erik.pilkington created this revision.
erik.pilkington added reviewers: rsmith, manmanren.
erik.pilkington added a subscriber: cfe-commits.
The following valid code crashes Clang in CodeGen:
```
void other_test() {
switch(0) {
case 0:
do {
default:;
} while(0);
}
}
```
The problem is that when we constant fold the switch into the `case 0:` case,
the `default:` attempts to find the enclosing switch it is attached to, which
does not exist. The solution is to ignore the `default` and emit it's child
statement. (Which is the exact same solution as in the `case` statement, in
`EmitCaseStmt` just above this)
Fixes PR28609.
https://reviews.llvm.org/D22542
Files:
lib/CodeGen/CGStmt.cpp
test/CodeGenCXX/switch-case-folding-2.cpp
Index: test/CodeGenCXX/switch-case-folding-2.cpp
===================================================================
--- test/CodeGenCXX/switch-case-folding-2.cpp
+++ test/CodeGenCXX/switch-case-folding-2.cpp
@@ -18,4 +18,13 @@
return test(5);
}
+void other_test() {
+ switch(0) {
+ case 0:
+ do {
+ default:;
+ } while(0);
+ }
+}
+
// CHECK: call i32 (i8*, ...) @_Z6printfPKcz
Index: lib/CodeGen/CGStmt.cpp
===================================================================
--- lib/CodeGen/CGStmt.cpp
+++ lib/CodeGen/CGStmt.cpp
@@ -1261,6 +1261,14 @@
}
void CodeGenFunction::EmitDefaultStmt(const DefaultStmt &S) {
+ // If there is no enclosing switch instance that we're aware of, then this
+ // default statement can be elided. This situation only happens when we've
+ // constant-folded the switch.
+ if (!SwitchInsn) {
+ EmitStmt(S.getSubStmt());
+ return;
+ }
+
llvm::BasicBlock *DefaultBlock = SwitchInsn->getDefaultDest();
assert(DefaultBlock->empty() &&
"EmitDefaultStmt: Default block already defined?");
Index: test/CodeGenCXX/switch-case-folding-2.cpp
===================================================================
--- test/CodeGenCXX/switch-case-folding-2.cpp
+++ test/CodeGenCXX/switch-case-folding-2.cpp
@@ -18,4 +18,13 @@
return test(5);
}
+void other_test() {
+ switch(0) {
+ case 0:
+ do {
+ default:;
+ } while(0);
+ }
+}
+
// CHECK: call i32 (i8*, ...) @_Z6printfPKcz
Index: lib/CodeGen/CGStmt.cpp
===================================================================
--- lib/CodeGen/CGStmt.cpp
+++ lib/CodeGen/CGStmt.cpp
@@ -1261,6 +1261,14 @@
}
void CodeGenFunction::EmitDefaultStmt(const DefaultStmt &S) {
+ // If there is no enclosing switch instance that we're aware of, then this
+ // default statement can be elided. This situation only happens when we've
+ // constant-folded the switch.
+ if (!SwitchInsn) {
+ EmitStmt(S.getSubStmt());
+ return;
+ }
+
llvm::BasicBlock *DefaultBlock = SwitchInsn->getDefaultDest();
assert(DefaultBlock->empty() &&
"EmitDefaultStmt: Default block already defined?");
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