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FLDLG2

Loads the 64-bit floating-point constant (the base-2 logarithm of 2) onto the ST(0) register of the x87 FPU stack.

The table after the description covers what the source and destinations can be.

DO NOT support LOCK

This instruction is available in 64-bit mode, 32-bit mode, and compatibility mode. It does not require a source operand as the value is an implicit architectural constant.

The instruction increments the FPU stack pointer (TOP). If the stack pointer is already at the maximum value (4), a stack overflow exception (#SS) SHALL occur. The precision of the loaded constant depends on the current FPU control word setting.