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improved behavior on debug safety crash

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* instead of emitting a breakpoint for a debug safety crash,
   zig calls a panic function which prints an error message
   and a stack trace and then calls abort.
 * on freestanding OS, this panic function has a default
   implementation of a simple infinite loop.
 * users can override the panic implementation by providing
   `pub fn panic(message: []const u8) -> unreachable { }`
 * workaround for LLVM segfaulting when you try to use cold
   calling convention on ARM.

closes #245
This commit is contained in:
Andrew Kelley
2017-02-06 03:10:32 -05:00
parent 28f63b8a4f
commit 07a71fc322
10 changed files with 254 additions and 63 deletions
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84
src/codegen.cpp
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@@ -450,8 +450,56 @@ static bool ir_want_debug_safety(CodeGen *g, IrInstruction *instruction) {
return true;
}
static void gen_debug_safety_crash(CodeGen *g) {
LLVMBuildCall(g->builder, g->trap_fn_val, nullptr, 0, "");
static Buf *panic_msg_buf(PanicMsgId msg_id) {
switch (msg_id) {
case PanicMsgIdCount:
zig_unreachable();
case PanicMsgIdBoundsCheckFailure:
return buf_create_from_str("index out of bounds");
case PanicMsgIdCastNegativeToUnsigned:
return buf_create_from_str("attempt to cast negative value to unsigned integer");
case PanicMsgIdCastTruncatedData:
return buf_create_from_str("integer cast truncated bits");
case PanicMsgIdIntegerOverflow:
return buf_create_from_str("integer overflow");
case PanicMsgIdShiftOverflowedBits:
return buf_create_from_str("left shift overflowed bits");
case PanicMsgIdDivisionByZero:
return buf_create_from_str("division by zero");
case PanicMsgIdExactDivisionRemainder:
return buf_create_from_str("exact division produced remainder");
case PanicMsgIdSliceWidenRemainder:
return buf_create_from_str("slice widening size mismatch");
case PanicMsgIdUnwrapMaybeFail:
return buf_create_from_str("attempt to unwrap null");
case PanicMsgIdUnwrapErrFail:
return buf_create_from_str("attempt to unwrap error");
case PanicMsgIdUnreachable:
return buf_create_from_str("reached unreachable code");
}
zig_unreachable();
}
static LLVMValueRef get_panic_msg_ptr_val(CodeGen *g, PanicMsgId msg_id) {
ConstExprValue *val = &g->panic_msg_vals[msg_id];
if (val->llvm_global)
return val->llvm_global;
Buf *buf_msg = panic_msg_buf(msg_id);
ConstExprValue *array_val = create_const_str_lit(g, buf_msg);
init_const_slice(g, val, array_val, 0, buf_len(buf_msg), true);
render_const_val_global(g, val, "");
render_const_val(g, val);
assert(val->llvm_global);
return val->llvm_global;
}
static void gen_debug_safety_crash(CodeGen *g, PanicMsgId msg_id) {
LLVMValueRef fn_val = fn_llvm_value(g, g->panic_fn);
LLVMValueRef msg_arg = get_panic_msg_ptr_val(g, msg_id);
ZigLLVMBuildCall(g->builder, fn_val, &msg_arg, 1, g->panic_fn->type_entry->data.fn.calling_convention, "");
LLVMBuildUnreachable(g->builder);
}
@@ -477,7 +525,7 @@ static void add_bounds_check(CodeGen *g, LLVMValueRef target_val,
LLVMBuildCondBr(g->builder, lower_ok_val, lower_ok_block, bounds_check_fail_block);
LLVMPositionBuilderAtEnd(g->builder, bounds_check_fail_block);
gen_debug_safety_crash(g);
gen_debug_safety_crash(g, PanicMsgIdBoundsCheckFailure);
if (upper_value) {
LLVMPositionBuilderAtEnd(g->builder, lower_ok_block);
@@ -520,7 +568,7 @@ static LLVMValueRef gen_widen_or_shorten(CodeGen *g, bool want_debug_safety, Typ
LLVMBuildCondBr(g->builder, ok_bit, ok_block, fail_block);
LLVMPositionBuilderAtEnd(g->builder, fail_block);
gen_debug_safety_crash(g);
gen_debug_safety_crash(g, PanicMsgIdCastNegativeToUnsigned);
LLVMPositionBuilderAtEnd(g->builder, ok_block);
}
@@ -559,7 +607,7 @@ static LLVMValueRef gen_widen_or_shorten(CodeGen *g, bool want_debug_safety, Typ
