Try inlining the LdGblAddr(Def) helpers

LdGblAddr and LdGblAddrDef call helpers that are really thin
wrappers.  Seems like it might be a good idea to just emit code
directly into the TC to avoid the extra call.

hphp/runtime/vm/translator/hopt/codegen.cpp

@@ -4651,27 +4651,40 @@ void CodeGenerator::cgAKExists(IRInstruction* inst) {
                ArgGroup(m_regs).ssa(key).ssa(arr));
 }
 
-HOT_FUNC_VM static TypedValue* ldGblAddrHelper(StringData* name) {
-  return g_vmContext->m_globalVarEnv->lookup(name);
-}
-
-HOT_FUNC_VM static TypedValue* ldGblAddrDefHelper(StringData* name) {
-  TypedValue* r = g_vmContext->m_globalVarEnv->lookupAdd(name);
-  decRefStr(name);
-  return r;
-}
-
 void CodeGenerator::cgLdGblAddr(IRInstruction* inst) {
   auto dstReg = m_regs[inst->getDst()].getReg();
-  cgCallHelper(m_as, (TCA)ldGblAddrHelper, dstReg, kNoSyncPoint,
-               ArgGroup(m_regs).ssa(inst->getSrc(0)));
+  auto rEC = rScratch;
+  // TODO(#2384005): If we create separate opcodes for loading the VM
+  // context and the global variable environment we may find some CSE
+  // opportunities that aren't currently exploited.
+  emitGetGContext(m_as, rEC);
+  m_as.loadq(rEC[offsetof(VMExecutionContext, m_globalVarEnv)], rEC);
+  ArgGroup args = ArgGroup(m_regs)
+    .reg(rEC)
+    .ssa(inst->getSrc(0));
+  cgCallHelper(m_as,
+               (TCA)getMethodPtr(&VarEnv::lookup),
+               dstReg,
+               kNoSyncPoint,
+               args);
   m_as.testq(dstReg, dstReg);
   emitFwdJcc(CC_Z, inst->getTaken());
 }
 
 void CodeGenerator::cgLdGblAddrDef(IRInstruction* inst) {
-  cgCallHelper(m_as, (TCA)ldGblAddrDefHelper, inst->getDst(), kNoSyncPoint,
-               ArgGroup(m_regs).ssa(inst->getSrc(0)));
+  auto dstReg = m_regs[inst->getDst()].getReg();
+  auto rEC = rScratch;
+  // TODO(#2384005): see LdGblAddr
+  emitGetGContext(m_as, rEC);
+  m_as.loadq(rEC[offsetof(VMExecutionContext, m_globalVarEnv)], rEC);
+  ArgGroup args = ArgGroup(m_regs)
+    .reg(rEC)
+    .ssa(inst->getSrc(0));
+  cgCallHelper(m_as,
+               (TCA)getMethodPtr(&VarEnv::lookupAdd),
+               dstReg,
+               kNoSyncPoint,
+               args);
 }
 
 void CodeGenerator::cgJmpZeroHelper(IRInstruction* inst,

hphp/runtime/vm/translator/hopt/hhbctranslator.cpp

@@ -1200,7 +1200,10 @@ SSATmp* HhbcTranslator::emitLdGblAddr(const StringData* gblName, Block* block) {
 }
 
 SSATmp* HhbcTranslator::emitLdGblAddrDef(const StringData* gblName) {
-  return gen(LdGblAddrDef, getStrName(gblName));
+  SSATmp* name = getStrName(gblName);
+  SSATmp* addr = gen(LdGblAddrDef, name);
+  gen(DecRef, name);
+  return addr;
 }
 
 void HhbcTranslator::emitIncDecS(bool pre, bool inc) {

hphp/runtime/vm/translator/translator-x64.cpp

@@ -891,7 +891,7 @@ void TranslatorX64::emitIncRefGeneric(PhysReg base, int disp) {
   emitIncRefGenericRegSafe(base, disp, r(tmpReg));
 }
 
-static void emitGetGContext(X64Assembler& a, PhysReg dest) {
+void emitGetGContext(X64Assembler& a, PhysReg dest) {
   emitTLSLoad<ExecutionContext>(a, g_context, dest);
 }
 

hphp/runtime/vm/translator/translator-x64.h

@@ -1186,6 +1186,8 @@ bool classIsUnique(const Class* cls);
 bool classIsUniqueOrCtxParent(const Class* cls);
 bool classIsUniqueNormalClass(const Class* cls);
 
+void emitGetGContext(X64Assembler& a, PhysReg dest);
+
 // SpaceRecorder is used in translator-x64.cpp and in hopt/irtranslator.cpp
 // RAII logger for TC space consumption.
 struct SpaceRecorder {