[crankshaft] Fix DoDeferredMathAbsTaggedHeapNumber overwriting the context with some temporary valu…

src/crankshaft/x64/lithium-codegen-x64.cc

Index: src/crankshaft/x64/lithium-codegen-x64.cc
diff --git a/src/crankshaft/x64/lithium-codegen-x64.cc b/src/crankshaft/x64/lithium-codegen-x64.cc
index 493bfd49f43f7e8b6f50de39c3a30055d3ba6365..70aec0da60bf744ce8cf8036e20df57c79cfa5b0 100644
--- a/src/crankshaft/x64/lithium-codegen-x64.cc
+++ b/src/crankshaft/x64/lithium-codegen-x64.cc
@@ -3270,6 +3270,17 @@ void LCodeGen::DoDeferredMathAbsTaggedHeapNumber(LMathAbs* instr) {
   Register tmp = input_reg.is(rax) ? rcx : rax;
   Register tmp2 = tmp.is(rcx) ? rdx : input_reg.is(rcx) ? rdx : rcx;
 
+  // Make sure that the context isn't overwritten in the AllocateHeapNumber
+  // macro below.
+  if (instr->context()->IsRegister()) {
+    Register context_reg = ToRegister(instr->context());
+    if (tmp.is(context_reg)) {
+      tmp = rbx;
+    } else if (tmp2.is(context_reg)) {
+      tmp2 = rbx;
+    }
+  }
+
   // Preserve the value of all registers.
   PushSafepointRegistersScope scope(this);