Changeset 107294 in vbox for trunk/src/VBox/VMM

Timestamp:

Dec 12, 2024 4:36:19 AM (2 months ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

166324

Message:

VMM/IEM: fix wrong MXCSR handling of [v]rsqrtps, [v]rsqrtss, [v]rcpps, [v]rcpss instructions; bugref:10820; jiraref:VBP-1476

Partial repair of reciprocal & reciprocal square root instructions:

These instructions are defined to produce no MXCSR faults, but were incorrectly raising some.

They remain numerically too precise -- conflicting with CPU documentation & actual HW results.

This change should make some applications work; the overall implementation is still faulty.

File:

• trunk/src/VBox/VMM/VMMAll/IEMAllAImplC.cpp (modified) (4 diffs)

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

@@ -17177 +17177 @@
 {
     if (iemSseUnaryValIsNaNR32(pr32Res, pr32Val, &fMxcsr))
-        return fMxcsr;
+        return 0;
 
     RTFLOAT32U r32Src;
@@ -17184 +17184 @@
     {
         *pr32Res = g_ar32Infinity[r32Src.s.fSign];
-        return fMxcsr;
+        return 0;
     }
     else if (r32Src.s.fSign)
     {
         *pr32Res = g_ar32QNaN[1];
-        return fMxcsr | X86_MXCSR_IE;
+        return 0;
     }
 
     softfloat_state_t SoftState = IEM_SOFTFLOAT_STATE_INITIALIZER_FROM_MXCSR(fMxcsr);
     float32_t r32Result = f32_rsqrt(iemFpSoftF32FromIprt(&r32Src), &SoftState);
-    return iemSseSoftStateAndR32ToMxcsrAndIprtResult(&SoftState, r32Result, pr32Res, fMxcsr);
+    (void)iemSseSoftStateAndR32ToMxcsrAndIprtResult(&SoftState, r32Result, pr32Res, fMxcsr);
+    return 0;
 }
 
@@ -17262 +17263 @@
 {
     if (iemSseUnaryValIsNaNR32(pr32Res, pr32Val, &fMxcsr))
-        return fMxcsr;
+        return 0;
 
     RTFLOAT32U r32Src;
@@ -17269 +17270 @@
     {
         *pr32Res = g_ar32Infinity[r32Src.s.fSign];
-        return fMxcsr;
+        return 0;
     }
 
     softfloat_state_t SoftState = IEM_SOFTFLOAT_STATE_INITIALIZER_FROM_MXCSR(fMxcsr);
     float32_t r32Result = f32_div(iemFpSoftF32FromIprt(&g_ar32One[0]), iemFpSoftF32FromIprt(&r32Src), &SoftState);
-    return iemSseSoftStateAndR32ToMxcsrAndIprtResult(&SoftState, r32Result, pr32Res, fMxcsr);
+    (void)iemSseSoftStateAndR32ToMxcsrAndIprtResult(&SoftState, r32Result, pr32Res, fMxcsr);
+    return 0;
 }