From 7cad99bba1372d10233eb2277057aa18f787c060 Mon Sep 17 00:00:00 2001
From: Jan de Mooij <jdemooij@mozilla.com>
Date: Tue, 22 Jan 2013 14:33:36 +0100
Subject: [PATCH] Bug 831754 part 2 - Add patchable call instruction, x86/x64
 part. r=dvander a=nonlibxul

---
 js/src/ion/shared/Assembler-x86-shared.h | 6 ++++++
 js/src/ion/x64/Assembler-x64.h           | 9 +++++++++
 js/src/ion/x86/Assembler-x86.h           | 9 +++++++++
 3 files changed, 24 insertions(+)

diff --git a/js/src/ion/shared/Assembler-x86-shared.h b/js/src/ion/shared/Assembler-x86-shared.h
index a2cec5e3bd8..3d48e0a55ca 100644
--- a/js/src/ion/shared/Assembler-x86-shared.h
+++ b/js/src/ion/shared/Assembler-x86-shared.h
@@ -1246,6 +1246,12 @@ class AssemblerX86Shared
         JS_ASSERT(*ptr == 0xE9);
         *ptr = 0x3D;
     }
+    static void ToggleCall(CodeLocationLabel inst, bool enabled) {
+        uint8_t *ptr = (uint8_t *)inst.raw();
+        JS_ASSERT(*ptr == 0x3D || // CMP
+                  *ptr == 0xE8);  // CALL
+        *ptr = enabled ? 0xE8 : 0x3D;
+    }
 };
 
 } // namespace ion
diff --git a/js/src/ion/x64/Assembler-x64.h b/js/src/ion/x64/Assembler-x64.h
index 27940bdccc1..e0ba264d6e2 100644
--- a/js/src/ion/x64/Assembler-x64.h
+++ b/js/src/ion/x64/Assembler-x64.h
@@ -558,6 +558,15 @@ class Assembler : public AssemblerX86Shared
         addPendingJump(src, target->raw(), Relocation::IONCODE);
     }
 
+    // Emit a CALL or CMP (nop) instruction. ToggleCall can be used to patch
+    // this instruction.
+    CodeOffsetLabel toggledCall(IonCode *target, bool enabled) {
+        CodeOffsetLabel offset(size());
+        JmpSrc src = enabled ? masm.call() : masm.cmp_eax();
+        addPendingJump(src, target->raw(), Relocation::IONCODE);
+        return offset;
+    }
+
     // Do not mask shared implementations.
     using AssemblerX86Shared::call;
 
diff --git a/js/src/ion/x86/Assembler-x86.h b/js/src/ion/x86/Assembler-x86.h
index 2113c6e3efa..0456c5e6e73 100644
--- a/js/src/ion/x86/Assembler-x86.h
+++ b/js/src/ion/x86/Assembler-x86.h
@@ -369,6 +369,15 @@ class Assembler : public AssemblerX86Shared
         addPendingJump(src, target.asPointer(), Relocation::HARDCODED);
     }
 
+    // Emit a CALL or CMP (nop) instruction. ToggleCall can be used to patch
+    // this instruction.
+    CodeOffsetLabel toggledCall(IonCode *target, bool enabled) {
+        CodeOffsetLabel offset(size());
+        JmpSrc src = enabled ? masm.call() : masm.cmp_eax();
+        addPendingJump(src, target->raw(), Relocation::IONCODE);
+        return offset;
+    }
+
     // Re-routes pending jumps to an external target, flushing the label in the
     // process.
     void retarget(Label *label, void *target, Relocation::Kind reloc) {