JIT: Optimize "constant_string".Length

src/coreclr/src/ToolBox/superpmi/superpmi-shared/icorjitinfoimpl.h

@@ -255,6 +255,11 @@ BOOL isValidStringRef(CORINFO_MODULE_HANDLE module, /* IN  */
                       unsigned              metaTOK /* IN  */
                       );
 
+LPCWSTR getStringLiteral(CORINFO_MODULE_HANDLE module,  /* IN  */
+                         unsigned              metaTOK, /* IN  */
+                         int*                  length   /* OUT */
+                         );
+
 BOOL shouldEnforceCallvirtRestriction(CORINFO_MODULE_HANDLE scope);
 
 /**********************************************************************************/

src/coreclr/src/ToolBox/superpmi/superpmi-shared/lwmlist.h

@@ -147,6 +147,7 @@ LWM(IsInstantiationOfVerifiedGeneric, DWORDLONG, DWORD)
 LWM(IsSDArray, DWORDLONG, DWORD)
 LWM(IsStructRequiringStackAllocRetBuf, DWORDLONG, DWORD)
 LWM(IsValidStringRef, DLD, DWORD)
+LWM(GetStringLiteral, DLD, DD)
 LWM(IsValidToken, DLD, DWORD)
 LWM(IsValueClass, DWORDLONG, DWORD)
 LWM(IsWriteBarrierHelperRequired, DWORDLONG, DWORD)

src/coreclr/src/ToolBox/superpmi/superpmi-shared/methodcontext.cpp

@@ -4606,6 +4606,65 @@ BOOL MethodContext::repIsValidStringRef(CORINFO_MODULE_HANDLE module, unsigned m
     return value;
 }
 
+
+void MethodContext::recGetStringLiteral(CORINFO_MODULE_HANDLE module, unsigned metaTOK, int length, LPCWSTR result)
+{
+    if (GetStringLiteral == nullptr)
+        GetStringLiteral = new LightWeightMap<DLD, DD>();
+
+    DLD key;
+    ZeroMemory(&key, sizeof(DLD)); // We use the input structs as a key and use memcmp to compare.. so we need to zero
+                                   // out padding too
+
+    key.A = (DWORDLONG)module;
+    key.B = (DWORD)metaTOK;
+
+    DWORD strBuf = (DWORD)-1;
+    if (result != nullptr)
+        strBuf = (DWORD)GetStringLiteral->AddBuffer((unsigned char*)result, (unsigned int)((wcslen(result) * 2) + 2));
+
+    DD value;
+    value.A = (DWORD)length;
+    value.B = (DWORD)strBuf;
+
+    GetStringLiteral->Add(key, value);
+}
+
+void MethodContext::dmpGetStringLiteral(DLD key, DD value)
+{
+    printf("GetStringLiteral key mod-%016llX tok-%08X, result-%s, len-%u", key.A, key.B,
+        GetStringLiteral->GetBuffer(value.B), value.A);
+}
+
+LPCWSTR MethodContext::repGetStringLiteral(CORINFO_MODULE_HANDLE module, unsigned metaTOK, int* length)
+{
+    if (GetStringLiteral == nullptr)
+    {
+        *length = -1;
+        return nullptr;
+    }
+
+    DLD key;
+    ZeroMemory(&key, sizeof(DLD)); // We use the input structs as a key and use memcmp to compare.. so we need to zero
+                                   // out padding too
+
+    key.A = (DWORDLONG)module;
+    key.B = (DWORD)metaTOK;
+
+    int itemIndex = GetStringLiteral->GetIndex(key);
+    if (itemIndex < 0)
+    {
+        *length = -1;
+        return nullptr;
+    }
+    else
+    {
+        DD result = GetStringLiteral->Get(key);
+        *length = (int)result.A;
+        return (LPCWSTR)GetStringLiteral->GetBuffer(itemIndex);
+    }
+}
+
 void MethodContext::recGetHelperName(CorInfoHelpFunc funcNum, const char* result)
 {
     if (GetHelperName == nullptr)

src/coreclr/src/ToolBox/superpmi/superpmi-shared/methodcontext.h

@@ -1086,6 +1086,10 @@ class MethodContext
     void dmpIsValidStringRef(DLD key, DWORD value);
     BOOL repIsValidStringRef(CORINFO_MODULE_HANDLE module, unsigned metaTOK);
 
