Changeset 106478 in vbox for trunk/src/VBox/VMM

Timestamp:

Oct 18, 2024 1:20:19 PM (3 months ago)

Author:

vboxsync

Message:

VMM/IEM: Some IEMNATIVEVAR / iemNativeVarAllocInt optimization tweaks. bugref:10720

Location:

trunk/src/VBox/VMM

Files:

• VMMAll/IEMAllN8veRecompiler.cpp (modified) (2 diffs)
• include/IEMN8veRecompiler.h (modified) (2 diffs)

trunk/src/VBox/VMM/VMMAll/IEMAllN8veRecompiler.cpp

@@ -7098 +7098 @@
  * @internal
  */
-static uint8_t iemNativeVarAllocInt(PIEMRECOMPILERSTATE pReNative, uint8_t cbType)
+DECL_INLINE_THROW(uint8_t) iemNativeVarAllocInt(PIEMRECOMPILERSTATE pReNative, uint8_t cbType)
 {
     Assert(cbType > 0 && cbType <= 64);
     unsigned const idxVar = ASMBitFirstSetU32(~pReNative->Core.bmVars) - 1;
     AssertStmt(idxVar < RT_ELEMENTS(pReNative->Core.aVars), IEMNATIVE_DO_LONGJMP(pReNative, VERR_IEM_VAR_EXHAUSTED));
+
     pReNative->Core.bmVars |= RT_BIT_32(idxVar);
-    pReNative->Core.aVars[idxVar].enmKind        = kIemNativeVarKind_Invalid;
-    pReNative->Core.aVars[idxVar].cbVar          = cbType;
-    pReNative->Core.aVars[idxVar].idxStackSlot   = UINT8_MAX;
-    pReNative->Core.aVars[idxVar].idxReg         = UINT8_MAX;
-    pReNative->Core.aVars[idxVar].uArgNo         = UINT8_MAX;
-    pReNative->Core.aVars[idxVar].idxReferrerVar = UINT8_MAX;
-    pReNative->Core.aVars[idxVar].enmGstReg      = kIemNativeGstReg_End;
-    pReNative->Core.aVars[idxVar].fRegAcquired   = false;
-    pReNative->Core.aVars[idxVar].u.uValue       = 0;
-    pReNative->Core.aVars[idxVar].fSimdReg       = false;
+
+    PIEMNATIVEVAR const pVar = &pReNative->Core.aVars[idxVar]; /* VS 2019 gets a bit weird on us otherwise. */
+#if 0
+    pVar->cbVar          = cbType;
+    pVar->enmKind        = kIemNativeVarKind_Invalid;
+    pVar->fRegAcquired   = false;
+    pVar->fSimdReg       = false;
+    pVar->idxReg         = UINT8_MAX;
+    pVar->uArgNo         = UINT8_MAX;
+    pVar->idxStackSlot   = UINT8_MAX;
+    pVar->idxReferrerVar = UINT8_MAX;
+    pVar->u.uValue       = 0;
+#else
+    /* Neither clang 15 nor VC++ 2019 is able to generate this from the above. */
+    AssertCompileMemberOffset(IEMNATIVEVAR, cbVar, 1);
+    AssertCompile((int)kIemNativeVarKind_Invalid == 0);
+    pVar->u32Init0       = (uint32_t)cbType << 8;
+    pVar->u32Init1       = UINT32_MAX;
+    pVar->u.uValue       = 0;
+#endif
     return idxVar;
 }
@@ -7822 +7833 @@
                    g_apszIemNativeHstRegNames[idxReg], g_aGstShadowInfo[enmGstReg].pszName));
         }
-        /** @todo figure this one out. We need some way of making sure the register isn't
-         * modified after this point, just in case we start writing crappy MC code. */
-        pVar->enmGstReg    = enmGstReg;
         pVar->fRegAcquired = true;
         return idxReg;

trunk/src/VBox/VMM/include/IEMN8veRecompiler.h

@@ -1563 +1563 @@
 typedef struct IEMNATIVEVAR
 {
-    /** The kind of variable. */
-    IEMNATIVEVARKIND    enmKind;
-    /** The variable size in bytes. */
-    uint8_t             cbVar;
-    /** The first stack slot (uint64_t), except for immediate and references
-     *  where it usually is UINT8_MAX. This is allocated lazily, so if a variable
-     *  has a stack slot it has been initialized and has a value.  Unused variables
-     *  has neither a stack slot nor a host register assignment. */
-    uint8_t             idxStackSlot;
-    /** The host register allocated for the variable, UINT8_MAX if not. */
-    uint8_t             idxReg;
-    /** The argument number if argument, UINT8_MAX if regular variable. */
-    uint8_t             uArgNo;
-    /** If referenced, the index (unpacked) of the variable referencing this one,
-     * otherwise UINT8_MAX.  A referenced variable must only be placed on the stack
-     * and must be either kIemNativeVarKind_Stack or kIemNativeVarKind_Immediate. */
-    uint8_t             idxReferrerVar;
-    /** Guest register being shadowed here, kIemNativeGstReg_End(/UINT8_MAX) if not.
-     * @todo not sure what this really is for...   */
-    IEMNATIVEGSTREG     enmGstReg;
-    /** Flag whether this variable is held in a SIMD register (only supported for 128-bit and 256-bit variables),
-     * only valid when idxReg is not UINT8_MAX. */
-    bool                fSimdReg     : 1;
-    /** Set if the registered is currently used exclusively, false if the
-     *  variable is idle and the register can be grabbed. */
-    bool                fRegAcquired : 1;
+    union
+    {
+        struct
+        {
+            /** The kind of variable. */
+            IEMNATIVEVARKIND    enmKind;
+            /** The variable size in bytes. */
+            uint8_t             cbVar;
+            /** Set if the registered is currently used exclusively, false if the
+             *  variable is idle and the register can be grabbed. */
+            bool                fRegAcquired;
+            /** Flag whether this variable is held in a SIMD register (only supported for
+             * 128-bit and 256-bit variables), only valid when idxReg is not UINT8_MAX. */
+            bool                fSimdReg;
+        };
+        uint32_t        u32Init0;   /**< Init optimzation - cbVar is set, the other are initialized with zeros. */
+    };
+
+    union
+    {
+        struct
+        {
+            /** The host register allocated for the variable, UINT8_MAX if not. */
+            uint8_t             idxReg;
+            /** The argument number if argument, UINT8_MAX if regular variable. */
+            uint8_t             uArgNo;
+            /** The first stack slot (uint64_t), except for immediate and references
+             *  where it usually is UINT8_MAX. This is allocated lazily, so if a variable
+             *  has a stack slot it has been initialized and has a value.  Unused variables
+             *  has neither a stack slot nor a host register assignment. */
+            uint8_t             idxStackSlot;
+            /** If referenced, the index (unpacked) of the variable referencing this one,
+             * otherwise UINT8_MAX.  A referenced variable must only be placed on the stack
+             * and must be either kIemNativeVarKind_Stack or kIemNativeVarKind_Immediate. */
+            uint8_t             idxReferrerVar;
+        };
+        uint32_t        u32Init1;   /**< Init optimization; all these are initialized to 0xff. */
+    };
 
     union
@@ -1606 +1618 @@
     } u;
 } IEMNATIVEVAR;
+AssertCompileSize(IEMNATIVEVAR, 16);
 /** Pointer to a variable or argument. */
 typedef IEMNATIVEVAR *PIEMNATIVEVAR;