Constant fold math and string operations.

R=jkummerow@chromium.org
BUG=

Review URL: https://chromiumcodereview.appspot.com/12315005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13705 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/assembler.cc

@@ -1398,6 +1398,21 @@ ExternalReference ExternalReference::ForDeoptEntry(Address entry) {
 }
 
 
+double power_helper(double x, double y) {
+  int y_int = static_cast<int>(y);
+  if (y == y_int) {
+    return power_double_int(x, y_int);  // Returns 1 if exponent is 0.
+  }
+  if (y == 0.5) {
+    return (isinf(x)) ? V8_INFINITY : fast_sqrt(x + 0.0);  // Convert -0 to +0.
+  }
+  if (y == -0.5) {
+    return (isinf(x)) ? 0 : 1.0 / fast_sqrt(x + 0.0);  // Convert -0 to +0.
+  }
+  return power_double_double(x, y);
+}
+
+
 // Helper function to compute x^y, where y is known to be an
 // integer. Uses binary decomposition to limit the number of
 // multiplications; see the discussion in "Hacker's Delight" by Henry

src/assembler.h

@@ -968,6 +968,7 @@ inline int NumberOfBitsSet(uint32_t x) {
 bool EvalComparison(Token::Value op, double op1, double op2);
 
 // Computes pow(x, y) with the special cases in the spec for Math.pow.
+double power_helper(double x, double y);
 double power_double_int(double x, int y);
 double power_double_double(double x, double y);
 

src/flag-definitions.h

@@ -213,6 +213,7 @@ DEFINE_bool(array_bounds_checks_elimination, true,
 DEFINE_bool(array_index_dehoisting, true,
             "perform array index dehoisting")
 DEFINE_bool(dead_code_elimination, true, "use dead code elimination")
+DEFINE_bool(fold_constants, true, "use constant folding")
 DEFINE_bool(trace_dead_code_elimination, false, "trace dead code elimination")
 DEFINE_bool(unreachable_code_elimination, false,
             "eliminate unreachable code (hidden behind soft deopts)")

src/hydrogen.h

@@ -1294,9 +1294,9 @@ class HOptimizedGraphBuilder: public HGraphBuilder, public AstVisitor {
                                HValue* value,
                                NilValue nil);
 
-  HStringCharCodeAt* BuildStringCharCodeAt(HValue* context,
-                                           HValue* string,
-                                           HValue* index);
+  HInstruction* BuildStringCharCodeAt(HValue* context,
+                                      HValue* string,
+                                      HValue* index);
   HInstruction* BuildBinaryOperation(BinaryOperation* expr,
                                      HValue* left,
                                      HValue* right);

src/runtime.cc

@@ -7093,19 +7093,7 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_Math_pow) {
   }
 
   CONVERT_DOUBLE_ARG_CHECKED(y, 1);
-  int y_int = static_cast<int>(y);
-  double result;
-  if (y == y_int) {
-    result = power_double_int(x, y_int);  // Returns 1 if exponent is 0.
-  } else  if (y == 0.5) {
-    result = (isinf(x)) ? V8_INFINITY
-                        : fast_sqrt(x + 0.0);  // Convert -0 to +0.
-  } else if (y == -0.5) {
-    result = (isinf(x)) ? 0
-                        : 1.0 / fast_sqrt(x + 0.0);  // Convert -0 to +0.
-  } else {
-    result = power_double_double(x, y);
-  }
+  double result = power_helper(x, y);
   if (isnan(result)) return isolate->heap()->nan_value();
   return isolate->heap()->AllocateHeapNumber(result);
 }

