Make skipping of vardecls more precise: it's ok to skip a decl if the entire
compound stmt containing the decl is skipped.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@126639 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGStmt.cpp b/lib/CodeGen/CGStmt.cpp
index 21fb36a..24acf65 100644
--- a/lib/CodeGen/CGStmt.cpp
+++ b/lib/CodeGen/CGStmt.cpp
@@ -887,9 +887,16 @@
// the skipped statements must be skippable) or we might already have it.
CompoundStmt::const_body_iterator I = CS->body_begin(), E = CS->body_end();
if (Case) {
+ // Keep track of whether we see a skipped declaration. The code could be
+ // using the declaration even if it is skipped, so we can't optimize out
+ // the decl if the kept statements might refer to it.
+ bool HadSkippedDecl = false;
+
// If we're looking for the case, just see if we can skip each of the
// substatements.
for (; Case && I != E; ++I) {
+ HadSkippedDecl |= isa<DeclStmt>(I);
+
switch (CollectStatementsForCase(*I, Case, FoundCase, ResultStmts)) {
case CSFC_Failure: return CSFC_Failure;
case CSFC_Success:
@@ -898,6 +905,11 @@
// and also contains the break to exit the switch. In the later case,
// we just verify the rest of the statements are elidable.
if (FoundCase) {
+ // If we found the case and skipped declarations, we can't do the
+ // optimization.
+ if (HadSkippedDecl)
+ return CSFC_Failure;
+
for (++I; I != E; ++I)
if (CodeGenFunction::ContainsLabel(*I, true))
return CSFC_Failure;
@@ -911,6 +923,11 @@
assert(FoundCase && "Didn't find case but returned fallthrough?");
// We recursively found Case, so we're not looking for it anymore.
Case = 0;
+
+ // If we found the case and skipped declarations, we can't do the
+ // optimization.
+ if (HadSkippedDecl)
+ return CSFC_Failure;
break;
}
}
@@ -943,9 +960,7 @@
// for statement or increment etc. If we are skipping over this statement,
// just verify it doesn't have labels, which would make it invalid to elide.
if (Case) {
- if (CodeGenFunction::ContainsLabel(S, true) ||
- // Don't skip over DeclStmts, which can be used even if skipped over.
- isa<DeclStmt>(S))
+ if (CodeGenFunction::ContainsLabel(S, true))
return CSFC_Failure;
return CSFC_Success;
}