Bug 871777 - Fold a load and a jump. r=jandem

js/src/ion/shared/Assembler-x86-shared.h

@@ -562,6 +562,9 @@ class AssemblerX86Shared
 
     void jmp(const Operand &op){
         switch (op.kind()) {
+          case Operand::REG_DISP:
+            masm.jmp_m(op.disp(), op.base());
+            break;
           case Operand::SCALE:
             masm.jmp_m(op.disp(), op.base(), op.index(), op.scale());
             break;

js/src/ion/x64/BaselineHelpers-x64.h

@@ -47,12 +47,8 @@ EmitEnterTypeMonitorIC(MacroAssembler &masm,
     // is properly initialized to point to the stub.
     masm.movq(Operand(BaselineStubReg, (int32_t) monitorStubOffset), BaselineStubReg);
 
-    // Load stubcode pointer from BaselineStubEntry into BaselineTailCallReg.
-    masm.movq(Operand(BaselineStubReg, (int32_t) ICStub::offsetOfStubCode()),
-              BaselineTailCallReg);
-
     // Jump to the stubcode.
-    masm.jmp(Operand(BaselineTailCallReg));
+    masm.jmp(Operand(BaselineStubReg, (int32_t) ICStub::offsetOfStubCode()));
 }
 
 inline void
@@ -270,12 +266,8 @@ EmitStubGuardFailure(MacroAssembler &masm)
     // Load next stub into BaselineStubReg
     masm.movq(Operand(BaselineStubReg, ICStub::offsetOfNext()), BaselineStubReg);
 
-    // Load stubcode pointer from BaselineStubEntry into BaselineTailCallReg
-    // BaselineTailCallReg will always be unused in the contexts where IC stub guards fail
-    masm.movq(Operand(BaselineStubReg, ICStub::offsetOfStubCode()), BaselineTailCallReg);
-
     // Return address is already loaded, just jump to the next stubcode.
-    masm.jmp(Operand(BaselineTailCallReg));
+    masm.jmp(Operand(BaselineStubReg, ICStub::offsetOfStubCode()));
 }
 
 

js/src/ion/x86/BaselineHelpers-x86.h

@@ -48,12 +48,8 @@ EmitEnterTypeMonitorIC(MacroAssembler &masm,
     // is properly initialized to point to the stub.
     masm.movl(Operand(BaselineStubReg, (int32_t) monitorStubOffset), BaselineStubReg);
 
-    // Load stubcode pointer from BaselineStubReg into BaselineTailCallReg.
-    masm.movl(Operand(BaselineStubReg, (int32_t) ICStub::offsetOfStubCode()),
-              BaselineTailCallReg);
-
     // Jump to the stubcode.
-    masm.jmp(Operand(BaselineTailCallReg));
+    masm.jmp(Operand(BaselineStubReg, (int32_t) ICStub::offsetOfStubCode()));
 }
 
 inline void
@@ -276,13 +272,8 @@ EmitStubGuardFailure(MacroAssembler &masm)
     // Load next stub into BaselineStubReg
     masm.movl(Operand(BaselineStubReg, (int32_t) ICStub::offsetOfNext()), BaselineStubReg);
 
-    // Load stubcode pointer from BaselineStubEntry into BaselineTailCallReg
-    // BaselineTailCallReg will always be unused in the contexts where IC stub guards fail
-    masm.movl(Operand(BaselineStubReg, (int32_t) ICStub::offsetOfStubCode()),
-              BaselineTailCallReg);
-
     // Return address is already loaded, just jump to the next stubcode.
-    masm.jmp(Operand(BaselineTailCallReg));
+    masm.jmp(Operand(BaselineStubReg, (int32_t) ICStub::offsetOfStubCode()));
 }