test/mjsunit/constant-folding-2.js

+// Copyright 2013 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+// Flags: --nodead-code-elimination --fold-constants --allow-natives-syntax
+
+function test(f) {
+  f();
+  f();
+  %OptimizeFunctionOnNextCall(f);
+  f();
+  // Assert that there has been no deopt.
+  assertTrue(%GetOptimizationStatus(f) != 2);
+}
+
+test(function add() {
+  assertEquals(2, 1 + 1);
+  assertEquals(2.5, 1.25 + 1.25);
+  assertEquals("Infinity", String(Infinity + Infinity));
+  assertEquals("Infinity", String(Infinity + 3));
+  assertEquals("NaN", String(Infinity + (-Infinity)));
+  assertEquals("NaN", String(NaN + 2));
+  assertEquals("-Infinity", String(1 / (-0.0 + (-0.0))));
+  assertEquals("Infinity", String(1 / (-0.0 + 0.0)));
+});
+
+test(function inc() {
+  var a = 1;
+  var b = Infinity;
+  var c = -Infinity;
+  var d = NaN;
+  assertEquals(2, ++a);
+  assertEquals("Infinity", String(++b));
+  assertEquals("-Infinity", String(++c));
+  assertEquals("NaN", String(++d));
+});
+
+test(function dec() {
+  var a = 1;
+  var b = Infinity;
+  var c = -Infinity;
+  var d = NaN;
+  assertEquals(0, --a);
+  assertEquals("Infinity", String(--b));
+  assertEquals("-Infinity", String(--c));
+  assertEquals("NaN", String(--d));
+});
+
+test(function sub() {
+  assertEquals(0, 1 - 1);
+  assertEquals(0.5, 1.5 - 1);
+  assertEquals("Infinity", String(Infinity - (-Infinity)));
+  assertEquals("Infinity", String(Infinity - 3));
+  assertEquals("NaN", String(Infinity - Infinity));
+  assertEquals("NaN", String(NaN - 2));
+  assertEquals("-Infinity", String(1 / (-0.0 - 0.0)));
+  assertEquals("Infinity", String(1 / (0.0 - 0.0)));
+});
+
+test(function mul() {
+  assertEquals(1, 1 * 1);
+  assertEquals(2.25, 1.5 * 1.5);
+  assertEquals("Infinity", String(Infinity * Infinity));
+  assertEquals("-Infinity", String(Infinity * (-Infinity)));
+  assertEquals("Infinity", String(Infinity * 3));
+  assertEquals("-Infinity", String(Infinity * (-3)));
+  assertEquals("NaN", String(NaN * 3));
+  assertEquals("-Infinity", String(1 / (-0.0 * 0.0)));
+  assertEquals("Infinity", String(1 / (0.0 * 0.0)));
+});
+
+test(function div() {
+  assertEquals(1, 1 / 1);
+  assertEquals(1.5, 2.25 / 1.5);
+  assertEquals("NaN", String(Infinity / Infinity));
+  assertEquals("Infinity", String(Infinity / 3));
+  assertEquals("-Infinity", String(Infinity / (-3)));
+  assertEquals("NaN", String(NaN / 3));
+  assertEquals("-Infinity", String(1 / (-0.0)));
+  assertEquals("Infinity", String(Infinity/0.0));
+});
+
+test(function mathMin() {
+  assertEquals(1, Math.min(1, 10));
+  assertEquals(1.5, Math.min(1.5, 2.5));
+  assertEquals(0, Math.min(Infinity, 0));
+  assertEquals("Infinity", String(Math.min(Infinity, Infinity)));
+  assertEquals("-Infinity", String(Math.min(Infinity, -Infinity)));
+  assertEquals("NaN", String(Math.min(NaN, 1)));
+  assertEquals("Infinity", String(1 / Math.min(0.0, 0.0)));
+  assertEquals("-Infinity", String(1 / Math.min(-0.0, -0.0)));
+  assertEquals("-Infinity", String(1 / Math.min(0.0, -0.0)));
+});
+
+test(function mathMax() {
+  assertEquals(10, Math.max(1, 10));
+  assertEquals(2.5, Math.max(1.5, 2.5));
+  assertEquals(Infinity, Math.max(Infinity, 0));
+  assertEquals("-Infinity", String(Math.max(-Infinity, -Infinity)));
+  assertEquals("Infinity", String(Math.max(Infinity, -Infinity)));
+  assertEquals("NaN", String(Math.max(NaN, 1)));
+  assertEquals("Infinity", String(1 / Math.max(0.0, 0.0)));
+  assertEquals("-Infinity", String(1 / Math.max(-0.0, -0.0)));
+  assertEquals("Infinity", String(1 / Math.max(0.0, -0.0)));
+});
+
+test(function mathSin() {
+  assertEquals(0.0, Math.sin(0.0));
+  assertTrue(0.8 < Math.sin(1) && Math.sin(1) < 0.9);
+  assertEquals("NaN", String(Math.sin(Infinity)));
+  assertEquals("NaN", String(Math.sin(-Infinity)));
+  assertEquals("NaN", String(Math.sin(NaN)));
+});
+
+test(function mathCos() {
+  assertEquals(1.0, Math.cos(0.0));
+  assertTrue(0.5 < Math.cos(1) && Math.cos(1) < 0.6);
+  assertEquals("NaN", String(Math.cos(Infinity)));
+  assertEquals("NaN", String(Math.cos(-Infinity)));
+  assertEquals("NaN", String(Math.cos(NaN)));
+});
+
+test(function mathTan() {
