short circuit && and || when possible. This substantially reduces
the size of the -O0 output on some cases. For example, on expr.c from
176.gcc, it shrinks the .ll file from 43164 to 42835 lines, and removed
references to two external symbols.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@59034 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CodeGenFunction.cpp b/lib/CodeGen/CodeGenFunction.cpp
index 427f645..1a26610 100644
--- a/lib/CodeGen/CodeGenFunction.cpp
+++ b/lib/CodeGen/CodeGenFunction.cpp
@@ -163,6 +163,36 @@
return false;
}
+/// ContainsLabel - Return true if the statement contains a label in it. If
+/// this statement is not executed normally, it not containing a label means
+/// that we can just remove the code.
+bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) {
+ // Null statement, not a label!
+ if (S == 0) return false;
+
+ // If this is a label, we have to emit the code, consider something like:
+ // if (0) { ... foo: bar(); } goto foo;
+ if (isa<LabelStmt>(S))
+ return true;
+
+ // If this is a case/default statement, and we haven't seen a switch, we have
+ // to emit the code.
+ if (isa<SwitchCase>(S) && !IgnoreCaseStmts)
+ return true;
+
+ // If this is a switch statement, we want to ignore cases below it.
+ if (isa<SwitchStmt>(S))
+ IgnoreCaseStmts = true;
+
+ // Scan subexpressions for verboten labels.
+ for (Stmt::const_child_iterator I = S->child_begin(), E = S->child_end();
+ I != E; ++I)
+ if (ContainsLabel(*I, IgnoreCaseStmts))
+ return true;
+
+ return false;
+}
+
/// getCGRecordLayout - Return record layout info.
const CGRecordLayout *CodeGenFunction::getCGRecordLayout(CodeGenTypes &CGT,
QualType Ty) {