Merge pull request #3384 from waywardmonkeys/excise-the-imprecise

Remove PRECISE_I32_MUL option.

src/preamble.js

@@ -1360,7 +1360,6 @@ Module['writeAsciiToMemory'] = writeAsciiToMemory;
 {{{ unSign }}}
 {{{ reSign }}}
 
-#if PRECISE_I32_MUL
 // check for imul support, and also for correctness ( https://bugs.webkit.org/show_bug.cgi?id=126345 )
 if (!Math['imul'] || Math['imul'](0xffffffff, 5) !== -5) Math['imul'] = function imul(a, b) {
   var ah  = a >>> 16;
@@ -1369,11 +1368,6 @@ if (!Math['imul'] || Math['imul'](0xffffffff, 5) !== -5) Math['imul'] = function
   var bl = b & 0xffff;
   return (al*bl + ((ah*bl + al*bh) << 16))|0;
 };
-#else
-Math['imul'] = function imul(a, b) {
-  return (a*b)|0; // fast but imprecise
-};
-#endif
 Math.imul = Math['imul'];
 
 #if PRECISE_F32

src/settings.js

@@ -100,16 +100,10 @@ var WARN_UNALIGNED = 0; // Warn at compile time about instructions that LLVM tel
                         // alignment. (this option is fastcomp-only)
 var PRECISE_I64_MATH = 1; // If enabled, i64 addition etc. is emulated - which is slow but precise. If disabled,
                           // we use the 'double trick' which is fast but incurs rounding at high values.
-                          // Note that we do not catch 32-bit multiplication by default (which must be done in
-                          // 64 bits for high values for full precision) - you must manually set PRECISE_I32_MUL
-                          // for that.
                           // If set to 2, we always include the i64 math code, which is necessary in the case
                           // that we can't know at compile time that 64-bit math is needed. For example, if you
                           // print 64-bit values with printf, but never add them, we can't know at compile time
                           // and you need to set this to 2.
-var PRECISE_I32_MUL = 1; // If enabled, i32 multiplication is done with full precision, which means it is
-                         // correct even if the value exceeds the JS double-integer limit of ~52 bits (otherwise,
-                         // rounding will occur above that range).
 var PRECISE_F32 = 0; // 0: Use JS numbers for floating-point values. These are 64-bit and do not model C++
                      //    floats exactly, which are 32-bit.
                      // 1: Model C++ floats precisely, using Math.fround, polyfilling when necessary. This

tests/core/test_i32_mul_semiprecise.in

@@ -1,26 +0,0 @@
-#include <stdio.h>
-
-typedef unsigned int uint;
-
-// from cube2, zlib licensed
-
-#define N (624)
-#define M (397)
-#define K (0x9908B0DFU)
-
-static uint state[N];
-static int next = N;
-
-void seedMT(uint seed) {
-  state[0] = seed;
-  for (uint i = 1; i < N; i++)  // if we do not do this precisely, at least we
-                                // should coerce to int immediately, not wait
-    state[i] = seed = 1812433253U * (seed ^ (seed >> 30)) + i;
-  next = 0;
-}
-
-int main() {
-  seedMT(5497);
-  for (int i = 0; i < 10; i++) printf("%d: %u\n", i, state[i]);
-  return 0;
-}

tests/core/test_i32_mul_semiprecise.out

@@ -1,10 +0,0 @@
-0: 5497
-1: 2916432318
-2: 2502517762
-3: 3151524867
-4: 2323729668
-5: 2053478917
-6: 2409490438
-7: 848473607
-8: 691103752
-9: 3915535113

tests/fuzz/creduce_tester.py

@@ -14,8 +14,7 @@ import shared, jsrun
 # configuration options will have to be hardcoded.
 CSMITH_CFLAGS = ['-I', os.path.join(os.environ['CSMITH_PATH'], 'runtime')]
 ENGINE = shared.JS_ENGINES[0]
-EMCC_ARGS = ['-O2', '-s', 'ASM_JS=1', '-s', 'PRECISE_I64_MATH=1', '-s',
-  'PRECISE_I32_MUL=1']
+EMCC_ARGS = ['-O2', '-s', 'ASM_JS=1', '-s', 'PRECISE_I64_MATH=1']
 
 filename = sys.argv[1]
 obj_filename = os.path.splitext(filename)[0]

tests/test_core.py

@@ -425,16 +425,6 @@ class T(RunnerCore): # Short name, to make it more fun to use manually on the co
 
     self.do_run_from_file(src, output)
 
-  def test_i32_mul_semiprecise(self):
-    if Settings.ASM_JS: return self.skip('asm is always fully precise')
-
-    Settings.PRECISE_I32_MUL = 0 # we want semiprecise here
-
-    test_path = path_from_root('tests', 'core', 'test_i32_mul_semiprecise')
-    src, output = (test_path + s for s in ('.in', '.out'))
-
-    self.do_run_from_file(src, output)
-
   def test_i16_emcc_intrinsic(self):
     Settings.CORRECT_SIGNS = 1 # Relevant to this test