Changeset 105997 in vbox for trunk/src/VBox/VMM

Timestamp:

Sep 10, 2024 8:55:10 AM (4 months ago)

Author:

vboxsync

Message:

VMM/IEM: Introduce a ReturnZero label when using per-chunk tail code, saving one instruction per TB. (todo 16) bugref:10720

Location:

trunk/src/VBox/VMM

Files:

• VMMAll/IEMAllN8veRecompiler.cpp (modified) (9 diffs)
• include/IEMN8veRecompiler.h (modified) (1 diff)

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

@@ -2096 +2096 @@
     pReNative->Core.u64ArgVars             = UINT64_MAX;
 
-    AssertCompile(RT_ELEMENTS(pReNative->aidxUniqueLabels) == 23);
     pReNative->aidxUniqueLabels[0]         = UINT32_MAX;
     pReNative->aidxUniqueLabels[1]         = UINT32_MAX;
@@ -2120 +2119 @@
     pReNative->aidxUniqueLabels[21]        = UINT32_MAX;
     pReNative->aidxUniqueLabels[22]        = UINT32_MAX;
+#ifdef IEMNATIVE_WITH_RECOMPILER_PER_CHUNK_TAIL_CODE
+    pReNative->aidxUniqueLabels[23]        = UINT32_MAX;
+    AssertCompile(RT_ELEMENTS(pReNative->aidxUniqueLabels) == 24);
+#else
+    AssertCompile(RT_ELEMENTS(pReNative->aidxUniqueLabels) == 23);
+#endif
 
     pReNative->idxLastCheckIrqCallNo       = UINT32_MAX;
@@ -8949 +8954 @@
         STR_CASE_CMN(CheckBranchMiss);
         STR_CASE_CMN(Return);
+#ifdef IEMNATIVE_WITH_RECOMPILER_PER_CHUNK_TAIL_CODE
+        STR_CASE_CMN(ReturnZero);
+#endif
         STR_CASE_CMN(ReturnBreak);
         STR_CASE_CMN(ReturnBreakFF);
@@ -9784 +9792 @@
          * Emit the epilog code.
          */
+        aoffLabels[kIemNativeLabelType_ReturnZero] = off;
+        off = iemNativeEmitGprZero(pReNative, off, IEMNATIVE_CALL_RET_GREG);
+
         aoffLabels[kIemNativeLabelType_Return] = off;
         off = iemNativeEmitCoreEpilog(pReNative, off);
@@ -9883 +9894 @@
         /* Make sure we've generate code for all labels. */
         for (uint32_t i = kIemNativeLabelType_Invalid + 1; i < RT_ELEMENTS(aoffLabels); i++)
-            Assert(aoffLabels[i] != 0 || i == kIemNativeLabelType_Return);
-#endif
+            Assert(aoffLabels[i] != 0 || i == kIemNativeLabelType_ReturnZero);
+# endif
     }
     IEMNATIVE_CATCH_LONGJMP_BEGIN(pReNative, rc);
@@ -9922 +9933 @@
     for (uint32_t i = kIemNativeLabelType_Invalid + 1; i < RT_ELEMENTS(pCtx->apExitLabels); i++)
     {
-        Assert(aoffLabels[i] != 0 || i == kIemNativeLabelType_Return);
+        Assert(aoffLabels[i] != 0 || i == kIemNativeLabelType_ReturnZero);
         pCtx->apExitLabels[i] = &paFinalCommonCodeRx[aoffLabels[i]];
         Log10(("    apExitLabels[%u]=%p %s\n", i, pCtx->apExitLabels[i], iemNativeGetLabelName((IEMNATIVELABELTYPE)i, true)));
@@ -10180 +10191 @@
         off = iemNativeRegFlushPendingWrites(pReNative, off);
 
+#ifndef IEMNATIVE_WITH_RECOMPILER_PER_CHUNK_TAIL_CODE
         /*
          * Successful return, so clear the return register (eax, w0).
@@ -10185 +10197 @@
         off = iemNativeEmitGprZero(pReNative, off, IEMNATIVE_CALL_RET_GREG);
 
-#ifndef IEMNATIVE_WITH_RECOMPILER_PER_CHUNK_TAIL_CODE
         /*
          * Emit the epilog code.
@@ -10196 +10207 @@
          */
         //off = iemNativeEmitBrk(pReNative, off, 0x1227);
-        off = iemNativeEmitTbExit(pReNative, off, kIemNativeLabelType_Return);
+        off = iemNativeEmitTbExit(pReNative, off, kIemNativeLabelType_ReturnZero);
 #endif
 

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

@@ -501 +501 @@
     kIemNativeLabelType_ReturnWithFlags,
     kIemNativeLabelType_NonZeroRetOrPassUp,
+#ifdef IEMNATIVE_WITH_RECOMPILER_PER_CHUNK_TAIL_CODE
+    kIemNativeLabelType_ReturnZero,             /**< Sets eax/w0 to zero and returns. */
+#endif
     kIemNativeLabelType_Return,
     /** The last fixup for branches that can span almost the whole TB length.