Initial support for Win64 SEH IR emission
The lowering looks a lot like normal EH lowering, with the exception
that the exceptions are caught by executing filter expression code
instead of matching typeinfo globals. The filter expressions are
outlined into functions which are used in landingpad clauses where
typeinfo would normally go.
Major aspects that still need work:
- Non-call exceptions in __try bodies won't work yet. The plan is to
outline the __try block in the frontend to keep things simple.
- Filter expressions cannot use local variables until capturing is
implemented.
- __finally blocks will not run after exceptions. Fixing this requires
work in the LLVM SEH preparation pass.
The IR lowering looks like this:
// C code:
bool safe_div(int n, int d, int *r) {
__try {
*r = normal_div(n, d);
} __except(_exception_code() == EXCEPTION_INT_DIVIDE_BY_ZERO) {
return false;
}
return true;
}
; LLVM IR:
define i32 @filter(i8* %e, i8* %fp) {
%ehptrs = bitcast i8* %e to i32**
%ehrec = load i32** %ehptrs
%code = load i32* %ehrec
%matches = icmp eq i32 %code, i32 u0xC0000094
%matches.i32 = zext i1 %matches to i32
ret i32 %matches.i32
}
define i1 zeroext @safe_div(i32 %n, i32 %d, i32* %r) {
%rr = invoke i32 @normal_div(i32 %n, i32 %d)
to label %normal unwind to label %lpad
normal:
store i32 %rr, i32* %r
ret i1 1
lpad:
%ehvals = landingpad {i8*, i32} personality i32 (...)* @__C_specific_handler
catch i8* bitcast (i32 (i8*, i8*)* @filter to i8*)
%ehptr = extractvalue {i8*, i32} %ehvals, i32 0
%sel = extractvalue {i8*, i32} %ehvals, i32 1
%filter_sel = call i32 @llvm.eh.seh.typeid.for(i8* bitcast (i32 (i8*, i8*)* @filter to i8*))
%matches = icmp eq i32 %sel, %filter_sel
br i1 %matches, label %eh.except, label %eh.resume
eh.except:
ret i1 false
eh.resume:
resume
}
Reviewers: rjmccall, rsmith, majnemer
Differential Revision: http://reviews.llvm.org/D5607
llvm-svn: 226760
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index a070944..c28325a 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -202,6 +202,28 @@
return false;
}
+static bool SemaBuiltinSEHScopeCheck(Sema &SemaRef, CallExpr *TheCall,
+ Scope::ScopeFlags NeededScopeFlags,
+ unsigned DiagID) {
+ // Scopes aren't available during instantiation. Fortunately, builtin
+ // functions cannot be template args so they cannot be formed through template
+ // instantiation. Therefore checking once during the parse is sufficient.
+ if (!SemaRef.ActiveTemplateInstantiations.empty())
+ return false;
+
+ Scope *S = SemaRef.getCurScope();
+ while (S && !S->isSEHExceptScope())
+ S = S->getParent();
+ if (!S || !(S->getFlags() & NeededScopeFlags)) {
+ auto *DRE = cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
+ SemaRef.Diag(TheCall->getExprLoc(), DiagID)
+ << DRE->getDecl()->getIdentifier();
+ return true;
+ }
+
+ return false;
+}
+
ExprResult
Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
CallExpr *TheCall) {
@@ -461,6 +483,22 @@
if (SemaBuiltinCallWithStaticChain(*this, TheCall))
return ExprError();
break;
+
+ case Builtin::BI__exception_code:
+ case Builtin::BI_exception_code: {
+ if (SemaBuiltinSEHScopeCheck(*this, TheCall, Scope::SEHExceptScope,
+ diag::err_seh___except_block))
+ return ExprError();
+ break;
+ }
+ case Builtin::BI__exception_info:
+ case Builtin::BI_exception_info: {
+ if (SemaBuiltinSEHScopeCheck(*this, TheCall, Scope::SEHFilterScope,
+ diag::err_seh___except_filter))
+ return ExprError();
+ break;
+ }
+
}
// Since the target specific builtins for each arch overlap, only check those