Changeset 195578 in webkit

Timestamp:

Jan 25, 2016 8:01:33 PM (8 years ago)

Author:

commit-queue@webkit.org

Message:

[JSC] We should never use x18 on iOS ARM64
​https://bugs.webkit.org/show_bug.cgi?id=153461

Patch by Benjamin Poulain <​bpoulain@apple.com> on 2016-01-25
Reviewed by Filip Pizlo.

The register x18 is reserved in the iOS variant of the ARM64 ABI.

The weird thing is: if you use it, its value will change completely
randomly. It looks like it is changed by the system on interrupts.

This patch adds x18 to the reserved register and add assertions
to the assembler to prevent similar problems in the future.

• assembler/ARM64Assembler.h:

(JSC::ARM64Assembler::xOrSp):
(JSC::ARM64Assembler::xOrZr):

• assembler/AbstractMacroAssembler.h:

(JSC::isIOS): Deleted.

• assembler/AssemblerCommon.h:

(JSC::isIOS):

• jit/RegisterSet.cpp:

(JSC::RegisterSet::reservedHardwareRegisters):

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• assembler/ARM64Assembler.h (modified) (1 diff)
• assembler/AbstractMacroAssembler.h (modified) (1 diff)
• assembler/AssemblerCommon.h (modified) (1 diff)
• jit/RegisterSet.cpp (modified) (1 diff)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2016-01-25  Benjamin Poulain  <bpoulain@apple.com>
+
+        [JSC] We should never use x18 on iOS ARM64
+        https://bugs.webkit.org/show_bug.cgi?id=153461
+
+        Reviewed by Filip Pizlo.
+
+        The register x18 is reserved in the iOS variant of the ARM64 ABI.
+
+        The weird thing is: if you use it, its value will change completely
+        randomly. It looks like it is changed by the system on interrupts.
+
+        This patch adds x18 to the reserved register and add assertions
+        to the assembler to prevent similar problems in the future.
+
+        * assembler/ARM64Assembler.h:
+        (JSC::ARM64Assembler::xOrSp):
+        (JSC::ARM64Assembler::xOrZr):
+        * assembler/AbstractMacroAssembler.h:
+        (JSC::isIOS): Deleted.
+        * assembler/AssemblerCommon.h:
+        (JSC::isIOS):
+        * jit/RegisterSet.cpp:
+        (JSC::RegisterSet::reservedHardwareRegisters):
+
 2016-01-25  Commit Queue  <commit-queue@webkit.org>
 

trunk/Source/JavaScriptCore/assembler/ARM64Assembler.h

@@ -3277 +3277 @@
     }
 
-    static int xOrSp(RegisterID reg) { ASSERT(!isZr(reg)); return reg; }
-    static int xOrZr(RegisterID reg) { ASSERT(!isSp(reg)); return reg & 31; }
+    static int xOrSp(RegisterID reg)
+    {
+        ASSERT(!isZr(reg));
+        ASSERT(!isIOS() || reg != ARM64Registers::x18);
+        return reg;
+    }
+    static int xOrZr(RegisterID reg)
+    {
+        ASSERT(!isSp(reg));
+        ASSERT(!isIOS() || reg != ARM64Registers::x18);
+        return reg & 31;
+    }
     static FPRegisterID xOrZrAsFPR(RegisterID reg) { return static_cast<FPRegisterID>(xOrZr(reg)); }
     static int xOrZrOrSp(bool useZr, RegisterID reg) { return useZr ? xOrZr(reg) : xOrSp(reg); }

trunk/Source/JavaScriptCore/assembler/AbstractMacroAssembler.h

@@ -77 +77 @@
 }
 
-inline bool isIOS()
-{
-#if PLATFORM(IOS)
-    return true;
-#else
-    return false;
-#endif
-}
-
 inline bool optimizeForARMv7IDIVSupported()
 {

trunk/Source/JavaScriptCore/assembler/AssemblerCommon.h

@@ -28 +28 @@
 
 namespace JSC {
+
+ALWAYS_INLINE bool isIOS()
+{
+#if PLATFORM(IOS)
+    return true;
+#else
+    return false;
+#endif
+}
 
 ALWAYS_INLINE bool isInt9(int32_t value)

trunk/Source/JavaScriptCore/jit/RegisterSet.cpp

@@ -46 +46 @@
 {
 #if CPU(ARM64)
+#if PLATFORM(IOS)
+    return RegisterSet(ARM64Registers::x18, ARM64Registers::lr);
+#else
     return RegisterSet(ARM64Registers::lr);
+#endif // PLATFORM(IOS)
 #else
     return RegisterSet();