A float parameter of a stackless generator arrives as its bit pattern

function G(d: Double): Double; generator; stackless;
begin
  WriteLn(d:0:2);   // 4612811918334230528.00
  yield d;          // the loop variable got the bit pattern
end;

Mechanism

A generator instance slot is one Int64 word, written with SlSet(g, off, v: Int64) and read with SlGet. A Double stored that way is converted to an integer on the way in and back on the way out. The caller stored arguments that way, the step saved and restored locals that way, and the yield published the element that way.

Fix

In pasparser_stmt.inc, float slots are copied bitwise at their own width (SLFloatSlotBytes: 4 for Single, 8 otherwise):

• GenSeedArg seeds a float argument through a temp of the parameter's kind, then SlBlob. The temp also converts an integer argument, as a plain call would.
• SLSaveLocals and SLRestoreLocals use SlBlob and SlUnblob.
• SLLowerYield blobs a float element into the CURRENT word, and the for consumer unblobs it into a temp of the element kind, then assigns.
• Nil Python's PyBuildGeneratorValue seeds through GenSeedArg.

Test

test/test_stackless_float_param_and_element.pas: a row in test-core and rows in test-i386, test-aarch64 and test-arm32. riscv32 was also measured. Measured wrong with pin v446 (stable_linux_amd64/default/stable_pinned) on 2026-09-28.