1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
|
// slang-ir-lower-error-handling.cpp
#include "slang-ir-lower-error-handling.h"
#include "slang-ir.h"
#include "slang-ir-insts.h"
namespace Slang
{
struct ErrorHandlingLoweringContext
{
IRModule* module;
DiagnosticSink* diagnosticSink;
List<IRInst*> workList;
HashSet<IRInst*> workListSet;
void addToWorkList(IRInst* inst)
{
if (workListSet.Contains(inst))
return;
workList.add(inst);
workListSet.Add(inst);
}
void processFuncType(IRFuncType* funcType)
{
auto throwAttr = funcType->findAttr<IRFuncThrowTypeAttr>();
if (!throwAttr)
return;
IRBuilder builder(module);
builder.setInsertBefore(funcType);
auto resultType =
builder.getResultType(funcType->getResultType(), throwAttr->getErrorType());
List<IRType*> paramTypes;
for (UInt i = 0; i < funcType->getParamCount(); i++)
{
if (as<IRAttr>(funcType->getParamType(i)))
break;
paramTypes.add(funcType->getParamType(i));
}
auto newFuncType = builder.getFuncType(paramTypes, resultType);
funcType->replaceUsesWith(newFuncType);
}
void processTryCall(IRTryCall* tryCall)
{
// If we see:
// ```
// value = tryCall(callee, successBlock, failBlock, args)
// successBlock:
// resultParam = IRParam<resultType>
// ... (uses resultParam) ...
// failBlock:
// errorParam = IRParam<errorType>
// (uses errorParam)
// ```
// We need to rewrite it as
// ```
// result = call(callee) : Result<callee.returnType, callee.errorType>
// isError = isResultError(result)
// ifElse(isError, failBlock, successBlock)
// successBlock:
// value = getResultValue(result) : returnType
// ... (replaces resultParam with value)
// failBlock:
// error = getResultError(result) : errorType
// ... (replaces errorParam with error)
// ```
IRFuncType* funcType = cast<IRFuncType>(tryCall->getCallee()->getDataType());
auto resultValueType = funcType->getResultType();
auto throwAttr = funcType->findAttr<IRFuncThrowTypeAttr>();
if (!throwAttr)
{
SLANG_ASSERT_FAILURE("tryCall applied to callee without a IRFuncThrowTypeAttr");
}
auto errorType = throwAttr->getErrorType();
IRBuilder builder(module);
builder.setInsertBefore(tryCall);
auto resultType = builder.getResultType(resultValueType, errorType);
List<IRInst*> args;
for (UInt i = 0; i < tryCall->getArgCount(); i++)
{
args.add(tryCall->getArg(i));
}
auto call = builder.emitCallInst(resultType, tryCall->getCallee(), args);
tryCall->transferDecorationsTo(call);
auto isFail = builder.emitIsResultError(call);
auto failBlock = tryCall->getFailureBlock();
auto successBlock = tryCall->getSuccessBlock();
builder.emitIf(isFail, failBlock, successBlock);
// Replace the params in failBlock to `getResultError(call)`.
builder.setInsertBefore(failBlock->getFirstOrdinaryInst());
auto errorParam = failBlock->getFirstParam();
auto errVal = builder.emitGetResultError(call);
errorParam->replaceUsesWith(errVal);
errorParam->removeAndDeallocate();
// Replace the params in successBlock to `getResultValue(call)`.
builder.setInsertBefore(successBlock->getFirstOrdinaryInst());
auto resultParam = successBlock->getFirstParam();
auto resultValue = builder.emitGetResultValue(call);
resultParam->replaceUsesWith(resultValue);
resultParam->removeAndDeallocate();
tryCall->removeAndDeallocate();
}
void processReturn(IRReturn* ret)
{
auto parentFunc = getParentFunc(ret);
if (!parentFunc)
return;
auto funcType = cast<IRFuncType>(parentFunc->getDataType());
auto throwAttr = funcType->findAttr<IRFuncThrowTypeAttr>();
if (!throwAttr)
return;
// If we are in a throwing function and sees a `return(val)` inst,
// replace it with a `return makeResultValue(val)`, so that it returns a `Result<T,E>` type.
IRBuilder builder(module);
builder.setInsertBefore(ret);
auto resultType =
builder.getResultType(funcType->getResultType(), throwAttr->getErrorType());
IRInst* resultVal = nullptr;
auto val = cast<IRReturn>(ret)->getVal();
resultVal = builder.emitMakeResultValue(resultType, val);
builder.emitReturn(resultVal);
ret->removeAndDeallocate();
}
void processThrow(IRThrow* throwInst)
{
auto parentFunc = getParentFunc(throwInst);
SLANG_ASSERT(parentFunc);
auto funcType = cast<IRFuncType>(parentFunc->getDataType());
auto throwAttr = funcType->findAttr<IRFuncThrowTypeAttr>();
SLANG_ASSERT(throwAttr);
// If we are in a throwing function and sees a `throw(e)` inst,
// replace it with a `return makeResultError(e)`.
IRBuilder builder(module);
builder.setInsertBefore(throwInst);
auto resultType =
builder.getResultType(funcType->getResultType(), throwAttr->getErrorType());
IRInst* resultVal = builder.emitMakeResultError(resultType, throwInst->getValue());
builder.emitReturn(resultVal);
throwInst->removeAndDeallocate();
}
void processInst(IRInst* inst)
{
switch (inst->getOp())
{
case kIROp_TryCall:
processTryCall(cast<IRTryCall>(inst));
break;
case kIROp_Return:
processReturn(cast<IRReturn>(inst));
break;
case kIROp_Throw:
processThrow(cast<IRThrow>(inst));
break;
default:
break;
}
}
void processInsts()
{
addToWorkList(module->getModuleInst());
while (workList.getCount() != 0)
{
IRInst* inst = workList.getLast();
workList.removeLast();
workListSet.Remove(inst);
processInst(inst);
for (auto child = inst->getLastChild(); child; child = child->getPrevInst())
{
addToWorkList(child);
}
}
}
void processModule()
{
// Translate all IRTryCall, IRThrow, IRReturn.
processInsts();
// Lower all functypes.
// Function types with an IRThrowTypeAttribute will be translated into a normal function
// type that returns `Result<T,E>`.
List<IRFuncType*> oldFuncTypes;
for (auto child : module->getGlobalInsts())
{
switch (child->getOp())
{
case kIROp_FuncType:
oldFuncTypes.add(cast<IRFuncType>(child));
break;
default:
break;
}
}
for (auto funcType : oldFuncTypes)
{
processFuncType(funcType);
}
}
};
void lowerErrorHandling(IRModule* module, DiagnosticSink* sink)
{
ErrorHandlingLoweringContext context;
context.module = module;
context.diagnosticSink = sink;
return context.processModule();
}
}
|
