[WASM] Make F32x4 Tests pass on ARM hardware.

test/cctest/wasm/test-run-wasm-simd.cc

Index: test/cctest/wasm/test-run-wasm-simd.cc
diff --git a/test/cctest/wasm/test-run-wasm-simd.cc b/test/cctest/wasm/test-run-wasm-simd.cc
index 58e094ac6fc6fda28f00067891cc4009a198a0d1..0ba3ba365289fa87fa927beaba8d432f951a311f 100644
--- a/test/cctest/wasm/test-run-wasm-simd.cc
+++ b/test/cctest/wasm/test-run-wasm-simd.cc
@@ -374,21 +374,20 @@ T RecipSqrtRefine(T a, T b) {
 #define WASM_SIMD_I32x4_FROM_F32x4(x) x, WASM_SIMD_OP(kExprI32x4SConvertF32x4)
 #define WASM_SIMD_U32x4_FROM_F32x4(x) x, WASM_SIMD_OP(kExprI32x4UConvertF32x4)
 
-// Skip FP operations on NaNs or whose expected result is a NaN or so small
-// that denormalized numbers may flush to zero and cause exact FP comparisons
-// to fail.
-// TODO(bbudge) Switch FP comparisons in WASM code to WASM code that handles
-// NaNs and results with limited precision.
-bool SkipFPTestInput(float x) { return std::isnan(x); }
-
-bool SkipFPTestResult(float x) {
-  if (std::isnan(x)) return true;
-  // Constant empirically determined so existing tests pass on ARM hardware.
-  const float kSmallFloatThreshold = 1.0e-32f;
+// Skip FP operations on extremely large or extremely small values, which may
+// cause tests to fail due to non-IEEE-754 arithmetic on some platforms.
+bool SkipFPTestInput(float x) {

[Mircea Trofin, 2017/03/08 21:57:21]

We should think about what our portability story is here. Offline, we talked
about possibly having an interned API that tests the CPU capability. Then, the
test can be evaluated at JIT time and elided, together with the path that won't
be taken.

   float abs_x = std::fabs(x);
-  return abs_x != 0 && abs_x < kSmallFloatThreshold;
+  const float kSmallFloatThreshold = 1.0e-32f;
+  const float kLargeFloatThreshold = 1.0e32f;
+  return abs_x != 0.0f &&  // 0 or -0 are fine.
+         (abs_x < kSmallFloatThreshold || abs_x > kLargeFloatThreshold);
 }
 
+// Skip tests where the expected value is a NaN. Our WASM test code can't
+// deal with NaNs.
+bool SkipFPExpectedValue(float x) { return std::isnan(x); }
+
 #if V8_TARGET_ARCH_ARM || SIMD_LOWERING_TARGET
 WASM_EXEC_COMPILED_TEST(F32x4Splat) {
   FLAG_wasm_simd_prototype = true;
@@ -401,7 +400,7 @@ WASM_EXEC_COMPILED_TEST(F32x4Splat) {
         WASM_SIMD_CHECK_SPLAT_F32x4(simd, lane_val), WASM_RETURN1(WASM_ONE));
 
   FOR_FLOAT32_INPUTS(i) {
-    if (SkipFPTestInput(*i)) continue;
+    if (SkipFPExpectedValue(*i)) continue;
     CHECK_EQ(1, r.Call(*i));
   }
 }
@@ -473,7 +472,7 @@ void RunF32x4UnOpTest(WasmOpcode simd_op, FloatUnOp expected_op,
   FOR_FLOAT32_INPUTS(i) {
     if (SkipFPTestInput(*i)) continue;
     float expected = expected_op(*i);
-    if (SkipFPTestResult(expected)) continue;
+    if (SkipFPExpectedValue(expected)) continue;
     float abs_error = std::abs(expected) * error;
     CHECK_EQ(1, r.Call(*i, expected - abs_error, expected + abs_error));
   }
@@ -519,7 +518,7 @@ void RunF32x4BinOpTest(WasmOpcode simd_op, FloatBinOp expected_op) {
     FOR_FLOAT32_INPUTS(j) {
       if (SkipFPTestInput(*j)) continue;
       float expected = expected_op(*i, *j);
-      if (SkipFPTestResult(expected)) continue;
+      if (SkipFPExpectedValue(expected)) continue;
       CHECK_EQ(1, r.Call(*i, *j, expected));
     }
   }
@@ -572,7 +571,7 @@ void RunF32x4CompareOpTest(WasmOpcode simd_op, FloatCompareOp expected_op) {
     FOR_FLOAT32_INPUTS(j) {
       if (SkipFPTestInput(*j)) continue;
       float diff = *i - *j;
-      if (SkipFPTestResult(diff)) continue;
+      if (SkipFPExpectedValue(diff)) continue;
       CHECK_EQ(1, r.Call(*i, *j, expected_op(*i, *j)));
     }
   }