {
+        MParameter *p = MParameter::New(alloc, numParams++, nullptr);
+        return p;
+    }
+
+    bool runGVN()
+    {
+        if (!SplitCriticalEdges(graph))
+            return false;
+        if (!RenumberBlocks(graph))
+            return false;
+        if (!BuildDominatorTree(graph))
+            return false;
+        ValueNumberer gvn(&mir, graph);
+        if (!gvn.run(ValueNumberer::DontUpdateAliasAnalysis))
+            return false;
+        return true;
+    }
+};
+
+} /* anonymous namespace */
+
+BEGIN_TEST(testJitFoldsTo_DivReciprocal)
+{
+    MinimalFunc func;
+    MBasicBlock *block = func.createEntryBlock();
+
+    // return p / 4.0
+    MParameter *p = func.createParameter();
+    block->add(p);
+    MConstant *c = MConstant::New(func.alloc, DoubleValue(4.0));
+    block->add(c);
+    MDiv *div = MDiv::New(func.alloc, p, c, MIRType_Double);
+    block->add(div);
+    MReturn *ret = MReturn::New(func.alloc, div);
+    block->end(ret);
+
+    if (!func.runGVN())
+        return false;
+
+    // Test that the div got folded to p * 0.25.
+    MDefinition *op = ret->getOperand(0);
+    CHECK(op->isMul());
+    CHECK(op->getOperand(0) == p);
+    CHECK(op->getOperand(1)->isConstant());
+    CHECK(op->getOperand(1)->toConstant()->value().toNumber() == 0.25);
+    return true;
+}
+END_TEST(testJitFoldsTo_DivReciprocal)
+
+BEGIN_TEST(testJitFoldsTo_NoDivReciprocal)
+{
+    MinimalFunc func;
+    MBasicBlock *block = func.createEntryBlock();
+
+    // return p / 5.0
+    MParameter *p = func.createParameter();
+    block->add(p);
+    MConstant *c = MConstant::New(func.alloc, DoubleValue(5.0));
+    block->add(c);
+    MDiv *div = MDiv::New(func.alloc, p, c, MIRType_Double);
+    block->add(div);
+    MReturn *ret = MReturn::New(func.alloc, div);
+    block->end(ret);
+
+    if (!func.runGVN())
+        return false;
+
+    // Test that the div didn't get folded.
+    MDefinition *op = ret->getOperand(0);
+    CHECK(op->isDiv());
+    CHECK(op->getOperand(0) == p);
+    CHECK(op->getOperand(1) == c);
+    return true;
+}
+END_TEST(testJitFoldsTo_NoDivReciprocal)