TCE

tcedisasm prints unsigned immediates incorrectly

Bug #1250451 reported by Heikki Kultala
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
TCE
Fix Committed
Low
Jesper Hjorth

Bug Description

Bus has for example 8-bit unsigned short immediate (values 0..255).

Values 255 is being transferred via the bus.
tcedisasm shows the immediate value as -1 instead of 255, it always interprets them as signed.

Revision history for this message
Heikki Kultala (hkultala) wrote :

It seems sometimes also -1 gets printed as UINT_MAX

Jesper Hjorth (jesper-hjorth)
Changed in tce:
assignee: nobody → Jesper Hjorth (jesper-hjorth)
status: New → In Progress
Jesper Hjorth (jesper-hjorth)
Changed in tce:
status: In Progress → Fix Committed
Revision history for this message
Jesper Hjorth (jesper-hjorth) wrote :

Ended up fixing the code to be similar to the one used in dumptpef since it seems to work:

TPEFProgramFactory.cc
784 if (imm->isInline()) {
785
786 // should use bus width, but universal machine messes this up
787 // (since it has 64 busses)
788 SimValue simValue(32);
789 simValue = imm->word();

the bug should fix also by using the bus width, but then universal machine breaks the tests. Probably some bugs in simvalue are also responsible (e.g. when using SimValue operator= the bit width is not always reassigned, but it's clear whether or not this is intentional)

Revision history for this message
Pekka Jääskeläinen (pekka-jaaskelainen) wrote :

This needs more attention. Where does the magic 32 number come from? If you suspect a bug elsewhere, it should be fixed elsewhere not trying to workaround it somewhere else with a potentially new issue. Why is UM a problem, can you explain a bit more?

It should not be the bus width, but the short immediate slot width of the bus (move slot in the instruction) in question, as far as I understood from a quick look.

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