LLVMBuildCondBr(g->builder, ok_bit, ok_block, fail_block);
LLVMPositionBuilderAtEnd(g->builder, fail_block);
gen_debug_safety_crash(g);
gen_debug_safety_crash(g, PanicMsgIdCastTruncatedData);
LLVMPositionBuilderAtEnd(g->builder, ok_block);
return trunc_val;
@@ -587,7 +635,7 @@ static LLVMValueRef gen_overflow_op(CodeGen *g, TypeTableEntry *type_entry, AddS
LLVMBuildCondBr(g->builder, overflow_bit, fail_block, ok_block);
LLVMPositionBuilderAtEnd(g->builder, fail_block);
gen_debug_safety_crash(g);
gen_debug_safety_crash(g, PanicMsgIdIntegerOverflow);
LLVMPositionBuilderAtEnd(g->builder, ok_block);
return result;
@@ -748,7 +796,7 @@ static LLVMValueRef gen_overflow_shl_op(CodeGen *g, TypeTableEntry *type_entry,
LLVMBuildCondBr(g->builder, ok_bit, ok_block, fail_block);
LLVMPositionBuilderAtEnd(g->builder, fail_block);
gen_debug_safety_crash(g);
gen_debug_safety_crash(g, PanicMsgIdShiftOverflowedBits);
LLVMPositionBuilderAtEnd(g->builder, ok_block);
return result;
@@ -773,7 +821,7 @@ static LLVMValueRef gen_div(CodeGen *g, bool want_debug_safety, LLVMValueRef val
LLVMBuildCondBr(g->builder, is_zero_bit, fail_block, ok_block);
LLVMPositionBuilderAtEnd(g->builder, fail_block);
gen_debug_safety_crash(g);
gen_debug_safety_crash(g, PanicMsgIdDivisionByZero);
LLVMPositionBuilderAtEnd(g->builder, ok_block);
}
@@ -801,7 +849,7 @@ static LLVMValueRef gen_div(CodeGen *g, bool want_debug_safety, LLVMValueRef val
LLVMBuildCondBr(g->builder, ok_bit, ok_block, fail_block);
LLVMPositionBuilderAtEnd(g->builder, fail_block);
gen_debug_safety_crash(g);
gen_debug_safety_crash(g, PanicMsgIdExactDivisionRemainder);
LLVMPositionBuilderAtEnd(g->builder, ok_block);
}
@@ -1038,7 +1086,7 @@ static LLVMValueRef ir_render_cast(CodeGen *g, IrExecutable *executable,
LLVMBuildCondBr(g->builder, ok_bit, ok_block, fail_block);
LLVMPositionBuilderAtEnd(g->builder, fail_block);
gen_debug_safety_crash(g);
gen_debug_safety_crash(g, PanicMsgIdSliceWidenRemainder);
LLVMPositionBuilderAtEnd(g->builder, ok_block);
}
@@ -1162,7 +1210,7 @@ static LLVMValueRef ir_render_unreachable(CodeGen *g, IrExecutable *executable,
IrInstructionUnreachable *unreachable_instruction)
{
if (ir_want_debug_safety(g, &unreachable_instruction->base) || g->is_test_build) {
gen_debug_safety_crash(g);
gen_debug_safety_crash(g, PanicMsgIdUnreachable);
} else {
LLVMBuildUnreachable(g->builder);
}
@@ -1622,7 +1670,7 @@ static LLVMValueRef ir_render_unwrap_maybe(CodeGen *g, IrExecutable *executable,
LLVMBuildCondBr(g->builder, non_null_bit, ok_block, fail_block);
LLVMPositionBuilderAtEnd(g->builder, fail_block);
gen_debug_safety_crash(g);
gen_debug_safety_crash(g, PanicMsgIdUnwrapMaybeFail);
LLVMPositionBuilderAtEnd(g->builder, ok_block);
}
@@ -2107,7 +2155,7 @@ static LLVMValueRef ir_render_unwrap_err_payload(CodeGen *g, IrExecutable *execu
LLVMBuildCondBr(g->builder, cond_val, ok_block, err_block);
LLVMPositionBuilderAtEnd(g->builder, err_block);
gen_debug_safety_crash(g);
gen_debug_safety_crash(g, PanicMsgIdUnwrapErrFail);
LLVMPositionBuilderAtEnd(g->builder, ok_block);
}
@@ -3849,6 +3897,12 @@ static PackageTableEntry *create_bootstrap_pkg(CodeGen *g) {
return package;
}
static PackageTableEntry *create_panic_pkg(CodeGen *g) {
PackageTableEntry *package = new_package(buf_ptr(g->zig_std_dir), "");
package->package_table.put(buf_create_from_str("std"), g->std_package);
return package;
}
void codegen_add_root_code(CodeGen *g, Buf *src_dir, Buf *src_basename, Buf *source_code) {
Buf source_path = BUF_INIT;
os_path_join(src_dir, src_basename, &source_path);
@@ -3873,6 +3927,10 @@ void codegen_add_root_code(CodeGen *g, Buf *src_dir, Buf *src_basename, Buf *sou
g->bootstrap_import = add_special_code(g, create_bootstrap_pkg(g), "bootstrap.zig");
}
}
if (!g->have_exported_panic) {
g->panic_package = create_panic_pkg(g);
add_special_code(g, g->panic_package, "panic.zig");
}
if (g->verbose) {
fprintf(stderr, "\nIR Generation and Semantic Analysis:\n");