Fix PR13910: Don't warn that __builtin_unreachable() is unreachable
Differential Revision: https://reviews.llvm.org/D25321
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@299951 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit eaaf906b8552a690efecd1a5cf5ebb8772e82504)
diff --git a/lib/Analysis/ReachableCode.cpp b/lib/Analysis/ReachableCode.cpp
index 8a96744..60724ea 100644
--- a/lib/Analysis/ReachableCode.cpp
+++ b/lib/Analysis/ReachableCode.cpp
@@ -58,6 +58,14 @@
return false;
}
+static bool isBuiltinUnreachable(const Stmt *S) {
+ if (const auto *DRE = dyn_cast<DeclRefExpr>(S))
+ if (const auto *FDecl = dyn_cast<FunctionDecl>(DRE->getDecl()))
+ return FDecl->getIdentifier() &&
+ FDecl->getBuiltinID() == Builtin::BI__builtin_unreachable;
+ return false;
+}
+
static bool isDeadReturn(const CFGBlock *B, const Stmt *S) {
// Look to see if the current control flow ends with a 'return', and see if
// 'S' is a substatement. The 'return' may not be the last element in the
@@ -592,8 +600,7 @@
if (isa<BreakStmt>(S)) {
UK = reachable_code::UK_Break;
- }
- else if (isTrivialDoWhile(B, S)) {
+ } else if (isTrivialDoWhile(B, S) || isBuiltinUnreachable(S)) {
return;
}
else if (isDeadReturn(B, S)) {
diff --git a/test/Sema/warn-unreachable.c b/test/Sema/warn-unreachable.c
index 1f79216..440aa0a 100644
--- a/test/Sema/warn-unreachable.c
+++ b/test/Sema/warn-unreachable.c
@@ -461,3 +461,40 @@
if (!true) // expected-note {{silence by adding parentheses to mark code as explicitly dead}}
testTrueFalseMacros(); // expected-warning {{code will never be executed}}
}
+
+int pr13910_foo(int x) {
+ if (x == 1)
+ return 0;
+ else
+ return x;
+ __builtin_unreachable(); // expected no warning
+}
+
+int pr13910_bar(int x) {
+ switch (x) {
+ default:
+ return x + 1;
+ }
+ pr13910_foo(x); // expected-warning {{code will never be executed}}
+}
+
+int pr13910_bar2(int x) {
+ if (x == 1)
+ return 0;
+ else
+ return x;
+ pr13910_foo(x); // expected-warning {{code will never be executed}}
+ __builtin_unreachable(); // expected no warning
+ pr13910_foo(x); // expected-warning {{code will never be executed}}
+}
+
+void pr13910_noreturn() {
+ raze();
+ __builtin_unreachable(); // expected no warning
+}
+
+void pr13910_assert() {
+ myassert(0 && "unreachable");
+ return;
+ __builtin_unreachable(); // expected no warning
+}
