Changeset 205566 in webkit

Timestamp:

Sep 7, 2016 1:21:46 PM (8 years ago)

Author:

fpizlo@apple.com

Message:

Make emitAllocateWithNonNullAllocator's sub32() disallow-scratch-friendly
​https://bugs.webkit.org/show_bug.cgi?id=161706

Reviewed by Geoffrey Garen.

You can't sub32(Addr, Reg) on not-x86 without using a scratch register. So, on those CPUs, we
have to do something different.

• jit/AssemblyHelpers.h:

(JSC::AssemblyHelpers::emitAllocateWithNonNullAllocator):

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• jit/AssemblyHelpers.h (modified) (1 diff)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2016-09-07  Filip Pizlo  <fpizlo@apple.com>
+
+        Make emitAllocateWithNonNullAllocator's sub32() disallow-scratch-friendly
+        https://bugs.webkit.org/show_bug.cgi?id=161706
+
+        Reviewed by Geoffrey Garen.
+        
+        You can't sub32(Addr, Reg) on not-x86 without using a scratch register. So, on those CPUs, we
+        have to do something different.
+
+        * jit/AssemblyHelpers.h:
+        (JSC::AssemblyHelpers::emitAllocateWithNonNullAllocator):
+
 2016-09-07  Michael Catanzaro  <mcatanzaro@igalia.com>
 

trunk/Source/JavaScriptCore/jit/AssemblyHelpers.h

@@ -1428 +1428 @@
             add32(TrustedImm32(-allocator->cellSize()), resultGPR, scratchGPR);
         else {
-            move(resultGPR, scratchGPR);
-            sub32(Address(allocatorGPR, MarkedAllocator::offsetOfCellSize()), scratchGPR);
+            if (isX86()) {
+                move(resultGPR, scratchGPR);
+                sub32(Address(allocatorGPR, MarkedAllocator::offsetOfCellSize()), scratchGPR);
+            } else {
+                // FIXME: We need a 3-operand sub, and ARM totally has it!
+                load32(Address(allocatorGPR, MarkedAllocator::offsetOfCellSize()), scratchGPR);
+                neg32(scratchGPR);
+                add32(resultGPR, scratchGPR);
+            }
         }
         negPtr(resultGPR);