Changeset 191763 in webkit

Timestamp:

Oct 29, 2015 4:43:42 PM (9 years ago)

Author:

fpizlo@apple.com

Message:

B3::LowerToAir::imm() should work for both 32-bit and 64-bit immediates
​https://bugs.webkit.org/show_bug.cgi?id=150685

Reviewed by Geoffrey Garen.

In B3, a constant must match the type of its use. In Air, immediates don't have type, they
only have representation. A 32-bit immediate (i.e. Arg::imm) can be used either for 32-bit
operations or for 64-bit operations. The only difference from a Arg::imm64 is that it
requires fewer bits.

In the B3->Air lowering, we have a lot of code that is effectively polymorphic over integer
type. That code should still be able to use Arg::imm, and it should work even for 64-bit
immediates - so long as they are representable as 32-bit immediates. Therefore, the imm()
helper should happily accept either Const32Value or Const64Value.

We already sort of had this with immAnyType(), but it just turns out that anyone using
immAnyType() should really be using imm().

• b3/B3LowerToAir.cpp:

(JSC::B3::Air::LowerToAir::imm):
(JSC::B3::Air::LowerToAir::tryStore):
(JSC::B3::Air::LowerToAir::tryConst64):
(JSC::B3::Air::LowerToAir::immAnyInt): Deleted.

• b3/testb3.cpp:

(JSC::B3::testAdd1):
(JSC::B3::testAdd1Ptr):
(JSC::B3::testStoreAddLoad):
(JSC::B3::run):

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• b3/B3LowerToAir.cpp (modified) (3 diffs)
• b3/testb3.cpp (modified) (2 diffs)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2015-10-29  Filip Pizlo  <fpizlo@apple.com>
+
+        B3::LowerToAir::imm() should work for both 32-bit and 64-bit immediates
+        https://bugs.webkit.org/show_bug.cgi?id=150685
+
+        Reviewed by Geoffrey Garen.
+
+        In B3, a constant must match the type of its use. In Air, immediates don't have type, they
+        only have representation. A 32-bit immediate (i.e. Arg::imm) can be used either for 32-bit
+        operations or for 64-bit operations. The only difference from a Arg::imm64 is that it
+        requires fewer bits.
+
+        In the B3->Air lowering, we have a lot of code that is effectively polymorphic over integer
+        type. That code should still be able to use Arg::imm, and it should work even for 64-bit
+        immediates - so long as they are representable as 32-bit immediates. Therefore, the imm()
+        helper should happily accept either Const32Value or Const64Value.
+
+        We already sort of had this with immAnyType(), but it just turns out that anyone using
+        immAnyType() should really be using imm().
+
+        * b3/B3LowerToAir.cpp:
+        (JSC::B3::Air::LowerToAir::imm):
+        (JSC::B3::Air::LowerToAir::tryStore):
+        (JSC::B3::Air::LowerToAir::tryConst64):
+        (JSC::B3::Air::LowerToAir::immAnyInt): Deleted.
+        * b3/testb3.cpp:
+        (JSC::B3::testAdd1):
+        (JSC::B3::testAdd1Ptr):
+        (JSC::B3::testStoreAddLoad):
+        (JSC::B3::run):
+
 2015-10-29  Filip Pizlo  <fpizlo@apple.com>
 

trunk/Source/JavaScriptCore/b3/B3LowerToAir.cpp

@@ -218 +218 @@
     Arg imm(Value* value)
     {
-        if (value->hasInt32())
-            return Arg::imm(value->asInt32());
-        return Arg();
-    }
-
-    Arg immAnyInt(Value* value)
-    {
         if (value->hasInt()) {
             int64_t fullValue = value->asInt();
@@ -601 +594 @@
         Arg destination = effectiveAddr(address);
 
-        Arg imm = immAnyInt(value);
-        if (imm && isValidForm(move, Arg::Imm, destination.kind())) {
-            append(moveForType(value->type()), imm, effectiveAddr(address, currentValue));
+        if (imm(value) && isValidForm(move, Arg::Imm, destination.kind())) {
+            append(moveForType(value->type()), imm(value), effectiveAddr(address, currentValue));
             return true;
         }
@@ -643 +635 @@
     bool tryConst64()
     {
+        if (imm(currentValue)) {
+            append(Move, imm(currentValue), tmp(currentValue));
+            return true;
+        }
         append(Move, Arg::imm64(currentValue->asInt64()), tmp(currentValue));
         return true;

trunk/Source/JavaScriptCore/b3/testb3.cpp

@@ -215 +215 @@
 }
 
+void testAdd1Ptr(intptr_t value)
+{
+    Procedure proc;
+    BasicBlock* root = proc.addBlock();
+    root->appendNew<ControlValue>(
+        proc, Return, Origin(),
+        root->appendNew<Value>(
+            proc, Add, Origin(),
+            root->appendNew<ArgumentRegValue>(proc, Origin(), GPRInfo::argumentGPR0),
+            root->appendNew<ConstPtrValue>(proc, Origin(), 1)));
+
+    CHECK(compileAndRun<intptr_t>(proc, value) == value + 1);
+}
+
 void testStoreAddLoad(int amount)
 {
@@ -503 +517 @@
     RUN(testTrunc((static_cast<int64_t>(1) << 40) + 42));
     RUN(testAdd1(45));
+    RUN(testAdd1Ptr(51));
+    RUN(testAdd1Ptr(bitwise_cast<intptr_t>(vm)));
     RUN(testStoreAddLoad(46));
     RUN(testStoreAddLoadInterference(52));