+  assertEquals(0.0, Math.tan(0.0));
+  assertTrue(1.5 < Math.tan(1) && Math.tan(1) < 1.6);
+  assertEquals("NaN", String(Math.tan(Infinity)));
+  assertEquals("NaN", String(Math.tan(-Infinity)));
+  assertEquals("NaN", String(Math.tan(NaN)));
+});
+
+test(function mathExp() {
+  assertEquals(1.0, Math.exp(0.0));
+  assertTrue(2.7 < Math.exp(1) && Math.exp(1) < 2.8);
+  assertEquals("Infinity", String(Math.exp(Infinity)));
+  assertEquals("0", String(Math.exp(-Infinity)));
+  assertEquals("NaN", String(Math.exp(NaN)));
+});
+
+test(function mathLog() {
+  assertEquals(0.0, Math.log(1.0));
+  assertTrue(1 < Math.log(3) && Math.log(3) < 1.5);
+  assertEquals("Infinity", String(Math.log(Infinity)));
+  assertEquals("NaN", String(Math.log(-Infinity)));
+  assertEquals("NaN", String(Math.exp(NaN)));
+});
+
+test(function mathSqrt() {
+  assertEquals(1.0, Math.sqrt(1.0));
+  assertEquals("NaN", String(Math.sqrt(-1.0)));
+  assertEquals("Infinity", String(Math.sqrt(Infinity)));
+  assertEquals("NaN", String(Math.sqrt(-Infinity)));
+  assertEquals("NaN", String(Math.sqrt(NaN)));
+});
+
+test(function mathPowHalf() {
+  assertEquals(1.0, Math.pow(1.0, 0.5));
+  assertEquals("NaN", String(Math.sqrt(-1.0)));
+  assertEquals("Infinity", String(Math.pow(Infinity, 0.5)));
+  assertEquals("NaN", String(Math.sqrt(-Infinity, 0.5)));
+  assertEquals(0, Math.pow(Infinity, -0.5));
+  assertEquals("NaN", String(Math.sqrt(-Infinity, -0.5)));
+  assertEquals("NaN", String(Math.sqrt(NaN, 0.5)));
+});
+
+test(function mathAbs() {
+  assertEquals(1.5, Math.abs(1.5));
+  assertEquals(1.5, Math.abs(-1.5));
+  assertEquals("Infinity", String(Math.abs(Infinity)));
+  assertEquals("Infinity", String(Math.abs(-Infinity)));
+  assertEquals("NaN", String(Math.abs(NaN)));
+});
+
+test(function mathRound() {
+  assertEquals(2, Math.round(1.5));
+  assertEquals(-1, Math.round(-1.5));
+  assertEquals("Infinity", String(Math.round(Infinity)));
+  assertEquals("-Infinity", String(Math.round(-Infinity)));
+  assertEquals("Infinity", String(1 / Math.round(0.0)));
+  assertEquals("-Infinity", String(1 / Math.round(-0.0)));
+  assertEquals("NaN", String(Math.round(NaN)));
+  assertEquals(Math.pow(2, 52) + 1, Math.round(Math.pow(2, 52) + 1));
+});
+
+test(function mathFloor() {
+  assertEquals(1, Math.floor(1.5));
+  assertEquals(-2, Math.floor(-1.5));
+  assertEquals("Infinity", String(Math.floor(Infinity)));
+  assertEquals("-Infinity", String(Math.floor(-Infinity)));
+  assertEquals("Infinity", String(1 / Math.floor(0.0)));
+  assertEquals("-Infinity", String(1 / Math.floor(-0.0)));
+  assertEquals("NaN", String(Math.floor(NaN)));
+  assertEquals(Math.pow(2, 52) + 1, Math.floor(Math.pow(2, 52) + 1));
+});
+
+test(function mathPow() {
+  assertEquals(2.25, Math.pow(1.5, 2));
+  assertTrue(1.8 < Math.pow(1.5, 1.5) && Math.pow(1.5, 1.5) < 1.9);
+  assertEquals("Infinity", String(Math.pow(Infinity, 0.5)));
+  assertEquals("Infinity", String(Math.pow(-Infinity, 0.5)));
+  assertEquals(0, Math.pow(Infinity, -0.5));
+  assertEquals(0, Math.pow(Infinity, -0.5));
+  assertEquals("Infinity", String(Math.pow(Infinity, Infinity)));
+  assertEquals(0, Math.pow(Infinity, -Infinity));
+  assertEquals("NaN", String(Math.pow(Infinity, NaN)));
+  assertEquals("NaN", String(Math.pow(NaN, 2)));
+});
+
+test(function stringAdd() {
+  assertEquals("", "" + "");
+  assertEquals("folded constant", "folded " + "constant");
+  assertEquals("not folded constant1", "not folded constant" + 1);
+});
+
+test(function stringLength() {
+  assertEquals(6, "abcdef".length);
+  assertEquals(0, "".length);
+  assertEquals(-5, { length: -5 }.length);
+});
+
+test(function stringCharCodeAt() {
+  assertEquals(99, "abc".charCodeAt(2));
+  assertEquals("NaN", String("abc".charCodeAt(-1)));
+  assertEquals("NaN", String("abc".charCodeAt(4)));
+  assertEquals(98, "abc".charCodeAt(1.1));
+  assertEquals("NaN", String("abc".charCodeAt(4.1)));
+});
+
+test(function stringCharAt() {
+  assertEquals("c", "abc".charAt(2));
+  assertEquals("", "abc".charAt(-1));
+  assertEquals("", "abc".charAt(4));
+  assertEquals("b", "abc".charAt(1.1));
+  assertEquals("", "abc".charAt(4.1));
+});