+    void recGetStringLiteral(CORINFO_MODULE_HANDLE module, unsigned metaTOK, int length, LPCWSTR result);
+    void dmpGetStringLiteral(DLD key, DD value);
+    LPCWSTR repGetStringLiteral(CORINFO_MODULE_HANDLE module, unsigned metaTOK, int* length);
+
     void recGetHelperName(CorInfoHelpFunc funcNum, const char* result);
     void dmpGetHelperName(DWORD key, DWORD value);
     const char* repGetHelperName(CorInfoHelpFunc funcNum);
@@ -1352,7 +1356,7 @@ class MethodContext
 };
 
 // ********************* Please keep this up-to-date to ease adding more ***************
-// Highest packet number: 174
+// Highest packet number: 175
 // *************************************************************************************
 enum mcPackets
 {
@@ -1493,6 +1497,7 @@ enum mcPackets
     Packet_IsSDArray                                     = 101,
     Packet_IsStructRequiringStackAllocRetBuf             = 102,
     Packet_IsValidStringRef                              = 103,
+    Packet_GetStringLiteral                              = 175, // Added 1/7/2020
     Retired6                                             = 104,
     Packet_IsValidToken                                  = 144, // Added 7/19/2013 - adjusted members to proper types
     Packet_IsValueClass                                  = 105,

src/coreclr/src/ToolBox/superpmi/superpmi-shim-collector/icorjitinfo.cpp

@@ -517,6 +517,17 @@ BOOL interceptor_ICJI::isValidStringRef(CORINFO_MODULE_HANDLE module, /* IN  */
     return temp;
 }
 
+LPCWSTR interceptor_ICJI::getStringLiteral(CORINFO_MODULE_HANDLE module,  /* IN  */
+                                           unsigned              metaTOK, /* IN  */
+                                           int*                  length   /* OUT */
+                                           )
+{
+    mc->cr->AddCall("getStringLiteral");
+    LPCWSTR temp = original_ICorJitInfo->getStringLiteral(module, metaTOK, length);
+    mc->recGetStringLiteral(module, metaTOK, *length, temp);
+    return temp;
+}
+
 BOOL interceptor_ICJI::shouldEnforceCallvirtRestriction(CORINFO_MODULE_HANDLE scope)
 {
     mc->cr->AddCall("shouldEnforceCallvirtRestriction");

src/coreclr/src/ToolBox/superpmi/superpmi-shim-counter/icorjitinfo.cpp

@@ -378,6 +378,15 @@ BOOL interceptor_ICJI::isValidStringRef(CORINFO_MODULE_HANDLE module, /* IN  */
     return original_ICorJitInfo->isValidStringRef(module, metaTOK);
 }
 
+LPCWSTR interceptor_ICJI::getStringLiteral(CORINFO_MODULE_HANDLE module,  /* IN  */
+                                           unsigned              metaTOK, /* IN  */
+                                           int*                  length   /* OUT */
+                                           )
+{
+    mcs->AddCall("getStringLiteral");
+    return original_ICorJitInfo->getStringLiteral(module, metaTOK, length);
+}
+
 BOOL interceptor_ICJI::shouldEnforceCallvirtRestriction(CORINFO_MODULE_HANDLE scope)
 {
     mcs->AddCall("shouldEnforceCallvirtRestriction");

src/coreclr/src/ToolBox/superpmi/superpmi-shim-simple/icorjitinfo.cpp

@@ -340,6 +340,14 @@ BOOL interceptor_ICJI::isValidStringRef(CORINFO_MODULE_HANDLE module, /* IN  */
     return original_ICorJitInfo->isValidStringRef(module, metaTOK);
 }
 
+LPCWSTR interceptor_ICJI::getStringLiteral(CORINFO_MODULE_HANDLE module,  /* IN  */
+                                           unsigned              metaTOK, /* IN  */
+                                           int*                  length   /* OUT */
+                                           )
+{
+    return original_ICorJitInfo->getStringLiteral(module, metaTOK, length);
+}
+
 BOOL interceptor_ICJI::shouldEnforceCallvirtRestriction(CORINFO_MODULE_HANDLE scope)
 {
     return original_ICorJitInfo->shouldEnforceCallvirtRestriction(scope);

src/coreclr/src/ToolBox/superpmi/superpmi/icorjitinfo.cpp

@@ -408,6 +408,15 @@ BOOL MyICJI::isValidStringRef(CORINFO_MODULE_HANDLE module, /* IN  */
     return jitInstance->mc->repIsValidStringRef(module, metaTOK);
 }
 
