c1_LIRAssembler_x86 bug in 64-bit Windows code (original) (raw)

Salter, Thomas A Thomas.Salter at unisys.com
Fri May 20 10:49:52 PDT 2011

When running a 64-bit JVM on Windows 7, the JVM.dll failed to load due to an exception in the following code. Since long is a 32-bit integer, the casts in the operand calculation have the effect of truncating a 64-bit address to 32 bits and then sign-extending it. The casts should be to intptr_t, not long.

I encountered this in JDK 7 build 130, but the source code is the same in build 142

In hotspot\src\cpu\x86\vm\c1_LIRAssembler_x86.cpp:

// Note: 'double' and 'long long' have 32-bits alignment on x86. static jlong* double_quadword(jlong *adr, jlong lo, jlong hi) { // Use the expression (adr)&(0xF) to provide 128-bits aligned address // of 128-bits operands for SSE instructions. jlong operand = (jlong)(((long)adr)&((long)(0xF))); // Store the value to a 128-bits operand. operand[0] = lo; operand[1] = hi; return operand; }

The corrected statement would be: jlong operand = (jlong)(((intptr_t)adr)&((intptr_t)(~0xF)));

Tom Salter | Software Engineer | Java & Middleware Development

Unisys | 476 Swedesford Road | Malvern, PA 19355 | 610-648-2568 | N385-2568

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