tools/run-tests.py

@@ -58,8 +58,10 @@ VARIANT_FLAGS = [[],
                  ["--nocrankshaft"]]
 MODE_FLAGS = {
     "debug"   : ["--nobreak-on-abort", "--nodead-code-elimination",
-                 "--enable-slow-asserts", "--debug-code", "--verify-heap"],
-    "release" : ["--nobreak-on-abort", "--nodead-code-elimination"]}
+                 "--nofold-constants", "--enable-slow-asserts",
+                 "--debug-code", "--verify-heap"],
+    "release" : ["--nobreak-on-abort", "--nodead-code-elimination",
+                 "--nofold-constants"]}
 
 SUPPORTED_ARCHS = ["android_arm",
                    "android_ia32",

tools/test.py

@@ -685,8 +685,10 @@ SUFFIX = {
     'release' : '' }
 FLAGS = {
     'debug'   : ['--nobreak-on-abort', '--nodead-code-elimination',
-                 '--enable-slow-asserts', '--debug-code', '--verify-heap'],
-    'release' : ['--nobreak-on-abort', '--nodead-code-elimination']}
+                 '--nofold-constants', '--enable-slow-asserts',
+                 '--debug-code', '--verify-heap'],
+    'release' : ['--nobreak-on-abort', '--nodead-code-elimination',
+                 '--nofold-constants']}
 TIMEOUT_SCALEFACTOR = {
     'debug'   : 4,
     'release' : 1 }