hakorune/docs/development/current/main/phase220-condition-env-integration.md

Phase 220-B: ConditionEnv Integration for If-Sum

Overview

Integrated ConditionEnv infrastructure into if-sum lowerer to support variable conditions like loop(i < len).

Implementation Status

Completed

• ✅ ConditionEnv construction in lower_if_sum_pattern()
• ✅ extract_value_or_variable() function (supports both literals and variables)
• ✅ Updated extract_loop_condition() and extract_if_condition() to use ConditionEnv
• ✅ JoinIR generation includes condition-only variables as parameters
• ✅ Condition bindings wired to boundary builder
• ✅ Updated call sites in pattern3_with_if_phi.rs

In Progress

• 🔧 Issue: phase212_if_sum_min.hako returns RC=0 instead of RC=2
• 🔧 Root Cause: Condition variable (len) remapping issue during merge
  • HOST ValueId(6) → JoinIR ValueId(101) → After merge ValueId(10) ❌
  • Expected: HOST ValueId(6) → JoinIR ValueId(101) → After merge ValueId(6) ✅
• 🔧 Next Step: Investigate condition_bindings handling in merge pipeline

Implementation

Pattern 2 Reference

Followed proven Pattern 2 (break condition) integration pattern:

1. Build ConditionEnv early with extract_condition_variables
2. Pass to condition lowering functions
3. Lookup variables via cond_env.get()
4. Wire condition_bindings to JoinInlineBoundary

Key Changes

File: src/mir/join_ir/lowering/loop_with_if_phi_if_sum.rs

• Added ConditionEnv construction (lines 70-127)
• Updated signature to accept variable_map, loop_var_name, loop_var_id
• Return type changed to include Vec<ConditionBinding>
• JoinIR generation updated to include condition variables as parameters

File: src/mir/builder/control_flow/joinir/patterns/pattern3_with_if_phi.rs

• Updated call site to pass variable_map and loop context
• Wired condition_bindings to boundary builder (line 189)

ValueOrLiteral Enum

enum ValueOrLiteral {
    Literal(i64),
    Variable(String, ValueId),
}

Function Signatures Updated

fn extract_value_or_variable(
    node: &ASTNode,
    cond_env: &ConditionEnv,
) -> Result<ValueOrLiteral, String>

fn extract_loop_condition(
    cond: &ASTNode,
    cond_env: &ConditionEnv,
) -> Result<(String, CompareOp, ValueOrLiteral), String>

Test Results (Preliminary)

phase212_if_sum_min.hako

• Expected: RC=2
• Actual: RC=0 ❌
• Issue: Loop not executing (no print output)
• Debug: Condition variable len extracted correctly but remapping issue

Debug Trace

[joinir/pattern3/if-sum] Extracted 1 condition variables: ["len"]
[joinir/pattern3/if-sum] Condition variable 'len': host=ValueId(6), join=ValueId(101)
[if-sum/joinir] loop_step params: 4 total (3 carriers + 1 condition vars)
[DEBUG-177]   'len': JoinIR ValueId(101) → Some(ValueId(10))  ← Should be ValueId(6)

Design Principles

1. Reuse Existing Boxes (ConditionEnv/ConditionBinding)
2. Follow Pattern 2 Structure (proven blueprint)
3. Fail-Fast (variable not in ConditionEnv → error)
4. ParamRole::Condition Routing (separate from carriers)

Next Steps

1. Investigate Merge Pipeline:

   • Check how condition_bindings are processed in JoinIRConversionPipeline
   • Verify that condition variables are loaded at loop entry
   • Ensure remapping uses host_value from ConditionBinding

2. Add Load Instructions:

   • May need to generate Load instructions for condition variables at loop entry
   • Similar to how Pattern 2 handles break condition variables

3. Test Additional Cases:

   • phase218_json_if_sum_min.hako (expect RC=10)
   • Regression: loop_if_phi.hako (expect RC=2)
   • Regression: phase217_if_sum_multi_min.hako (expect RC=2)

Files Modified

Primary:

• src/mir/join_ir/lowering/loop_with_if_phi_if_sum.rs (ConditionEnv integration)
• src/mir/builder/control_flow/joinir/patterns/pattern3_with_if_phi.rs (call site update)

Documentation:

• docs/development/current/main/phase220-condition-env-integration.md (this file)

Important Notes

• Fail-Fast Maintained: Variables not in ConditionEnv cause explicit errors
• Method Call Limitation: defs.len() style not supported yet (Phase 221+)
• Pattern 2 Parity: Uses identical ConditionEnvBuilder API
• ParamRole Separation: Condition variables kept separate from carriers

Known Issues

1. Condition Variable Remapping (Critical):

   • Condition variables get remapped to wrong ValueIds during merge
   • Need to verify condition_bindings handling in merge pipeline

2. No Test Passing Yet:

   • phase212: RC=0 (expected 2) ❌
   • Other tests not yet verified

References

• Phase 171-fix: ConditionEnv
• Phase 200-A/B: ConditionBinding
• Phase 201: JoinValueSpace
• Pattern 2: Break Condition