Bug 19813 – Generated bt instruction seg faults, high 32 bits of register is garbage

Test case. Compile for 64 bit Linux with -O: /* REQUIRED_ARGS: -O */ struct BitArray { import core.bitop : btc, bts, btr, bsf, bt; size_t _len; size_t* _ptr; enum bitsPerSizeT = size_t.sizeof * 8; static size_t lenToDim(size_t len) @nogc pure nothrow @safe { return (len + (bitsPerSizeT-1)) / bitsPerSizeT; } this(in bool[] ba) nothrow pure { length = ba.length; foreach (i, b; ba) { if (b) bts(_ptr, i); else btr(_ptr, i); } } @property size_t length(size_t newlen) pure nothrow @system { if (newlen != _len) { size_t olddim = lenToDim(_len); immutable newdim = lenToDim(newlen); if (newdim != olddim) { // Create a fake array so we can use D's realloc machinery auto b = _ptr[0 .. olddim]; b.length = newdim; // realloc _ptr = b.ptr; } _len = newlen; } return _len; } int opCmp(ref BitArray a2) const @nogc pure nothrow { const lesser = this._len < a2._len ? &this : &a2; immutable fullWords = lesser._len / lesser.bitsPerSizeT; immutable endBits = lesser._len % lesser.bitsPerSizeT; auto p1 = this._ptr; auto p2 = a2._ptr; foreach (i; 0 .. fullWords) { if (p1[i] != p2[i]) { return p1[i] & (size_t(1) << bsf(p1[i] ^ p2[i])) ? 1 : -1; } } if (endBits) { immutable i = fullWords; immutable diff = p1[i] ^ p2[i]; if (diff) { immutable index = bsf(diff); if (index < endBits) { // This gets optimized into OPbtst, and was doing it incorrectly return p1[i] & (size_t(1) << index) ? 1 : -1; } } } return -1; } } int main() { bool[] ba = [1,0,1,0,1]; bool[] bd = [1,0,1,1,1]; auto a = BitArray(ba); auto d = BitArray(bd); assert(a < d); }

@WalterBright updated dlang/dmd pull request #9656 "fix Issue 19813 - Generated bt instruction seg faults, high 32 bits of register is garbage" fixing this issue: - fix Issue 19813 optimization of bit test to OPbtst https://github.com/dlang/dmd/pull/9656

dlang/dmd pull request #9656 "fix Issue 19813 - Generated bt instruction seg faults, high 32 bits of register is garbage" was merged into master: - d80e14ba6037373f08c6dba274368408932d9e48 by Walter Bright: fix Issue 19813 optimization of bit test to OPbtst https://github.com/dlang/dmd/pull/9656