Merged: [crankshaft] Range analysis should not rely on overflowed ranges.

src/crankshaft/hydrogen-instructions.cc

Index: src/crankshaft/hydrogen-instructions.cc
diff --git a/src/crankshaft/hydrogen-instructions.cc b/src/crankshaft/hydrogen-instructions.cc
index 0e56d757fdd77b847b0c2b21ba75c66d469d588d..3a0aaa70e7345947537314a806bbcf1a855e8b80 100644
--- a/src/crankshaft/hydrogen-instructions.cc
+++ b/src/crankshaft/hydrogen-instructions.cc
@@ -259,7 +259,11 @@ bool Range::AddAndCheckOverflow(const Representation& r, Range* other) {
   bool may_overflow = false;
   lower_ = AddWithoutOverflow(r, lower_, other->lower(), &may_overflow);
   upper_ = AddWithoutOverflow(r, upper_, other->upper(), &may_overflow);
-  KeepOrder();
+  if (may_overflow) {
+    Clear();
+  } else {
+    KeepOrder();
+  }
 #ifdef DEBUG
   Verify();
 #endif
@@ -271,13 +275,21 @@ bool Range::SubAndCheckOverflow(const Representation& r, Range* other) {
   bool may_overflow = false;
   lower_ = SubWithoutOverflow(r, lower_, other->upper(), &may_overflow);
   upper_ = SubWithoutOverflow(r, upper_, other->lower(), &may_overflow);
-  KeepOrder();
+  if (may_overflow) {
+    Clear();
+  } else {
+    KeepOrder();
+  }
 #ifdef DEBUG
   Verify();
 #endif
   return may_overflow;
 }
 
+void Range::Clear() {
+  lower_ = kMinInt;
+  upper_ = kMaxInt;
+}
 
 void Range::KeepOrder() {
   if (lower_ > upper_) {
@@ -301,8 +313,12 @@ bool Range::MulAndCheckOverflow(const Representation& r, Range* other) {
   int v2 = MulWithoutOverflow(r, lower_, other->upper(), &may_overflow);
   int v3 = MulWithoutOverflow(r, upper_, other->lower(), &may_overflow);
   int v4 = MulWithoutOverflow(r, upper_, other->upper(), &may_overflow);
-  lower_ = Min(Min(v1, v2), Min(v3, v4));
-  upper_ = Max(Max(v1, v2), Max(v3, v4));
+  if (may_overflow) {
+    Clear();
+  } else {
+    lower_ = Min(Min(v1, v2), Min(v3, v4));
+    upper_ = Max(Max(v1, v2), Max(v3, v4));
+  }
 #ifdef DEBUG
   Verify();
 #endif