Detect early JIT compilation issues in CI/CD

This commit introduces a comprehensive JIT debugging infrastructure to
catch register allocation conflicts and cache coherency issues before
they cause subtle runtime failures in production.

Author: jserv

.ci/jit-debug-test.sh

@@ -0,0 +1,54 @@
+#!/usr/bin/env bash
+
+# JIT Debug Test Script
+# This script tests JIT compiler with debug mode enabled to catch issues early
+
+set -e
+
+PARALLEL="${PARALLEL:--j$(nproc 2>/dev/null || sysctl -n hw.ncpu 2>/dev/null || echo 4)}"
+
+echo "======================================"
+echo "JIT Debug Mode Test"
+echo "======================================"
+
+# Test 1: Standard JIT with debug
+echo ""
+echo "Test 1: Building with ENABLE_JIT_DEBUG=1..."
+make distclean
+make ENABLE_JIT=1 ENABLE_JIT_DEBUG=1 $PARALLEL
+
+echo ""
+echo "Running basic tests with JIT debug..."
+make ENABLE_JIT=1 ENABLE_JIT_DEBUG=1 check
+
+# Test 2: JIT with EXT_C=0 and debug (regression test)
+echo ""
+echo "Test 2: Building with ENABLE_EXT_C=0 ENABLE_JIT_DEBUG=1..."
+make distclean
+make ENABLE_EXT_C=0 ENABLE_JIT=1 ENABLE_JIT_DEBUG=1 $PARALLEL
+
+echo ""
+echo "Running tests with EXT_C=0 and JIT debug..."
+make ENABLE_EXT_C=0 ENABLE_JIT=1 ENABLE_JIT_DEBUG=1 check
+
+# Test 3: JIT with various extension combinations
+echo ""
+echo "Test 3: Testing multiple JIT configurations with debug..."
+for config in \
+    "ENABLE_EXT_A=0" \
+    "ENABLE_EXT_F=0" \
+    "ENABLE_EXT_M=0" \
+    "ENABLE_Zba=0" \
+    "ENABLE_Zbb=0"
+do
+    echo ""
+    echo "Testing: $config with JIT debug"
+    make distclean
+    make $config ENABLE_JIT=1 ENABLE_JIT_DEBUG=1 $PARALLEL
+    make $config ENABLE_JIT=1 ENABLE_JIT_DEBUG=1 check
+done
+
+echo ""
+echo "======================================"
+echo "All JIT debug tests passed!"
+echo "======================================"

.github/workflows/main.yml

@@ -461,6 +461,14 @@ jobs:
              make ENABLE_JIT=1 clean && make ENABLE_MOP_FUSION=0 ENABLE_JIT=1 check $PARALLEL
              make ENABLE_JIT=1 clean && make ENABLE_BLOCK_CHAINING=0 ENABLE_JIT=1 check $PARALLEL
        if: ${{ always() }}
+     - name: JIT debug test
+       env:
+         CC: ${{ steps.install_cc.outputs.cc }}
+       run: |
+             # Run JIT tests with debug mode to catch register allocation and cache coherency issues
+             make distclean && make ENABLE_JIT=1 ENABLE_JIT_DEBUG=1 check $PARALLEL
+             make distclean && make ENABLE_EXT_C=0 ENABLE_JIT=1 ENABLE_JIT_DEBUG=1 check $PARALLEL
+       if: ${{ always() }}
      - name: undefined behavior test
        env:
          CC: ${{ steps.install_cc.outputs.cc }}

Makefile

@@ -253,6 +253,11 @@ ENABLE_JIT ?= 0
 $(call set-feature, JIT)
 ifeq ($(call has, JIT), 1)
     OBJS_EXT += jit.o
+    # JIT debug mode for early issue detection in CI/CD
+    ENABLE_JIT_DEBUG ?= 0
+    ifeq ("$(ENABLE_JIT_DEBUG)", "1")
+        CFLAGS += -DENABLE_JIT_DEBUG=1
+    endif
     ENABLE_T2C ?= 1
     $(call set-feature, T2C)
     ifeq ($(call has, T2C), 1)

src/jit.c

@@ -299,6 +299,79 @@ static inline void offset_map_insert(struct jit_state *state, block_t *block)
     __builtin___clear_cache((char *) (addr), (char *) (addr) + (size));
 #endif
 
