fix rdar://6586493, a bug in codegen of the GNU
missing-?:-true-value extension.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@64505 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGExprScalar.cpp b/lib/CodeGen/CGExprScalar.cpp
index 962c2eb..164d57e 100644
--- a/lib/CodeGen/CGExprScalar.cpp
+++ b/lib/CodeGen/CGExprScalar.cpp
@@ -1270,20 +1270,30 @@
llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
Value *CondVal = 0;
- // If we have the GNU missing condition extension, evaluate the conditional
- // and then convert it to bool the hard way. We do this explicitly
- // because we need the unconverted value for the missing middle value of
- // the ?:.
- if (E->getLHS() == 0) {
+ // If we don't have the GNU missing condition extension, emit a branch on
+ // bool the normal way.
+ if (E->getLHS()) {
+ // Otherwise, just use EmitBranchOnBoolExpr to get small and simple code for
+ // the branch on bool.
+ CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock);
+ } else {
+ // Otherwise, for the ?: extension, evaluate the conditional and then
+ // convert it to bool the hard way. We do this explicitly because we need
+ // the unconverted value for the missing middle value of the ?:.
CondVal = CGF.EmitScalarExpr(E->getCond());
+
+ // In some cases, EmitScalarConversion will delete the "CondVal" expression
+ // if there are no extra uses (an optimization). Inhibit this by making an
+ // extra dead use, because we're going to add a use of CondVal later. We
+ // don't use the builder for this, because we don't want it to get optimized
+ // away. This leaves dead code, but the ?: extension isn't common.
+ new llvm::BitCastInst(CondVal, CondVal->getType(), "dummy?:holder",
+ Builder.GetInsertBlock());
+
Value *CondBoolVal =
CGF.EmitScalarConversion(CondVal, E->getCond()->getType(),
CGF.getContext().BoolTy);
Builder.CreateCondBr(CondBoolVal, LHSBlock, RHSBlock);
- } else {
- // Otherwise, just use EmitBranchOnBoolExpr to get small and simple code for
- // the branch on bool.
- CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock);
}
CGF.EmitBlock(LHSBlock);