+LPCWSTR MyICJI::getStringLiteral(CORINFO_MODULE_HANDLE module,  /* IN  */
+                                 unsigned              metaTOK, /* IN  */
+                                 int*                  length   /* OUT */
+                                 )
+{
+    jitInstance->mc->cr->AddCall("getStringLiteral");
+    return jitInstance->mc->repGetStringLiteral(module, metaTOK, length);
+}
+
 BOOL MyICJI::shouldEnforceCallvirtRestriction(CORINFO_MODULE_HANDLE scope)
 {
     jitInstance->mc->cr->AddCall("shouldEnforceCallvirtRestriction");

src/coreclr/src/inc/corinfo.h

@@ -217,11 +217,11 @@ TODO: Talk about initializing strutures before use
 #endif
 #endif
 
-SELECTANY const GUID JITEEVersionIdentifier = { /* abcf830c-56d1-4b33-a8ec-5063bb5495f1 */
-    0xabcf830c,
-    0x56d1,
-    0x4b33,
-    {0xa8, 0xec, 0x50, 0x63, 0xbb, 0x54, 0x95, 0xf1}
+SELECTANY const GUID JITEEVersionIdentifier = { /* 13028353-152c-4886-b05b-fa76ee8169cf */
+    0x13028353,
+    0x152c,
+    0x4886,
+    {0xb0, 0x5b, 0xfa, 0x76, 0xee, 0x81, 0x69, 0xcf}
 };
 
 //////////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -2307,6 +2307,14 @@ class ICorStaticInfo
             unsigned                    metaTOK     /* IN  */
             ) = 0;
 
+    // Returns string length and content (can be null for dynamic context)
+    // for given metaTOK and module, length `-1` means input is incorrect
+    virtual LPCWSTR getStringLiteral (
+            CORINFO_MODULE_HANDLE       module,     /* IN  */
+            unsigned                    metaTOK,    /* IN  */
+            int*                        length      /* OUT */
+            ) = 0;
+
     virtual BOOL shouldEnforceCallvirtRestriction(
             CORINFO_MODULE_HANDLE   scope
             ) = 0;

src/coreclr/src/jit/ICorJitInfo_API_names.h

@@ -38,6 +38,7 @@ DEF_CLR_API(getTokenTypeAsHandle)
 DEF_CLR_API(canSkipVerification)
 DEF_CLR_API(isValidToken)
 DEF_CLR_API(isValidStringRef)
+DEF_CLR_API(getStringLiteral)
 DEF_CLR_API(shouldEnforceCallvirtRestriction)
 DEF_CLR_API(asCorInfoType)
 DEF_CLR_API(getClassName)

src/coreclr/src/jit/ICorJitInfo_API_wrapper.hpp

@@ -367,6 +367,17 @@ BOOL WrapICorJitInfo::isValidStringRef(
     return temp;
 }
 
+LPCWSTR WrapICorJitInfo::getStringLiteral(
+            CORINFO_MODULE_HANDLE       module,     /* IN  */
+            unsigned                    metaTOK,    /* IN  */
+            int*                        length      /* OUT */)
+{
+    API_ENTER(getStringLiteral);
+    LPCWSTR temp = wrapHnd->getStringLiteral(module, metaTOK, length);
+    API_LEAVE(getStringLiteral);
+    return temp;
+}
+
 BOOL WrapICorJitInfo::shouldEnforceCallvirtRestriction(
             CORINFO_MODULE_HANDLE   scope)
 {

src/coreclr/src/jit/importer.cpp

@@ -3632,6 +3632,27 @@ GenTree* Compiler::impIntrinsic(GenTree*                newobjThis,
             op1 = impPopStack().val;
             if (opts.OptimizationEnabled())
             {
+                if (op1->OperIs(GT_CNS_STR))
+                {
+                    // Optimize `ldstr + String::get_Length()` to CNS_INT
+                    // e.g. "Hello".Length => 5
+                    int     length = -1;
+                    LPCWSTR str    = info.compCompHnd->getStringLiteral(op1->AsStrCon()->gtScpHnd,
+                                                                     op1->AsStrCon()->gtSconCPX, &length);
+                    if (length >= 0)
+                    {
+                        retNode = gtNewIconNode(length);
+                        if (str != nullptr) // can be NULL for dynamic context
+                        {
+                            JITDUMP("Optimizing '\"%ws\".Length' to just '%d'\n", str, length);
+                        }
+                        else
+                        {
+                            JITDUMP("Optimizing 'CNS_STR.Length' to just '%d'\n", length);
+                        }
+                        break;
+                    }
+                }
                 GenTreeArrLen* arrLen = gtNewArrLen(TYP_INT, op1, OFFSETOF__CORINFO_String__stringLen, compCurBB);
                 op1                   = arrLen;
             }