+/* JIT debug helpers - enable with ENABLE_JIT_DEBUG=1 to detect issues early */
+#ifndef ENABLE_JIT_DEBUG
+#define ENABLE_JIT_DEBUG 0
+#endif
+
+#if ENABLE_JIT_DEBUG
+static void jit_dump_regmap(const char *ctx)
+{
+    rv_log_debug("JIT RegMap [%s]:", ctx);
+    for (int i = 0; i < n_host_regs; i++) {
+        if (register_map[i].vm_reg_idx >= 0) {
+            rv_log_debug("  Host R%d -> VM x%d (dirty=%d)",
+                        register_map[i].reg_idx,
+                        register_map[i].vm_reg_idx,
+                        register_map[i].dirty);
+        }
+    }
+}
+
+static void jit_check_regmap_conflict(int vm_reg, int host_reg, const char *insn)
+{
+    int found_idx = -1;
+    /* Check if VM register is already mapped */
+    for (int i = 0; i < n_host_regs; i++) {
+        if (register_map[i].vm_reg_idx == vm_reg) {
+            if (found_idx >= 0 && found_idx != i) {
+                /* VM register mapped to multiple host registers */
+                rv_log_error("JIT RegMap CONFLICT in %s: VM x%d mapped to "
+                            "Host R%d (idx %d) and R%d (idx %d)",
+                            insn, vm_reg,
+                            register_map[found_idx].reg_idx, found_idx,
+                            register_map[i].reg_idx, i);
+                jit_dump_regmap("CONFLICT");
+                assert(false);
+            }
+            found_idx = i;
+            /* Verify the found mapping is correct */
+            if (register_map[i].reg_idx != host_reg) {
+                rv_log_error("JIT RegMap CONFLICT in %s: VM x%d expected at "
+                            "Host R%d but found at R%d",
+                            insn, vm_reg, host_reg, register_map[i].reg_idx);
+                jit_dump_regmap("CONFLICT");
+                assert(false);
+            }
+        } else if (register_map[i].reg_idx == host_reg &&
+                   register_map[i].vm_reg_idx >= 0) {
+            /* Host register holds different VM register */
+            rv_log_error("JIT RegMap CONFLICT in %s: Host R%d already holds "
+                        "VM x%d, cannot map VM x%d",
+                        insn, host_reg, register_map[i].vm_reg_idx, vm_reg);
+            jit_dump_regmap("CONFLICT");
+            assert(false);
+        }
+    }
+}
+
+static void jit_verify_cache_coherency(struct jit_state *state, uint32_t pc) UNUSED;
+static void jit_verify_cache_coherency(struct jit_state *state, uint32_t pc)
+{
+    /* On ARM64, verify instruction cache was properly invalidated */
+#if defined(__aarch64__)
+    if (state->offset > 0) {
+        rv_log_debug("JIT: Cache coherency check at PC=0x%08x, offset=%u",
+                    pc, state->offset);
+    }
+#endif
+}
+#else
+#define jit_dump_regmap(ctx) do { } while (0)
+#define jit_check_regmap_conflict(vm_reg, host_reg, insn) do { } while (0)
+#define jit_verify_cache_coherency(state, pc) do { } while (0)
+#endif
+
 static bool should_flush = false;
 static void emit_bytes(struct jit_state *state, void *data, uint32_t len)
 {
@@ -1890,6 +1963,7 @@ static inline int map_vm_reg(struct jit_state *state, int vm_reg_idx)
     save_reg(state, idx);
     unmap_vm_reg(idx);
     set_vm_reg(idx, vm_reg_idx);
+    jit_check_regmap_conflict(vm_reg_idx, target_reg, "map_vm_reg");
     return target_reg;
 }
 
@@ -1933,6 +2007,14 @@ static inline int map_vm_reg_reserved(struct jit_state *state,
     save_reg(state, idx);
     unmap_vm_reg(idx);
     set_vm_reg(idx, vm_reg_idx);
+    jit_check_regmap_conflict(vm_reg_idx, target_reg, "map_vm_reg_reserved");
+    /* Additional check: ensure we didn't allocate the reserved register */
+    if (target_reg == reserved_reg_idx) {
+        rv_log_error("JIT RegMap ERROR: map_vm_reg_reserved allocated reserved "
+                    "register R%d for VM x%d",
+                    reserved_reg_idx, vm_reg_idx);
+        assert(false);
+    }
     return target_reg;
 }