src/hotspot/cpu/x86/vm_version_x86.cpp

rev 52433 : 8213538: VM crashes when MaxVectorSize is set to 0, 1 or 2
Summary: Require MaxVectorSize minimum 4 on 64 bit
Reviewed-by:

*** 982,1029 ****
        // Only supported with SSE2+
        FLAG_SET_DEFAULT(UseFPUForSpilling, false);
      }
    }
  #endif
  #if COMPILER2_OR_JVMCI
!   if (MaxVectorSize > 0) {
!     if (!is_power_of_2(MaxVectorSize)) {
!       warning("MaxVectorSize must be a power of 2");
!       FLAG_SET_DEFAULT(MaxVectorSize, 64);
!     }
      if (UseSSE < 2) {
        // Vectors (in XMM) are only supported with SSE2+
!       if (MaxVectorSize > 0) {
!         if (!FLAG_IS_DEFAULT(MaxVectorSize))
!           warning("MaxVectorSize must be 0");
!         FLAG_SET_DEFAULT(MaxVectorSize, 0);
!       }
!     }
!     else if (UseAVX == 0 || !os_supports_avx_vectors()) {
        // 32 bytes vectors (in YMM) are only supported with AVX+
!       if (MaxVectorSize > 16) {
!         if (!FLAG_IS_DEFAULT(MaxVectorSize))
!           warning("MaxVectorSize must be <= 16");
!         FLAG_SET_DEFAULT(MaxVectorSize, 16);
!       }
!     }
!     else if (UseAVX == 1 || UseAVX == 2) {
        // 64 bytes vectors (in ZMM) are only supported with AVX 3
!       if (MaxVectorSize > 32) {
!         if (!FLAG_IS_DEFAULT(MaxVectorSize))
!           warning("MaxVectorSize must be <= 32");
!         FLAG_SET_DEFAULT(MaxVectorSize, 32);
        }
      }
!     else if (UseAVX > 2 ) {
!       if (MaxVectorSize > 64) {
!         if (!FLAG_IS_DEFAULT(MaxVectorSize))
!           warning("MaxVectorSize must be <= 64");
!         FLAG_SET_DEFAULT(MaxVectorSize, 64);
        }
      }
  #if defined(COMPILER2) && defined(ASSERT)
      if (supports_avx() && PrintMiscellaneous && Verbose && TraceNewVectors) {
        tty->print_cr("State of YMM registers after signal handle:");
        int nreg = 2 LP64_ONLY(+2);
        const char* ymm_name[4] = {"0", "7", "8", "15"};
        for (int i = 0; i < nreg; i++) {
--- 982,1034 ----
        // Only supported with SSE2+
        FLAG_SET_DEFAULT(UseFPUForSpilling, false);
      }
    }
  #endif
+ 
  #if COMPILER2_OR_JVMCI
!   int mvs_max = 0;
    if (UseSSE < 2) {
      // Vectors (in XMM) are only supported with SSE2+
!     // SSE is always 2 on x64.
!     mvs_max = 0;
!   } else if (UseAVX == 0 || !os_supports_avx_vectors()) {
!     // 16 byte vectors (in XMM) are supported with SSE2+
!     mvs_max = 16;
!   } else if (UseAVX == 1 || UseAVX == 2) {
      // 32 bytes vectors (in YMM) are only supported with AVX+
!     mvs_max = 32;
!   } else if (UseAVX > 2 ) {
      // 64 bytes vectors (in ZMM) are only supported with AVX 3
!     mvs_max = 64;
    }
+ 
+   int mvs_min = 0;
+ #ifdef _LP64
+   mvs_min = 4; // We require MaxVectorSize to be at least 4 on 64bit
+ #endif
+ 
+   if (!FLAG_IS_DEFAULT(MaxVectorSize)) {
+     if (MaxVectorSize < mvs_min) {
+       warning("MaxVectorSize must be at least %i on this platform", mvs_min);
+       FLAG_SET_DEFAULT(MaxVectorSize, mvs_min);
+     }
+     if (MaxVectorSize > mvs_max) {
+       warning("MaxVectorSize must be at most %i on this platform", mvs_max);
+       FLAG_SET_DEFAULT(MaxVectorSize, mvs_max);
      }
!     if (!is_power_of_2(MaxVectorSize)) {
!       warning("MaxVectorSize must be a power of 2, setting to default: %i", mvs_max);
!       FLAG_SET_DEFAULT(MaxVectorSize, mvs_max);
      }
+   } else {
+     // If default, use highest supported configuration
+     FLAG_SET_DEFAULT(MaxVectorSize, mvs_max);
    }
+ 
  #if defined(COMPILER2) && defined(ASSERT)
+   if (MaxVectorSize > 0) {
      if (supports_avx() && PrintMiscellaneous && Verbose && TraceNewVectors) {
        tty->print_cr("State of YMM registers after signal handle:");
        int nreg = 2 LP64_ONLY(+2);
        const char* ymm_name[4] = {"0", "7", "8", "15"};
        for (int i = 0; i < nreg; i++) {