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cpu/mips3: Fix DRC debugger interaction for register and memory modifications #14944

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cpu/mips3: Fix DRC debugger interaction for register and memory modifications #14944

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13 changes: 12 additions & 1 deletion src/devices/cpu/mips/mips3.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,8 @@

#include "emuopts.h"

#include "debug/express.h"

#include <cmath>

#define ENABLE_OVERFLOWS (0)
Expand Down Expand Up @@ -180,6 +182,7 @@ mips3_device::mips3_device(const machine_config &mconfig, device_type type, cons
, m_drcfe(nullptr)
, m_drcoptions(0)
, m_drc_cache_dirty(0)
, m_drc_iregs_dirty(0)
, m_entry(nullptr)
, m_nocode(nullptr)
, m_out_of_cycles(nullptr)
Expand Down Expand Up @@ -239,6 +242,14 @@ void mips3_device::device_stop()
}
}

void mips3_device::device_debug_setup()
{
if (!m_isdrc) return;
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@rb6502 rb6502 Feb 15, 2026

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This also should be Allman style.

debug()->symtable().set_memory_modified_func(
[this]() { m_drc_cache_dirty = true; }
);
Comment on lines +248 to +250
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@cuavas cuavas Feb 15, 2026

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You don't want to be doing this for every memory modification from the debugger - it's too expensive when most of the time, people will just be modifying data memory.

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@nekuz0r nekuz0r Feb 17, 2026 •
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The cache invalidation is triggered when editing the ':maincpu' program space, not through any other spaces/regions.
What is your suggestion ?

}

/***************************************************************************
EXECEPTION HANDLING
***************************************************************************/
Expand Down Expand Up @@ -826,7 +837,7 @@ void mips3_device::state_import(const device_state_entry &entry)
// this refers to HI as R32 and LO as R33 because I'm lazy
const unsigned regnum = entry.index() - MIPS3_R0;
if (m_regmap[regnum].is_int_register())
logerror("debugger R%u = %08X, must update UML I%u\n", regnum, m_core->r[regnum], m_regmap[regnum].ireg() - uml::REG_I0);
m_drc_iregs_dirty = true;
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@rb6502 rb6502 Feb 15, 2026

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The rest of this file uses Allman brace style, so this should too for consistency.

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@nekuz0r nekuz0r Feb 17, 2026 •
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There's quite a few one line if/else statements in the file without braces, i kept it as it, should i update it and update the other occurrences or leave it ?

}
}

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2 changes: 2 additions & 0 deletions src/devices/cpu/mips/mips3.h
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Expand Up @@ -320,6 +320,7 @@ class mips3_device : public cpu_device, public device_vtlb_interface {

protected:
// device_t implementation
virtual void device_debug_setup() override ATTR_COLD;
virtual void device_start() override ATTR_COLD;
virtual void device_reset() override ATTR_COLD;
virtual void device_stop() override ATTR_COLD;
Expand Down Expand Up @@ -486,6 +487,7 @@ class mips3_device : public cpu_device, public device_vtlb_interface {

/* internal stuff */
uint8_t m_drc_cache_dirty; /* true if we need to flush the cache */
uint32_t m_drc_iregs_dirty; /* true if debugger modified fast integer registers */

/* tables */
uint8_t m_fpmode[4]; /* FPU mode table */
Expand Down
9 changes: 8 additions & 1 deletion src/devices/cpu/mips/mips3drc.cpp
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Expand Up @@ -38,6 +38,7 @@
#define DEBUG_STRICT_VERIFY 0



/***************************************************************************
MACROS
***************************************************************************/
Expand Down Expand Up @@ -1366,9 +1367,15 @@ void mips3_device::generate_sequence_instruction(drcuml_block &block, compiler_s
/* if we are debugging, call the debugger */
if (debugger_enabled())
{
uml::code_label skip_reload = compiler.labelnum++;
UML_MOV(block, mem(&m_core->pc), desc->pc); // mov [pc],desc->pc
save_fast_iregs(block);
UML_DEBUG(block, desc->pc); // debug desc->pc
UML_DEBUG(block, desc->pc); // debug desc->pc
UML_TEST(block, mem(&m_drc_iregs_dirty), 1); // test [debugger_iregs_dirty],1
UML_JMPc(block, COND_Z, skip_reload); // jmp skip_reload,Z
UML_MOV(block, mem(&m_drc_iregs_dirty), 0); // mov [debugger_iregs_dirty],0
load_fast_iregs(block); // <load fast integer registers>
UML_LABEL(block, skip_reload); // skip_reload:
Comment on lines -1371 to +1378
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@cuavas cuavas Feb 15, 2026

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Considering how frequently this is going to occur, would it be better to turn it into a helper function to keep generated code size down?

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@nekuz0r nekuz0r Feb 17, 2026

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Not sure to understand what's expected to be done, any guidance ?

}

/* if we hit an unmapped address, fatal error */
Expand Down